HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Erratum (v24,p418) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hunter, T. B. Articles by Berger, W. G. Search for Related Content PubMed PubMed Citation Articles by Hunter, T. B. Articles by Berger, W. G. Related Collections Musculoskeletal Radiology Neuroradiology

Medical Devices of the Head, Neck, and Spine¹

¹ From the Departments of Radiology (T.B.H., W.G.B.) and Orthopaedic Surgery (R.B.D.), University of Arizona College of Medicine, 1501 N Campbell Ave, PO Box 245067, Tucson, AZ 85724-5067; Arizona State Radiology, Tucson, Ariz (M.T.Y.); and Rick Light, DDS, Tucson, Ariz (R.A.L.). Received August 22, 2003; revision requested September 2 and received October 13; accepted October 13. Address correspondence to T.B.H. (e-mail: tbh@3towers.com).

	Abstract

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

 
There are many medical devices used for head, neck, and spinal diseases and injuries, and new devices are constantly being introduced. Many of the newest devices are variations on a previous theme. Knowing the specific name of a device is not important. It is important to recognize the presence of a device and to have an understanding of its function as well as to be able to recognize the complications associated with its use. The article discusses the most common and important devices of the head, neck, and spine, including cerebrospinal fluid shunts and the Codman Hakim programmable valve; subdural drainage catheters, subdural electrodes, intracranial electrodes, deep brain stimulators, and cerebellar electrodes; coils, balloons, adhesives, particles, and aneurysm clips; radiation therapy catheters, intracranial balloons for drug installation, and carmustine wafers; hearing aids, cochlear implants, and ossicular reconstruction prostheses; orbital prostheses, intraocular silicone oil, and lacrimal duct stents; anterior and posterior cervical plates, posterior cervical spine wiring, odontoid fracture fixation devices, cervical collars and halo vests; thoracic and lumbar spine implants, anterior and posterior instrumentation for the thoracic and lumbar spine, vertebroplasty, and artificial disks; spinal column stimulators, bone stimulators, intrathecal drug delivery pumps, and sacral stimulators; dental and facial implant devices; gastric and tracheal tubes; vagus nerve stimulators; lumboperitoneal shunts; and temperature- and oxygen-sensing probes.

© RSNA, 2004

Index Terms: Bones, grafts, 30.46 • Catheters and catheterization, 20.46, 30.46 • Feeding tubes, 30.46 • Radiations, protective and therapeutic agents and devices, 20.46, 30.46 • Spine, fixation devices, 30.46 • Stents and prostheses, 20.46, 30.46

	Introduction

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

 
Many medical devices are used in the treatment of head, neck, and spinal diseases and injuries, and new devices are constantly being introduced. Most devices found in everyday practice, however, have been used for a number of years. Many of the newest devices are variations on a previous theme. Knowing the specific name of a device is not important; in fact, it is sometimes impossible, because a slight modification of a device design usually leads to a new name. It is important, however, to recognize the presence or absence of a device (if the patient’s clinical history suggests one is present), to understand its function, and to identify the complications associated with its use. The referring physician knows what device he or she has installed, but he or she relies on the radiologist to determine the postoperative location of the device and its integrity. The article discusses the most common and important devices of the head, neck, and spine.

	Brain and Skull

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

 
Cerebrospinal Fluid Shunts and the Codman Hakim Programmable Valve
Cerebrospinal fluid (CSF) drainage procedures to relieve elevated CSF pressure have been performed for at least 100 years. The commonly used drainage procedures drain excess fluid either to the peritoneum or, sometimes, to the right atrium. The present shunts are used to drain CSF past areas of intracerebral obstruction and to decrease CSF pressure (1–3). Each works through the use of associated pressure valves and antisiphon devices. In practice, any location within the lateral ventricle is an acceptable position for the shunt, although the ideal location is near the foramen of Monro. The most common shunts are ventriculoperitoneal. On plain radiographs, they are not well visualized, being composed mainly of relatively radiolucent materials, although they may have metallic tips and connectors (Fig 1). Adequate visualization may require fluoroscopically guided oblique radiographs obtained with a soft-tissue technique.

View larger version (134K): [in this window] [in a new window] [Download PPT slide]   Figure 1.  Standard CSF shunt. Lateral radiograph of the skull (see also Fig 11) shows a typical CSF shunt (arrows). There are also four aneurysm clips (black arrowheads) near the circle of Willis, scalp (skin) staples (white arrowheads), craniotomy fixation plugs (*), and dental fillings.

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 2a.  Programmable shunt. (a) Lateral radiograph of the skull shows a Codman-Hakim programmable shunt (arrows). (b) Close-up view of the shunt shows its programmable valve (arrow).

View larger version (161K): [in this window] [in a new window] [Download PPT slide]   Figure 2b.  Programmable shunt. (a) Lateral radiograph of the skull shows a Codman-Hakim programmable shunt (arrows). (b) Close-up view of the shunt shows its programmable valve (arrow).

Subdural Drainage Catheters, Intracranial Electrodes, Subdural Electrodes, Deep Brain Stimulators, and Cerebellar Electrodes
Most acute symptomatic subdural hematomas are evacuated via craniotomy, because most of them are gelatinous clots that are difficult to extract via burr holes. Chronic subdural hematomas may be liquified and can be more easily drained by means of burr holes and subdural lavage. The use of subdural drainage catheters placed through burr holes is not common (5–8). When they are used, they are placed to diminish hematoma reaccumulation and allow the brain to reexpand. These catheters are typically straight tipped and use gravity drainage.

Intracranial (recording) electrodes placed in the brain tissue or placed in an extraaxial location are not common (Fig 3). One type of intracranial electrode is the intracranial pressure monitor (Fig 4). Intracranial pressure monitors are used to measure the pressure surrounding the brain in patients who have sustained head trauma, brain hemorrhage, or conditions in which the brain may swell. If pressure surrounding the brain becomes too high, it can decrease the blood flow to the brain and lead to brain damage.

View larger version (137K): [in this window] [in a new window] [Download PPT slide]   Figure 3.  Cross-table postoperative lateral radiograph of the skull shows recording electrodes (arrows) that lie on the brain surface bilaterally. Scalp (skin) staples and postoperative air can also be seen anteriorly under the frontal bone.

View larger version (166K): [in this window] [in a new window] [Download PPT slide]   Figure 4a.  Scout CT view of the skull (a) and CT image of the cranium (b) show a right intracranial pressure monitor in a patient with recent intracranial brain shear injuries.

View larger version (106K): [in this window] [in a new window] [Download PPT slide]   Figure 4b.  Scout CT view of the skull (a) and CT image of the cranium (b) show a right intracranial pressure monitor in a patient with recent intracranial brain shear injuries.

View larger version (124K): [in this window] [in a new window] [Download PPT slide]   Figure 5.  Close-up radiograph of the skull shows recently placed subdural recording electrodes.

View larger version (147K): [in this window] [in a new window] [Download PPT slide]   Figure 6a.  (a) Lateral radiograph of the skull shows bilateral deep brain stimulators implanted to treat Parkinson disease. (b, c) CT (b) and MR (c) images of the same patient show the stimulators in the thalamus on each side.

View larger version (142K): [in this window] [in a new window] [Download PPT slide]   Figure 6b.  (a) Lateral radiograph of the skull shows bilateral deep brain stimulators implanted to treat Parkinson disease. (b, c) CT (b) and MR (c) images of the same patient show the stimulators in the thalamus on each side.

View larger version (177K): [in this window] [in a new window] [Download PPT slide]   Figure 6c.  (a) Lateral radiograph of the skull shows bilateral deep brain stimulators implanted to treat Parkinson disease. (b, c) CT (b) and MR (c) images of the same patient show the stimulators in the thalamus on each side.

View larger version (176K): [in this window] [in a new window] [Download PPT slide]   Figure 7.  Lateral scout radiograph of the skull shows cerebellar stimulators (arrow).

View larger version (140K): [in this window] [in a new window] [Download PPT slide]   Figure 8.  Cranial plate in a 77-year-old man who suffered extensive head wounds from a mortar in the Philippines in 1944. Scout CT image of the cranium shows a metallic cranial plate that was placed emergently at a battlefield hospital. It has given the patient no trouble since the Second World War.

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 9.  Young child with recent cranial surgery for coronal suture craniosynostosis. Lateral radiograph shows a cranial plate (arrow) under the surgically created coronal suture.

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 10a.  Intracranial embolic materials. (a) Frontal radiograph of the skull shows a platinum coil (arrow) in a small, distal middle cerebral artery branch. It does not look circular, because it has conformed to the shape of the artery. (b) Massive hemorrhage not controlled by surgery in a 61-year-old man who had undergone radiation therapy for unresectable squamous cancer of the neck. Frontal view from angiography shows that the right external carotid artery has been occluded by multiple platinum coils. (c) Lateral view from angiography shows cyanoacrylate glue (arrow) that occludes an arterial venous malformation. (Courtesy of Gary Duckwiler, Los Angeles, Calif.) (d) On a CT scan, polyvinyl alcohol is difficult to see. If the patient undergoes imaging immediately after embolization, as in this case, the clot produced by polyvinyl alcohol may be seen as a linear area of increased attenuation (arrow).

View larger version (130K): [in this window] [in a new window] [Download PPT slide]   Figure 10b.  Intracranial embolic materials. (a) Frontal radiograph of the skull shows a platinum coil (arrow) in a small, distal middle cerebral artery branch. It does not look circular, because it has conformed to the shape of the artery. (b) Massive hemorrhage not controlled by surgery in a 61-year-old man who had undergone radiation therapy for unresectable squamous cancer of the neck. Frontal view from angiography shows that the right external carotid artery has been occluded by multiple platinum coils. (c) Lateral view from angiography shows cyanoacrylate glue (arrow) that occludes an arterial venous malformation. (Courtesy of Gary Duckwiler, Los Angeles, Calif.) (d) On a CT scan, polyvinyl alcohol is difficult to see. If the patient undergoes imaging immediately after embolization, as in this case, the clot produced by polyvinyl alcohol may be seen as a linear area of increased attenuation (arrow).

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 10c.  Intracranial embolic materials. (a) Frontal radiograph of the skull shows a platinum coil (arrow) in a small, distal middle cerebral artery branch. It does not look circular, because it has conformed to the shape of the artery. (b) Massive hemorrhage not controlled by surgery in a 61-year-old man who had undergone radiation therapy for unresectable squamous cancer of the neck. Frontal view from angiography shows that the right external carotid artery has been occluded by multiple platinum coils. (c) Lateral view from angiography shows cyanoacrylate glue (arrow) that occludes an arterial venous malformation. (Courtesy of Gary Duckwiler, Los Angeles, Calif.) (d) On a CT scan, polyvinyl alcohol is difficult to see. If the patient undergoes imaging immediately after embolization, as in this case, the clot produced by polyvinyl alcohol may be seen as a linear area of increased attenuation (arrow).

View larger version (150K): [in this window] [in a new window] [Download PPT slide]   Figure 10d.  Intracranial embolic materials. (a) Frontal radiograph of the skull shows a platinum coil (arrow) in a small, distal middle cerebral artery branch. It does not look circular, because it has conformed to the shape of the artery. (b) Massive hemorrhage not controlled by surgery in a 61-year-old man who had undergone radiation therapy for unresectable squamous cancer of the neck. Frontal view from angiography shows that the right external carotid artery has been occluded by multiple platinum coils. (c) Lateral view from angiography shows cyanoacrylate glue (arrow) that occludes an arterial venous malformation. (Courtesy of Gary Duckwiler, Los Angeles, Calif.) (d) On a CT scan, polyvinyl alcohol is difficult to see. If the patient undergoes imaging immediately after embolization, as in this case, the clot produced by polyvinyl alcohol may be seen as a linear area of increased attenuation (arrow).

Liquid adhesive (butyl cyanoacrylate), or glue, is also used to treat arteriovenous malformations, high-flow fistulas, and sometimes tumors (Fig 10c). The butyl cyanoacrylate is mixed with contrast material and tantalum powder to give it maximal contrast. This mixture polymerizes quickly on contact with the blood, but it can pass far distally into small vessels, which it then permanently occludes, forming a "cast" of the vascular abnormality. Unfortunately, all of the glue deposited in the vascular spaces may not be visible on radiographs, because the mixture has a tendency to settle unequally with uneven distribution of the tantalum powder.

Like the above-mentioned substances, various particulate agents, such as gelatin powder (Gelfoam; Upjohn, Kalamazoo, Mich) and polyvinyl alcohol, can be used as embolic agents to treat a variety of intracranial lesions. Particulate agents are minimally radiopaque and difficult to see at radiography or computed tomography (CT). Patients often receive particulate emboli before a definitive surgical procedure. The thrombus caused by the particles may be seen on CT scans, however, where it has high attenuation, which is the typical appearance of any other intravascular thrombus (Fig 10d).

Aneurysm Clips
Cerebral aneurysm clips are used to clamp off the neck or base of an aneurysm, depriving it of its blood supply and thereby preventing or stabilizing a serious intracranial hemorrhage (16) (Fig 11). Many aneurysm clips are applied to the side of the vessel facing the surgeon so as to require as little brain manipulation as possible. To enable the clip to be applied to the side of the vessel, these clips are designed as curved or straight, parallel flattened wires fastened together by a hinge mechanism. Other aneurysm clips are round or oval because they are designed to encircle the parent vessel. This design allows the surgeon to clip aneurysms on the side of the artery opposite that directly visible to the surgeon.

View larger version (142K): [in this window] [in a new window] [Download PPT slide]   Figure 11.  Aneurysm clips (same patient as in Fig 1). Frontal radiograph of the skull shows four aneurysm clips (black arrowheads) near the circle of Willis. There are also a right-sided CSF shunt (black arrows), scalp (skin) staples (white arrowheads), left craniotomy fixation plugs (*), and dental fillings.

Radiation Therapy Catheters, Intracranial Balloons for Drug Installation, and Carmustine Wafers
Malignant primary brain tumors and metastatic disease to the brain remain difficult challenges. Over one-half of patients with intracranial metastatic disease die of these metastases. Surgery, chemotherapy, and radiation therapy are the main treatment options for brain malignancy. Chemotherapy, administered orally or intravenously, has a limited effect against brain malignancy, because most chemotherapeutic drugs do not cross the blood-brain barrier in sufficient concentration to be effective. Radiation therapy is the primary nonsurgical treatment for brain tumors. Although external beam whole-brain radiation is potentially effective in controlling cerebral malignancy, it is severely limited by its toxic effect on adjacent normal brain tissue.

Total whole-brain radiation doses are limited to approximately 5,500 rad. To supplement whole-brain radiation, lower "boost" doses are administered by means of finely collimated external beams or implanted radioactive seeds (brachytherapy) (Fig 12). Typically, the seeds consist of iodine-125. I-125 has the advantage of ready availability and low-energy gamma radiation with limited tissue penetration. This limits the volume of normal brain tissue subjected to irradiation and diminishes the radiation exposure to other persons. The radioactive seed may be placed in the brain temporarily or permanently. Temporary seeds are left in place 5–8 days; they are introduced and removed through catheters, which are percutaneously placed in the lesion with CT guidance. The catheters are made of Teflon or plastic, and on radiographic or CT examination, they appear as tubular structures extending from a burr hole into tumor. If the iodine seeds are present in the catheters, the tip of each catheter will appear very dense.

View larger version (148K): [in this window] [in a new window] [Download PPT slide]   Figure 12.  CT scan shows intracranial brachytherapy catheters (arrow). They have a low radiodensity because they have not yet been loaded with radioactive seeds and are filled with air.

View larger version (159K): [in this window] [in a new window] [Download PPT slide]   Figure 13a.  Intracranial balloon system in a 41-year-old woman treated for glioblastoma multiforme. Lateral radiograph of the skull (a) and CT scan (b) of the cranium show an intracranial balloon system (GliaSite balloon; Proxima Therapeutics, Alpharetta, Ga) for the installation of radioactive iodine. In a, note the scalp (skin) staples and the cranial bone staples from recent intracranial surgery. In b, note the polymer wafer (arrow) impregnated with carmustine (BCNU), which shows up only as a thin white line because of its small size (1.45-cm diameter, 1-mm thickness).

View larger version (145K): [in this window] [in a new window] [Download PPT slide]   Figure 13b.  Intracranial balloon system in a 41-year-old woman treated for glioblastoma multiforme. Lateral radiograph of the skull (a) and CT scan (b) of the cranium show an intracranial balloon system (GliaSite balloon; Proxima Therapeutics, Alpharetta, Ga) for the installation of radioactive iodine. In a, note the scalp (skin) staples and the cranial bone staples from recent intracranial surgery. In b, note the polymer wafer (arrow) impregnated with carmustine (BCNU), which shows up only as a thin white line because of its small size (1.45-cm diameter, 1-mm thickness).

View larger version (127K): [in this window] [in a new window] [Download PPT slide]   Figure 14a.  Hearing aids. (a) Lateral radiograph of the cervical spine shows a hearing aid with a behind-the-ear compartment containing a battery (arrow), microphone, and amplifier. The ear mold has been removed. (b) Oblique radiograph of the skull shows a right cochlear implant. Receiver/stimulator (arrows) may look like an external hearing aid at radiography. (c) Cranial CT scan of the same patient as in b shows the cochlear implant. The receiver/stimulator (large arrow) lies in a groove cut into the mastoid portion of the temporal bone. The wire leaving the receiver/stimulator (small arrow) passes into the cochlea and forms the electrodes. The metallic portion of the cochlear apparatus is not seen because it lies in a different plane. (Courtesy of Steve Bessen, MD, Las Vegas, Nev.)

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 14b.  Hearing aids. (a) Lateral radiograph of the cervical spine shows a hearing aid with a behind-the-ear compartment containing a battery (arrow), microphone, and amplifier. The ear mold has been removed. (b) Oblique radiograph of the skull shows a right cochlear implant. Receiver/stimulator (arrows) may look like an external hearing aid at radiography. (c) Cranial CT scan of the same patient as in b shows the cochlear implant. The receiver/stimulator (large arrow) lies in a groove cut into the mastoid portion of the temporal bone. The wire leaving the receiver/stimulator (small arrow) passes into the cochlea and forms the electrodes. The metallic portion of the cochlear apparatus is not seen because it lies in a different plane. (Courtesy of Steve Bessen, MD, Las Vegas, Nev.)

View larger version (118K): [in this window] [in a new window] [Download PPT slide]   Figure 14c.  Hearing aids. (a) Lateral radiograph of the cervical spine shows a hearing aid with a behind-the-ear compartment containing a battery (arrow), microphone, and amplifier. The ear mold has been removed. (b) Oblique radiograph of the skull shows a right cochlear implant. Receiver/stimulator (arrows) may look like an external hearing aid at radiography. (c) Cranial CT scan of the same patient as in b shows the cochlear implant. The receiver/stimulator (large arrow) lies in a groove cut into the mastoid portion of the temporal bone. The wire leaving the receiver/stimulator (small arrow) passes into the cochlea and forms the electrodes. The metallic portion of the cochlear apparatus is not seen because it lies in a different plane. (Courtesy of Steve Bessen, MD, Las Vegas, Nev.)

Patients with middle-ear injuries or destruction from chronic otitis media, cholesteatoma formation, congenital malformations, or unusual tumors may be candidates for an ossicular prosthesis (24). Functional middle-ear structures may be constructed from autograft material, homograft material from cadavers, or synthetic middle-ear bone prostheses. Synthetic prostheses have become more popular. Autografts are difficult to construct, and homografts are difficult to obtain. The prostheses used for ossicular reconstruction are best evaluated with thin-section CT.

Orbital Prostheses and Intraocular Silicone Oil
Custom-made orbital prostheses are used to fill in the orbital socket in patients who have undergone enucleation. A mold of the orbital cavity is made, and then a silicone implant is fabricated to fit into the socket with minimal discomfort. For a maximal cosmetic result, the implant is tinted to match the patient’s skin. Next, an ocular prosthesis is placed into the orbital prosthesis or directly into a remnant of the globe in the case of evisceration (Fig 15a, 15b). Ocular prostheses are made of either glass or acrylic resin. Ocular prostheses are custom made for the individual patient to match the patient’s iris. Sometimes a plastic scleral shell may be used to treat patients with phthisis bulbi or microphthalmia. Most orbital, ocular, and scleral prostheses are custom made, and they vary in radiologic appearance. Usually they are easily recognized, because the associated surgical defects are obvious, as is the asymmetry when the appearance is compared with that of the opposite side.

View larger version (121K): [in this window] [in a new window] [Download PPT slide]   Figure 15a.  Orbital prostheses and silicone oil. (a) Radiograph shows an hydroxyapatite orbital prosthesis. The prosthesis is designed for the insertion of a glass eye, and the intraocular muscles can be attached to provide proper motion of the prosthetic system in concert with the motion of the other eye. (b) CT scan shows a right ocular prosthesis. (c) CT scan shows silicone oil installed in the left eye for treatment of retinal detachment.

View larger version (131K): [in this window] [in a new window] [Download PPT slide]   Figure 15b.  Orbital prostheses and silicone oil. (a) Radiograph shows an hydroxyapatite orbital prosthesis. The prosthesis is designed for the insertion of a glass eye, and the intraocular muscles can be attached to provide proper motion of the prosthetic system in concert with the motion of the other eye. (b) CT scan shows a right ocular prosthesis. (c) CT scan shows silicone oil installed in the left eye for treatment of retinal detachment.

View larger version (137K): [in this window] [in a new window] [Download PPT slide]   Figure 15c.  Orbital prostheses and silicone oil. (a) Radiograph shows an hydroxyapatite orbital prosthesis. The prosthesis is designed for the insertion of a glass eye, and the intraocular muscles can be attached to provide proper motion of the prosthetic system in concert with the motion of the other eye. (b) CT scan shows a right ocular prosthesis. (c) CT scan shows silicone oil installed in the left eye for treatment of retinal detachment.

Lacrimal Duct Stents
Epiphora is the abnormal outflow of tears onto the cheek, usually caused by blockage or stricture of the lacrimal passage. Surgery has been the conventional treatment for severe cases of epiphora, but placement of polyurethane and nitinol stents is a nonoperative way to treat this condition (26). Balloon dilation of the lacrimal system is another nonoperative treatment method. The stents can be removed if they become blocked, and they are relatively nontraumatic, but their success rates vary, and the long-term patency rates are not as encouraging as for surgical intervention. Such stents are small and easily overlooked on radiographic and CT studies. They are readily visible if looked for, particularly when an appropriate clinical history is furnished.

	Cervical Spine

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

 
Anterior and Posterior Cervical Plates
Anterior and posterior cervical fusion plates are used in cervical spine surgery for trauma, tumor, or degenerative or inflammatory conditions (27–36). In most instances, anterior cervical fusion plates are used in conjunction with supporting bone grafts (plugs) and dowels as interbody disk spacers (Fig 16). The best-known anterior cervical fusion plates are the Caspar plate (36) and the Orion plate. The term Caspar plate is sometimes used generically to describe any type of anterior cervical fusion plate. Anterior cervical plates are designed to span two or three vertebral bodies, and they are anchored to the underlying vertebral bodies with screws, which should enter the anterior cortex of each vertebral body and be seated in the posterior cortex without impinging on the cord. Ideally, the screws should not enter an adjacent end plate and should be at least 2 mm from the superior and inferior end plates.

View larger version (105K): [in this window] [in a new window] [Download PPT slide]   Figure 16a.  (a) Anterior cervical fixation plate with prefabricated bone allograft that failed to fuse. Lateral radiograph shows radiolucency around the allograft. The somewhat anterior position of the allograft and plate is typical for these plates, and it is not subluxed from its original placement position. (b) Oblique radiograph of a 27-year-old woman who had a tumor resected from the upper thoracic spine demonstrates Steffee plates and screws that were placed for spinal stabilization. Gold foil (arrows) was inserted to protect the spinal cord when the patient underwent radiation therapy.

View larger version (118K): [in this window] [in a new window] [Download PPT slide]   Figure 16b.  (a) Anterior cervical fixation plate with prefabricated bone allograft that failed to fuse. Lateral radiograph shows radiolucency around the allograft. The somewhat anterior position of the allograft and plate is typical for these plates, and it is not subluxed from its original placement position. (b) Oblique radiograph of a 27-year-old woman who had a tumor resected from the upper thoracic spine demonstrates Steffee plates and screws that were placed for spinal stabilization. Gold foil (arrows) was inserted to protect the spinal cord when the patient underwent radiation therapy.

Anterior and posterior cervical fusion plates often consist of Vitallium (Howmedica Osteonics, Allendale, NJ), an alloy of cobalt, chromium, and molybdenum, because Vitallium is less corrosive than stainless steel. It is more compatible with MR imaging than stainless steel, although it will still produce a marked magnetic susceptibility artifact. Cervical fusion plates are not a contraindication to MR imaging, but they can produce troublesome artifacts limiting the usefulness of an examination.

Posterior Cervical Spine Wiring
Use of posterior cervical spine wiring is now less common than fixation with anterior cervical fusion plates (37). Posterior cervical spine wiring is very good for limiting flexion of the spine, and it is less complicated than anterior cervical fusion and plating (Fig 17). It is poor for preventing spinal rotation and for treating patients who have anterior compression on the thecal sac. Twenty-gauge stainless steel wire is used most frequently for posterior cervical spine wiring. There are many variations in the wiring technique. These include wires under the lamina, over the lamina, and through holes drilled in the facets or spinous processes. In addition, intralaminar or spinous bone grafts are sometimes placed to supplement the wires.

View larger version (97K): [in this window] [in a new window] [Download PPT slide]   Figure 17a.  Posterior cervical spine wiring. Frontal (a) and lateral (b) radiographs of the cervical spine show posterior cervical wires from C-4 to C-7 after laminectomy. The lateral view was obtained after cervical myelography.

View larger version (103K): [in this window] [in a new window] [Download PPT slide]   Figure 17b.  Posterior cervical spine wiring. Frontal (a) and lateral (b) radiographs of the cervical spine show posterior cervical wires from C-4 to C-7 after laminectomy. The lateral view was obtained after cervical myelography.

View larger version (140K): [in this window] [in a new window] [Download PPT slide]   Figure 18a.  Odontoid fracture fixation. (a) Lateral radiograph of the cervical spine obtained after surgery shows fixation of an odontoid base fracture by an odontoid screw and a sublaminar wire between C-1 and C-2. Note the surgical drain in the posterior aspect of the neck, the gown snaps, and dental fillings. (b, c) Frontal (b) and lateral (c) radiographs of the cervical spine in a patient with rheumatoid arthritis show an occipital-spinal strut with posterior wiring used to stabilize the cervical spine and subluxation of C-1 to C-2. There is vertebral body ankylosis (arrows in c) from the rheumatoid arthritis.

View larger version (142K): [in this window] [in a new window] [Download PPT slide]   Figure 18b.  Odontoid fracture fixation. (a) Lateral radiograph of the cervical spine obtained after surgery shows fixation of an odontoid base fracture by an odontoid screw and a sublaminar wire between C-1 and C-2. Note the surgical drain in the posterior aspect of the neck, the gown snaps, and dental fillings. (b, c) Frontal (b) and lateral (c) radiographs of the cervical spine in a patient with rheumatoid arthritis show an occipital-spinal strut with posterior wiring used to stabilize the cervical spine and subluxation of C-1 to C-2. There is vertebral body ankylosis (arrows in c) from the rheumatoid arthritis.

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 18c.  Odontoid fracture fixation. (a) Lateral radiograph of the cervical spine obtained after surgery shows fixation of an odontoid base fracture by an odontoid screw and a sublaminar wire between C-1 and C-2. Note the surgical drain in the posterior aspect of the neck, the gown snaps, and dental fillings. (b, c) Frontal (b) and lateral (c) radiographs of the cervical spine in a patient with rheumatoid arthritis show an occipital-spinal strut with posterior wiring used to stabilize the cervical spine and subluxation of C-1 to C-2. There is vertebral body ankylosis (arrows in c) from the rheumatoid arthritis.

Unlike cervical collars, cervical braces are designed for the long-term treatment of cervical spine fractures. They consist of chin and occipital supports that are connected to a thoracic vest by metal rods. Cervical braces do provide good prevention against harmful flexion, but they are not as effective in preventing harmful extension.

The halo vest contains a metallic ring (the halo) that is attached to the outer table of the skull by screws (39–41) (Fig 19). The halo is connected to a padded fiberglass or plastic thoracic cast by metal rods (the struts), which hold up the patient’s head. Although halo vests involve placement of screws into the skull and are a major undertaking for both the patient and the physician, they provide the best long-term fixation of the cervical spine. They are especially indicated for unstable fractures and dislocations and work best in the upper cervical spine.

View larger version (111K): [in this window] [in a new window] [Download PPT slide]   Figure 19a.  Halo vest and brace. (a, b) Frontal (a) and lateral (b) views of a halo vest and brace. Four metallic uprights connect the halo ring around the skull to the vest. (c, d) Frontal (c) and lateral (d) radiographs of the skull show head tongs used to stabilize the head and neck in a patient with a cervical spine fracture. One or more screws penetrate the outer table of the skull on each side. They are connected to each other by horizontal or vertical bars on each side that are attached to an external traction device.

View larger version (112K): [in this window] [in a new window] [Download PPT slide]   Figure 19b.  Halo vest and brace. (a, b) Frontal (a) and lateral (b) views of a halo vest and brace. Four metallic uprights connect the halo ring around the skull to the vest. (c, d) Frontal (c) and lateral (d) radiographs of the skull show head tongs used to stabilize the head and neck in a patient with a cervical spine fracture. One or more screws penetrate the outer table of the skull on each side. They are connected to each other by horizontal or vertical bars on each side that are attached to an external traction device.

View larger version (156K): [in this window] [in a new window] [Download PPT slide]   Figure 19c.  Halo vest and brace. (a, b) Frontal (a) and lateral (b) views of a halo vest and brace. Four metallic uprights connect the halo ring around the skull to the vest. (c, d) Frontal (c) and lateral (d) radiographs of the skull show head tongs used to stabilize the head and neck in a patient with a cervical spine fracture. One or more screws penetrate the outer table of the skull on each side. They are connected to each other by horizontal or vertical bars on each side that are attached to an external traction device.

View larger version (113K): [in this window] [in a new window] [Download PPT slide]   Figure 19d.  Halo vest and brace. (a, b) Frontal (a) and lateral (b) views of a halo vest and brace. Four metallic uprights connect the halo ring around the skull to the vest. (c, d) Frontal (c) and lateral (d) radiographs of the skull show head tongs used to stabilize the head and neck in a patient with a cervical spine fracture. One or more screws penetrate the outer table of the skull on each side. They are connected to each other by horizontal or vertical bars on each side that are attached to an external traction device.

	Thoracic and Lumbar Spine

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

Posterior Spinal Instrumentation.— Posterior spinal instrumentation is preferred over anterior spinal instrumentation in the thoracic and lumbar regions, because it allows easier decompression and visualization of neural elements (42–56). The posterior surgical approach is much simpler and safer in general than an anterior approach going through the neck, chest, or abdomen. On the other hand, the anterior approach is generally preferred for spinal surgery in the cervical region for two reasons. First, posterior instrumentation in the cervical spine is usually limited, because the vertebrae in the cervical spine are smaller, as is the volume of the soft tissue. Second, the substantial implants used posteriorly in the thoracic and lumbar regions are too large to be used in the cervical spine. Mechanically, they would not safely fit in the cervical region, and the degree of support they provide for the thoracic and lumbar regions is not needed in the cervical spine.

Surgery to fuse the lumbar spine has been performed for more than 100 years. The techniques used for the earliest procedures involved only bone grafting in situ, and they are still applicable today. Currently, it is quite common to combine bone grafting with the use of spinal fixation apparatus to improve fusion rates. Successful bone grafts are necessary for the ultimate success of spinal surgery. If the bone grafting and eventual fusion are not successful, the spinal fixation apparatus will ultimately fail. Spinal implants are very useful, however, for they often permit less extensive surgery, providing immediate spine stability, improved fusion rates, and rapid patient mobilization and rehabilitation.

One of the first practical applications of spinal fixation apparatus was the use by Luque of sublaminar wires attached to anchor rods for thoracic and lumbar spine posterior stabilization (Fig 20). Although this technique provided very secure fixation, it had a relatively high risk of associated neurologic complications. In Luque’s original technique, the wires were "blindly" passed under the lamina at surgery with no direct visualization of the spinal dura neurologic elements. The original technique has for the most part been replaced with use of segmental wires passed through the base of the spinous processes. The new technique is easier for the surgeon, and it avoids injury to the spinal cord and its nerve roots. In a further modification of the original sublaminar wire technique, rectangular fixation devices (Luque and Hartshill rectangles) or metallic buttons (Wisconsin posterior spinal wiring) are used with sublaminar wires designed to hold the metallic rectangles or buttons to adjacent vertebrae (Figs 21, 22).

View larger version (93K): [in this window] [in a new window] [Download PPT slide]   Figure 20.  Bilateral Luque rods. Frontal radiograph shows bilateral Luque rods that were placed to stabilize the spine for treatment of scoliosis. Note the rod fractures at the T-12 level.

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 21.  Hartshill rectangle used to treat degenerative disease in the lower lumbar spine. Frontal radiograph shows a Hartshill rectangle with surrounding bone fusion. The wires through the sacral lamina are broken, which is not a problem if there is solid bone fusion.

View larger version (153K): [in this window] [in a new window] [Download PPT slide]   Figure 22a.  Frontal (a) and lateral (b) radiographs of the lower thoracic spine show Wisconsin posterior spinal wiring. The wires go under the lamina and are connected to buttons that sit external to the posterior elements of the spine.

View larger version (143K): [in this window] [in a new window] [Download PPT slide]   Figure 22b.  Frontal (a) and lateral (b) radiographs of the lower thoracic spine show Wisconsin posterior spinal wiring. The wires go under the lamina and are connected to buttons that sit external to the posterior elements of the spine.

View larger version (37K): [in this window] [in a new window] [Download PPT slide]   Figure 23a.  Harrington rods for posterior spinal fixation. (a) Photograph of Harrington rods shows their flanged ends and hooks. The hooks on these particular rods are designed for distraction. (b) Lateral radiograph of the thoracolumbar junction shows a Harrington rod stabilizing a vertebral body fracture. Hooks (thick arrows) are used to anchor the rod ends in the lamina. Segmental wires around the lamina (thin arrow) also augment the fixation.

View larger version (118K): [in this window] [in a new window] [Download PPT slide]   Figure 23b.  Harrington rods for posterior spinal fixation. (a) Photograph of Harrington rods shows their flanged ends and hooks. The hooks on these particular rods are designed for distraction. (b) Lateral radiograph of the thoracolumbar junction shows a Harrington rod stabilizing a vertebral body fracture. Hooks (thick arrows) are used to anchor the rod ends in the lamina. Segmental wires around the lamina (thin arrow) also augment the fixation.

View larger version (156K): [in this window] [in a new window] [Download PPT slide]   Figure 24a.  Brantigan interbody vertebral cage. (a, b) Frontal (a) and lateral (b) radiographs of the lumbar spine in two different patients show a laminectomy from L-2 to S-1. There are bilateral Steffee pedicle plates and screws at L-2 to L-4 with two side-by-side high-density carbon fiber Brantigan interbody vertebral cages (arrows) at L-2 to L-3. (c) Photograph of a Brantigan interbody vertebral cage shows its grooves for bone incorporation into the vertebrae and a metallic marker (arrow) for identification on radiographs.

View larger version (155K): [in this window] [in a new window] [Download PPT slide]   Figure 24b.  Brantigan interbody vertebral cage. (a, b) Frontal (a) and lateral (b) radiographs of the lumbar spine in two different patients show a laminectomy from L-2 to S-1. There are bilateral Steffee pedicle plates and screws at L-2 to L-4 with two side-by-side high-density carbon fiber Brantigan interbody vertebral cages (arrows) at L-2 to L-3. (c) Photograph of a Brantigan interbody vertebral cage shows its grooves for bone incorporation into the vertebrae and a metallic marker (arrow) for identification on radiographs.

View larger version (87K): [in this window] [in a new window] [Download PPT slide]   Figure 24c.  Brantigan interbody vertebral cage. (a, b) Frontal (a) and lateral (b) radiographs of the lumbar spine in two different patients show a laminectomy from L-2 to S-1. There are bilateral Steffee pedicle plates and screws at L-2 to L-4 with two side-by-side high-density carbon fiber Brantigan interbody vertebral cages (arrows) at L-2 to L-3. (c) Photograph of a Brantigan interbody vertebral cage shows its grooves for bone incorporation into the vertebrae and a metallic marker (arrow) for identification on radiographs.

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 25a.  Frontal (a) and lateral (b) radiographs of the lumbar spine show pedicle screws at L-3 and L-5 with spanning rods on each side. There is an anterior allograft bone strut used to treat metastatic neuroblastoma in the L-4 vertebral body. Note the bone strut crosses both the pathologic vertebral body as well as its adjacent disks. The anterior position of the bone strut is typical for these struts, and it does not represent migration after surgery.

View larger version (91K): [in this window] [in a new window] [Download PPT slide]   Figure 25b.  Frontal (a) and lateral (b) radiographs of the lumbar spine show pedicle screws at L-3 and L-5 with spanning rods on each side. There is an anterior allograft bone strut used to treat metastatic neuroblastoma in the L-4 vertebral body. Note the bone strut crosses both the pathologic vertebral body as well as its adjacent disks. The anterior position of the bone strut is typical for these struts, and it does not represent migration after surgery.

Malignant disease, severe infectious disease, or major trauma to the spine may destroy one or more vertebral bodies. This destruction may be treated with vertebral body resection (corpectomy) and bone grafting combined with placement of a vertebral "cage" (Figs 25, 26). The cage may be freestanding or associated with a lateral, anterior, or posterior fixator to give the reconstructed area more strength (Fig 26). These cages are generically called titanium interbody spacers. They are usually manufactured from titanium, which has good strength and good biocompatibility and also produces fewer artifacts on MR images compared with other metals such as stainless steel. Vertebral cages have a hollow, threaded, cylindrical structure with teeth on both sides for fixation to vertebral end plates superiorly and inferiorly. The hollow center is usually filled with autograft or allograft bone material to strengthen the fixation and provide later fusion.

View larger version (139K): [in this window] [in a new window] [Download PPT slide]   Figure 26a.  Harms vertebral body cage. Frontal (a) and lateral (b) radiographs of the lower thoracic spine show a Harms vertebral body cage and a side plate and screws used to treat a spinal tumor.

View larger version (156K): [in this window] [in a new window] [Download PPT slide]   Figure 26b.  Harms vertebral body cage. Frontal (a) and lateral (b) radiographs of the lower thoracic spine show a Harms vertebral body cage and a side plate and screws used to treat a spinal tumor.

View larger version (147K): [in this window] [in a new window] [Download PPT slide]   Figure 27.  Frontal radiograph shows two Bagby and Kuslich threaded screw-in metallic vertebral cages that were used to treat degenerative lumbar spine disease.

Vertebroplasty.— Vertebroplasty is designed to provide pain relief from benign osteoporotic compression fractures or less common, destructive vertebral lesions (57). Methyl methacrylate is injected directly into a vertebral body to strengthen the bone structure of the vertebrae and immobilize fractures, which provides immediate pain relief. If the patients are properly selected and the procedure goes well, vertebroplasty is a dramatic technique. Patients who are bedridden or wheelchair bound have such relief from the chronic pain of vertebral collapse that they frequently ask to walk out of the hospital. Vertebroplasty is a serious procedure, and patients must be carefully selected. Because the methyl methacrylate is mixed with barium sulfate, it is visible on radiographs and on cross-sectional images (Fig 28).

View larger version (132K): [in this window] [in a new window] [Download PPT slide]   Figure 28.  Lateral radiograph of the lumbar spine in a 75-year-old woman with osteoporosis shows vertebroplasty. The patient had experienced severe back pain after lifting a heavy bag and had sustained a fracture. Vertebroplasty was performed at L-3 to relieve unremitting pain caused by the compression fracture.

Spinal Column Stimulators, Bone Stimulators, Intrathecal Drug Delivery Pumps, and Sacral Stimulators
Patients with intractable pain and muscle spasms are difficult to treat. They often become dependent on large doses of pain medication and cannot perform normal activities of daily living. Some patients receive considerable pain relief through electrical stimulation of the spinal cord or dorsal nerve roots. Devices designed for this function are the transcutaneous electrical neural stimulation (TENS) and dorsal column stimulation (DCS) units (58–62). The TENS unit consists of stimulating electrodes in externally placed patches similar to those used in electrocardiography. A DCS unit is placed percutaneously or surgically in the dorsal epidural space or subarachnoid space near a dorsal root ganglion, with a battery pack (pulse generator) placed in the subcutaneous tissues of the back. The battery pack, stimulator wires, and electrodes are partially metallic and easily seen on radiographs (Fig 29a, 29b). The electrodes are often enmeshed in Teflon or a plastic matrix, and they look like a set of unconnected metallic dots on radiographs. Unfortunately, in many patients the relief from pain and spasticity provided by these devices decreases with time, possibly because the electrodes are eventually enveloped by reactive fibrous tissues.

View larger version (60K): [in this window] [in a new window] [Download PPT slide]   Figure 29a.  Spinal column treatment devices in different patients. (a, b) Frontal (a) and lateral (b) radiographs show the presence of a dorsal column stimulation unit in the upper cervical spine. Skin staples from the recent surgery are seen, and there is congenital fusion of the C-5 and C-6 vertebral bodies. (c) Frontal radiograph of the lumbar spine in another patient shows a bone stimulator. Battery pack overlies the right 12th rib, and there are wires going to electrodes in the bony fusion masses bilaterally. A laminectomy had been performed from L-2 to S-1 with bilateral pedicle screws and a pedicle plate on the right and a connecting pedicle rod on the left. There are also two Brantigan vertebral cages at the L-5 to S-1 disk space. (d) Lateral radiograph of another patient shows an intrathecal drug delivery catheter (top arrow) that was placed in the lower thoracic subarachnoid space. The catheter goes down the spinal canal and exits to an anterior abdominal delivery pump, a portion of which (bottom arrow) is evident. (e, f) Frontal (e) and lateral (f) radiographs of the pelvis and sacrum in another patient show a sacral stimulator.

View larger version (108K): [in this window] [in a new window] [Download PPT slide]   Figure 29b.  Spinal column treatment devices in different patients. (a, b) Frontal (a) and lateral (b) radiographs show the presence of a dorsal column stimulation unit in the upper cervical spine. Skin staples from the recent surgery are seen, and there is congenital fusion of the C-5 and C-6 vertebral bodies. (c) Frontal radiograph of the lumbar spine in another patient shows a bone stimulator. Battery pack overlies the right 12th rib, and there are wires going to electrodes in the bony fusion masses bilaterally. A laminectomy had been performed from L-2 to S-1 with bilateral pedicle screws and a pedicle plate on the right and a connecting pedicle rod on the left. There are also two Brantigan vertebral cages at the L-5 to S-1 disk space. (d) Lateral radiograph of another patient shows an intrathecal drug delivery catheter (top arrow) that was placed in the lower thoracic subarachnoid space. The catheter goes down the spinal canal and exits to an anterior abdominal delivery pump, a portion of which (bottom arrow) is evident. (e, f) Frontal (e) and lateral (f) radiographs of the pelvis and sacrum in another patient show a sacral stimulator.

View larger version (94K): [in this window] [in a new window] [Download PPT slide]   Figure 29c.  Spinal column treatment devices in different patients. (a, b) Frontal (a) and lateral (b) radiographs show the presence of a dorsal column stimulation unit in the upper cervical spine. Skin staples from the recent surgery are seen, and there is congenital fusion of the C-5 and C-6 vertebral bodies. (c) Frontal radiograph of the lumbar spine in another patient shows a bone stimulator. Battery pack overlies the right 12th rib, and there are wires going to electrodes in the bony fusion masses bilaterally. A laminectomy had been performed from L-2 to S-1 with bilateral pedicle screws and a pedicle plate on the right and a connecting pedicle rod on the left. There are also two Brantigan vertebral cages at the L-5 to S-1 disk space. (d) Lateral radiograph of another patient shows an intrathecal drug delivery catheter (top arrow) that was placed in the lower thoracic subarachnoid space. The catheter goes down the spinal canal and exits to an anterior abdominal delivery pump, a portion of which (bottom arrow) is evident. (e, f) Frontal (e) and lateral (f) radiographs of the pelvis and sacrum in another patient show a sacral stimulator.

View larger version (105K): [in this window] [in a new window] [Download PPT slide]   Figure 29d.  Spinal column treatment devices in different patients. (a, b) Frontal (a) and lateral (b) radiographs show the presence of a dorsal column stimulation unit in the upper cervical spine. Skin staples from the recent surgery are seen, and there is congenital fusion of the C-5 and C-6 vertebral bodies. (c) Frontal radiograph of the lumbar spine in another patient shows a bone stimulator. Battery pack overlies the right 12th rib, and there are wires going to electrodes in the bony fusion masses bilaterally. A laminectomy had been performed from L-2 to S-1 with bilateral pedicle screws and a pedicle plate on the right and a connecting pedicle rod on the left. There are also two Brantigan vertebral cages at the L-5 to S-1 disk space. (d) Lateral radiograph of another patient shows an intrathecal drug delivery catheter (top arrow) that was placed in the lower thoracic subarachnoid space. The catheter goes down the spinal canal and exits to an anterior abdominal delivery pump, a portion of which (bottom arrow) is evident. (e, f) Frontal (e) and lateral (f) radiographs of the pelvis and sacrum in another patient show a sacral stimulator.

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 29e.  Spinal column treatment devices in different patients. (a, b) Frontal (a) and lateral (b) radiographs show the presence of a dorsal column stimulation unit in the upper cervical spine. Skin staples from the recent surgery are seen, and there is congenital fusion of the C-5 and C-6 vertebral bodies. (c) Frontal radiograph of the lumbar spine in another patient shows a bone stimulator. Battery pack overlies the right 12th rib, and there are wires going to electrodes in the bony fusion masses bilaterally. A laminectomy had been performed from L-2 to S-1 with bilateral pedicle screws and a pedicle plate on the right and a connecting pedicle rod on the left. There are also two Brantigan vertebral cages at the L-5 to S-1 disk space. (d) Lateral radiograph of another patient shows an intrathecal drug delivery catheter (top arrow) that was placed in the lower thoracic subarachnoid space. The catheter goes down the spinal canal and exits to an anterior abdominal delivery pump, a portion of which (bottom arrow) is evident. (e, f) Frontal (e) and lateral (f) radiographs of the pelvis and sacrum in another patient show a sacral stimulator.

View larger version (50K): [in this window] [in a new window] [Download PPT slide]   Figure 29f.  Spinal column treatment devices in different patients. (a, b) Frontal (a) and lateral (b) radiographs show the presence of a dorsal column stimulation unit in the upper cervical spine. Skin staples from the recent surgery are seen, and there is congenital fusion of the C-5 and C-6 vertebral bodies. (c) Frontal radiograph of the lumbar spine in another patient shows a bone stimulator. Battery pack overlies the right 12th rib, and there are wires going to electrodes in the bony fusion masses bilaterally. A laminectomy had been performed from L-2 to S-1 with bilateral pedicle screws and a pedicle plate on the right and a connecting pedicle rod on the left. There are also two Brantigan vertebral cages at the L-5 to S-1 disk space. (d) Lateral radiograph of another patient shows an intrathecal drug delivery catheter (top arrow) that was placed in the lower thoracic subarachnoid space. The catheter goes down the spinal canal and exits to an anterior abdominal delivery pump, a portion of which (bottom arrow) is evident. (e, f) Frontal (e) and lateral (f) radiographs of the pelvis and sacrum in another patient show a sacral stimulator.

Intrathecal drug delivery pumps are another technique for treating patients with intractable pain and muscle spasticity (61). These pumps consist of a catheter placed in the spinal subarachnoid space, usually in the lumbar area, and a battery-operated pump located in a nearby subcutaneous pocket (Fig 29d). The pump is attached to the catheter, and it delivers a carefully controlled volume of medication to the CSF. Because the pump lies in a convenient subcutaneous location, it can easily be refilled via a needle inserted into its access port through the skin. Intrathecal drug delivery pumps are most commonly used to deliver intrathecal morphine to ameliorate intractable pain in cancer patients. Other medications, such as local anesthetics and chemotherapeutic agents, may be infused in a similar manner. Similar chemotherapeutic infusion pumps are sometimes used in the abdomen and pelvis to deliver chemotherapeutic agents into the vascular system that feeds an abdominal or pelvic tumor mass.

Sacral plexus nerve stimulation is an experimental technique for long-term treatment of patients with bladder dysfunction (63). One or more wire electrodes are placed in the vicinity of the sacral roots at the level of the sacral foramina (Fig 29e, 29f). The wires are connected to an external stimulator. Proper placement of the stimulating wires varies depending on the patient and the problem being addressed. S-3 nerve root stimulation, for example, sometimes produces a contraction of the levator muscles, the detrusor musculature, the urethral sphincter, and plantar flexion of the great toes. The sacral root on each side that gives the best subjective patient response is used for the stimulation.

	Mandible and Maxilla: Dental and Facial Implant Devices

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

 
A wide variety of devices can be placed within and throughout the maxillomandibular regions in addition to the oral cavity (Fig 30). General dentists and specialists (prosthodontists, periodontists, and oral surgeons) use restorative and reconstructive prosthetic devices manufactured from alloplastic materials, acrylics, ceramics, porcelains, and metals (elemental and alloys). In dentistry, most alloys contain varying combinations of gold, platinum, palladium, silver, cobalt, aluminum, copper, chromium, zinc, and mercury. Except for aluminum, all metals and metal alloys used in dentistry are radiopaque.

View larger version (119K): [in this window] [in a new window] [Download PPT slide]   Figure 30a.  Dental devices. (a) Panoramic radiograph shows bone plates with screws (A) and bone ligature wires (B). Note also the multiple dental alloy restorations (amalgam fillings). (b) Panoramic radiograph shows root canal fillings with denture retention posts (A) and porcelain denture teeth with pins (B). (c) Frontal radiograph of the mandible shows a temporomandibular joint prosthetic condyle implant (A), orthodontic arch bars (B), porcelain veneer crowns (caps) (C), and fixation screws (bone screws) (D). (d) Radiograph shows a cubic zirconia crown (*). Note the opacity of the zirconia substrate. The zirconia is surrounded by porcelain (horizontal arrowheads). Note the endodontic root canal with gutta percha (arrows), a radiopaque rubber, in the tooth next to it. The light shade of the teeth (vertical arrowheads) next to the tooth containing the cubic zirconia crown shows that they have been restored with a composite acrylic restoration.

View larger version (143K): [in this window] [in a new window] [Download PPT slide]   Figure 30b.  Dental devices. (a) Panoramic radiograph shows bone plates with screws (A) and bone ligature wires (B). Note also the multiple dental alloy restorations (amalgam fillings). (b) Panoramic radiograph shows root canal fillings with denture retention posts (A) and porcelain denture teeth with pins (B). (c) Frontal radiograph of the mandible shows a temporomandibular joint prosthetic condyle implant (A), orthodontic arch bars (B), porcelain veneer crowns (caps) (C), and fixation screws (bone screws) (D). (d) Radiograph shows a cubic zirconia crown (*). Note the opacity of the zirconia substrate. The zirconia is surrounded by porcelain (horizontal arrowheads). Note the endodontic root canal with gutta percha (arrows), a radiopaque rubber, in the tooth next to it. The light shade of the teeth (vertical arrowheads) next to the tooth containing the cubic zirconia crown shows that they have been restored with a composite acrylic restoration.

View larger version (114K): [in this window] [in a new window] [Download PPT slide]   Figure 30c.  Dental devices. (a) Panoramic radiograph shows bone plates with screws (A) and bone ligature wires (B). Note also the multiple dental alloy restorations (amalgam fillings). (b) Panoramic radiograph shows root canal fillings with denture retention posts (A) and porcelain denture teeth with pins (B). (c) Frontal radiograph of the mandible shows a temporomandibular joint prosthetic condyle implant (A), orthodontic arch bars (B), porcelain veneer crowns (caps) (C), and fixation screws (bone screws) (D). (d) Radiograph shows a cubic zirconia crown (*). Note the opacity of the zirconia substrate. The zirconia is surrounded by porcelain (horizontal arrowheads). Note the endodontic root canal with gutta percha (arrows), a radiopaque rubber, in the tooth next to it. The light shade of the teeth (vertical arrowheads) next to the tooth containing the cubic zirconia crown shows that they have been restored with a composite acrylic restoration.

View larger version (121K): [in this window] [in a new window] [Download PPT slide]   Figure 30d.  Dental devices. (a) Panoramic radiograph shows bone plates with screws (A) and bone ligature wires (B). Note also the multiple dental alloy restorations (amalgam fillings). (b) Panoramic radiograph shows root canal fillings with denture retention posts (A) and porcelain denture teeth with pins (B). (c) Frontal radiograph of the mandible shows a temporomandibular joint prosthetic condyle implant (A), orthodontic arch bars (B), porcelain veneer crowns (caps) (C), and fixation screws (bone screws) (D). (d) Radiograph shows a cubic zirconia crown (*). Note the opacity of the zirconia substrate. The zirconia is surrounded by porcelain (horizontal arrowheads). Note the endodontic root canal with gutta percha (arrows), a radiopaque rubber, in the tooth next to it. The light shade of the teeth (vertical arrowheads) next to the tooth containing the cubic zirconia crown shows that they have been restored with a composite acrylic restoration.

Strength is an additional benefit of using fillers in composite acrylic resins (64,65). The esthetic value of adding fillers to color composite restorations for an ideal match with natural tooth dentin or enamel is complemented by the ability of these fillers to enhance resistance to destructive masticatory forces. As a result, this type of dental restoration provides a formidable challenge to the dominant position once held by amalgam alloys in restorative dentistry. Esthetics and strength make composite acrylic resins the restoration ma-terial of choice while providing an ideal contrast medium for the radiographic detection and diagnosis of dental disorders.

In combination with chromium alloys, removable denture prosthetic devices of resin acrylic bases and teeth (or porcelain teeth) provide an economical alternative for the partially edentu-lous individual. A semipermanent appliance can provide long-term temporomandibular joint stability for patients suffering from masticatory-related temporomandibular disease or craniofacial pain. Although the acrylics are, to varying degrees, radiolucent, the metal framework is intensely radiopaque.

Porcelain dental materials, to an extent, are stronger and more opaque than acrylic materials. Their radiopacity is similar to that of natural tooth enamel (Fig 30d). Unfortunately, they are much more brittle. Dental porcelains are widely used and, like composite acrylics, may be altered in color to conform to the "natural" look of dentin or enamel. They have become an integral component to crowns, bridges, veneers, and dentures. To compensate for their brittleness in crown restorations and fixed partial dentures, dental porcelains have been used with an underlying substructure of metal alloys, such as gold, palladium, or nickel and beryllium. For fixed partial dentures, metal alloys have been necessary to acquire the strength needed to span edentulous areas.

The latest generation of reinforced composites, soft porcelains, and ceramic substructures has dynamically changed the options available for both the doctor and the patient. Lucite-reinforced composites and soft porcelains are now directly bonded to the tooth with resin bonding agents that are almost totally resistant to the effects of washout from fluids within the oral cavity. Use of ceramic substructures such as cubic zirconia (zirconium oxide) allows for conventional placement with cements, gives the strength once provided by metal alloys, and yet meets the esthetic and cosmetic demands of patients. Ceramic substructures have totally replaced all metals and metal alloys for fillings, inlays, onlays, cosmetic veneers, crowns, and fixed partial dentures (bridges). The synergy of these composites or porcelains with bonding resins has yielded dental devices with such a natural look and feel that they are virtually indistinguishable from natural human teeth clinically or radiographically (Fig 30d). This lessens the challenge in the diagnosis of oral disease.

Amalgam materials consist of an alchemy of two or more metals. Dental amalgam is intensely radiopaque and is composed primarily of mercury (>50%). The leading secondary element is silver, followed by trace elements that may include copper, tin, and zinc. These trace elements are used to aid against expansion and corrosion. Until recently, dental amalgams enjoyed universal acceptance. Concern has been expressed about potential mercury toxicity found in dental amalgam. Systemic absorption of mercury from dental amalgams has become a topic of controversy. Although scientific evidence that dental mercury amalgam presents a danger remains inconclusive, the much-heated debate within the dental profession continues. In light of the alleged risk to the medical and dental health of patients as well the high probability of an unsatisfactory esthetic outcome with its use, the future value of amalgam as a dental material is uncertain.

Facial Implant Devices
Metals and metal alloys may be used as implant devices whether in the maxilla, the mandible, or the temporomandibular joint connecting the two (64,65). In addition, they are found in oral facial reconstruction. Metal and metal alloys, such as stainless steel, cobalt-chromium-molybdenum alloy, titanium, and titanium-aluminum-vanadium alloy, are the foundation for either subperiosteal, transosteal, or endosseous types of implant devices and are intensely opaque on radiographs. Precision in their placement is critical, and for this reason, CT may be used as an adjunct to the surgical procedure.

Ceramics offer excellent biocompatibility and are often combined with metals and metal alloys in the construction of oral facial devices. A popular ceramic is hydroxyapatite, a bioactive-type material that contains calcium, phosphate, and hydroxyl ions [Ca₁₀(PO₄)₆(OH)₂]. Another popular ceramic form is bioactive glass made from silicon, calcium, sodium, and phosphorus (Bioglass, Biogran, Perioglas, Nova Bonce, and Nova Bone are particulate forms of bioactive glass). In medical care, Nova Bone is used by orthopedic surgeons in procedures such as spinal fusion, revision arthroplasty, and general defect fillings. In dentistry, it is used by oral surgeons for craniofacial and maxillofacial surgery. Perioglas and Biogran are used primarily in the treatment of periodontal defects caused by periodontal disease. Ceramics have a crystalline form with a specific lattice configuration that may be fused to an underlying metallic substructure. This combination provides strength and durability with an exceptional bonding mechanism both to the metal and to bone. For this reason, ceramics are also beneficial without an underlying metal or metal alloy substructure.

Bioactive ceramics are used as an implant material for augmenting alveolar ridges or filling bone defects. Granular shapes allow for easy placement into osseous defects. Being osteogenic, hydroxyapatite and Bioglass are negatively charged. This negative charge results in their ability to stimulate the production of new bone where bone has been lost, either through disease or surgical intervention. An excellent substitute for natural bone, ceramics act as a stimulant and scaffold for the production of new bone. Bioactive ceramics have a radiopacity similar to that of dense bone, allowing for the verification of surgical success.

	Neck

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

 
Gastric and Tracheal Tubes
Some medical apparatus goes through the neck en route to thoracic and abdominal structures (66–68). Endotracheal tubes, tracheostomy tubes, orogastric tubes, nasogastric tubes, oral airways, and feeding tubes are common findings on cervical spine and chest radiographs (Fig 31). Because these tubes start from similar locations and go through neighboring structures, it is often difficult to differentiate between tracheal and gastric tubes, especially on bedside chest radiographs. Both may be placed through the nose, and they overlap in size and appearance. Small tubes, however—especially those less than 5 mm in diameter—are usually feeding tubes. Endotracheal and nasogastric tubes are composed of radiolucent materials, but the manufacturers usually add a barium stripe or other high-density stripe to make the tube easily visible on radiographs, although it may be hard to differentiate an endotracheal tube from a nasogastric tube. Endotracheal tubes can be more easily recognized on lateral views because they lie anterior to gastric tubes and within the airway. They often can be identified if they are seen to pass between the vocal cords.

View larger version (126K): [in this window] [in a new window] [Download PPT slide]   Figure 31a.  Gastric and tracheal tubes. (a) Lateral radiograph of the head and neck in a child with severe intracranial and cervical spine injuries shows the presence of bilateral cranial stabilization tongs, an endotracheal tube, a nasogastric tube, and a feeding tube (entering via the nose). (b, c) Frontal (b) and lateral (c) radiographs of the chest and neck in a different patient show the incorrect placement of a tracheostomy tube. The tip of the tube is to the left of the trachea in b and anterior to the trachea (arrow) in c. (d) Nasotracheal and orogastric tubes. Lateral radiograph shows a nasotracheal tube that is larger and anterior in the expected location of the trachea. The orogastric tube is smaller (arrow) and posterior.

View larger version (104K): [in this window] [in a new window] [Download PPT slide]   Figure 31b.  Gastric and tracheal tubes. (a) Lateral radiograph of the head and neck in a child with severe intracranial and cervical spine injuries shows the presence of bilateral cranial stabilization tongs, an endotracheal tube, a nasogastric tube, and a feeding tube (entering via the nose). (b, c) Frontal (b) and lateral (c) radiographs of the chest and neck in a different patient show the incorrect placement of a tracheostomy tube. The tip of the tube is to the left of the trachea in b and anterior to the trachea (arrow) in c. (d) Nasotracheal and orogastric tubes. Lateral radiograph shows a nasotracheal tube that is larger and anterior in the expected location of the trachea. The orogastric tube is smaller (arrow) and posterior.

View larger version (123K): [in this window] [in a new window] [Download PPT slide]   Figure 31c.  Gastric and tracheal tubes. (a) Lateral radiograph of the head and neck in a child with severe intracranial and cervical spine injuries shows the presence of bilateral cranial stabilization tongs, an endotracheal tube, a nasogastric tube, and a feeding tube (entering via the nose). (b, c) Frontal (b) and lateral (c) radiographs of the chest and neck in a different patient show the incorrect placement of a tracheostomy tube. The tip of the tube is to the left of the trachea in b and anterior to the trachea (arrow) in c. (d) Nasotracheal and orogastric tubes. Lateral radiograph shows a nasotracheal tube that is larger and anterior in the expected location of the trachea. The orogastric tube is smaller (arrow) and posterior.

View larger version (162K): [in this window] [in a new window] [Download PPT slide]   Figure 31d.  Gastric and tracheal tubes. (a) Lateral radiograph of the head and neck in a child with severe intracranial and cervical spine injuries shows the presence of bilateral cranial stabilization tongs, an endotracheal tube, a nasogastric tube, and a feeding tube (entering via the nose). (b, c) Frontal (b) and lateral (c) radiographs of the chest and neck in a different patient show the incorrect placement of a tracheostomy tube. The tip of the tube is to the left of the trachea in b and anterior to the trachea (arrow) in c. (d) Nasotracheal and orogastric tubes. Lateral radiograph shows a nasotracheal tube that is larger and anterior in the expected location of the trachea. The orogastric tube is smaller (arrow) and posterior.

Most of the time, endotracheal intubation is lifesaving. Unfortunately, it can also be life threatening if the tube is not in the proper position. The location of the endotracheal tube tip should always be ascertained. When the neck of an adult is in a neutral position, the tip of the tube should be approximately 5 cm above the tracheal carina at about the level of the aortic knob. In children, depending on their size, the tube tip should be 2–5 cm above the tracheal carina. In general, the tracheal carina is just distal to the level of the aortic arch. If the tip of the endotracheal tube is just above the aortic knob, it is in good position, midway between the vocal cords and the carina. This position allows safe excursion of 2 cm upward or downward when the patient flexes or extends the neck. Tubes tend to descend when the neck is flexed and ascend when it is extended. If the endotracheal tube has a cuff, the balloon should not be inflated to more than one and a half times the diameter of the trachea. Prolonged overextension of the endotracheal cuff can lead to ischemic necrosis of the tracheal cartilage and tracheomalacia.

Tracheostomy tubes are composed of dense plastic or metal and are readily visible on most images. In an ideal situation, they are placed by an experienced surgeon for a patient who requires prolonged respiratory therapy or to provide an airway for a patient who has suffered grievous injury to the upper airway, neck, or face. Tracheostomy tubes are usually inserted between the second and third tracheal rings. They can be placed emergently, but in some emergency situations, a cricothyroid tube is used instead. Cricothyroid tubes are easier and quicker to insert than tracheostomy tubes, but they carry a higher risk of vocal cord damage. They may be difficult to distinguish from a tracheostomy tube unless one is provided with an adequate history of a cricothyroid tube insertion.

Vagus Nerve Stimulator
Vagus nerve stimulation is an experimental technique for controlling seizures in patients for whom drugs and surgery have been ineffective (69,70). A vagus nerve stimulator consists of a small electrode, which is implanted around the left vagus nerve in the left side of the neck (Fig 32). The electrode is connected to a programmable generator, which is placed under the skin in the upper left side of the chest. Left vagus nerve stimulation is thought to have little effect on the heart, whereas right vagus nerve stimulation produces more cardiac effect. Experimental work has shown that stimulating the vagus nerve innervates a number of organs, including the heart, lungs, larynx, vocal cord, stomach, tongue, and ears, and it sends sensory signals into the brain stem. For unknown reasons, such stimulation may control seizures, and it has also been shown experimentally to be successful in treating depression.

View larger version (121K): [in this window] [in a new window] [Download PPT slide]   Figure 32a.  Vagus nerve stimulator. Frontal (a) and lateral (b) radiographs of the neck show a left vagus nerve stimulator used to treat intractable epilepsy.

View larger version (121K): [in this window] [in a new window] [Download PPT slide]   Figure 32b.  Vagus nerve stimulator. Frontal (a) and lateral (b) radiographs of the neck show a left vagus nerve stimulator used to treat intractable epilepsy.

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 33.  Frontal radiograph of a 45-year-old woman with pseudotumor cerebri shows two "lumboperitoneal" shunts in place. The inferior shunt tip overlies the L-4 to L-5 level (bottom arrowheads). The superior shunt (top arrowheads) is seen here; its tip goes into the thoracic region and is not pictured on this view of the lumbar spine.

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 34.  Lateral radiograph of the neck shows an esophageal temperature probe. There is also a probable pulse oximeter probe on one of the earlobes, an endotracheal tube, and an anterior cervical fixation plate.

	Footnotes

 
Editor’s Note.— Material from this article (including Figs 7, 10a, 10c, 10d, 12, 14, 16, 17, 19a, 19b, 21, 23, 30a—30c, 31c, and 31d) was adapted from material originally published in Radiologic Guide to Medical Devices and Foreign Bodies, edited by Tim B. Hunter and D. G. Bragg, St Louis, Mo, Mosby–Year Book, 1994. Permission for use of this material was granted by Tim B. Hunter, copyright holder.

Abbreviations: CSF = cerebrospinal fluid, DCS = dorsal column stimulator, TENS = transcutaneous electrical neural stimulation

	References

Top Abstract Introduction Brain and Skull Cervical Spine Thoracic and Lumbar Spine Mandible and Maxilla: Dental... Neck References

 

1. Pudenz RH. The surgical treatment of hydrocephalus: an historical review. Surg Neurol 1981; 15:15-26.[CrossRef][Medline]
2. Portnoy HD, Schulte RR, Fox JL, Croissant PD, Tripp L. Antisiphon and reversible occlusion valve for shunting in hydrocephalus and preventing post-shunt subdural hematomas. J Neurosurg 1973; 38:729-738.[Medline]
3. Goeser CD, McLeary MS, Young LW. Diagnostic imaging of ventriculoperitoneal shunt malfunctions and complications. RadioGraphics 1998; 18:635-651.[Abstract]
4. Zemack G, Romner B. Seven years of clinical experience with the programmable Codman Hakim valve: a retrospective study of 583 patients. J Neurosurg 2000; 92:941-948.[Medline]
5. Black DW. Subdural hematoma. Postgrad Med 1985; 78:107-114.[CrossRef]
6. Camel M, Grubb RL. Treatment of chronic subdural hematoma by twist-drill craniotomy with continuous catheter drainage. J Neurosurg 1986; 65:183-187.[Medline]
7. Markwalder TM, Seiler RW. Chronic subdural hematomas: to drain or not to drain? Neurosurgery 1985; 16:185-188.[Medline]
8. Nakaguchi H, Tanishima T, Yoshimasu N. Relationship between drainage catheter location and postoperative recurrence of chronic subdural hematoma after burr-hole irrigation and closed-system drainage. J Neurosurg 2000; 93:791-795.[Medline]
9. Katariwala NM, Bakay RA, Pennell PB, Olson LD, Henry TR, Epstein CM. Remission of intractable partial epilepsy following implantation of intracranial electrodes. Neurology 2001; 57:1505-1507.[Abstract/Free Full Text]
10. Matsunaga K, Akamatsu N, Uozumi T, Urasaki E, Tsuji S. Early and late inhibition in the human motor cortex studied by paired stimulation through subdural electrodes. Clin Neurophysiol 2002; 113:1099-1109.[CrossRef][Medline]
11. Saint-Cyr JA, Hoque T, Pereira LC, et al. Localization of clinically effective stimulating electrodes in the human subthalamic nucleus on magnetic resonance imaging. J Neurosurg 2002; 97:1152-1166.[Medline]
12. Yang PJ, Halbach VV, Higashida RT, Hieshima GB. Platinum wire, a new transvascular embolic agent. AJNR Am J Neuroradiol 1988; 9:547-550.[Abstract]
13. Jansen O, Dorfler A, Forsting M, et al. Endovascular therapy of arteriovenous fistulae with electrolytically detachable coils. Neuroradiology 1999; 41:951-957.[CrossRef][Medline]
14. Hemphill JC, 3rd, Gress DR, Halbach VV. Endovascular therapy of traumatic injuries of the intracranial cerebral arteries. Crit Care Clin 1999; 15:811-829.[CrossRef][Medline]
15. Matsumaru Y, Hyodo A, Nose T, Hirano T, Ohashi S. Embolic materials for endovascular treatment of cerebral lesions. J Biomater Sci Polym Ed 1997; 8:555-569.[Medline]
16. Yasargil MG, Vise WM, Bader DC. Technical adjuncts in neurosurgery. Surg Neurol 1977; 8:331-336.[Medline]
17. Dempsey JF, Williams JA, Stubbs JB, Patrick TJ, Williamson JF. Dosimetric properties of a novel brachytherapy balloon applicator for the treatment of malignant brain-tumor resection-cavity margins. Int J Radiat Oncol Biol Phys 1998; 42:421-429.[CrossRef][Medline]
18. Hammoud DA, Belden CJ, Ho AC, Dal Pan J, Herskovits EH, et al. The surgical bed after BCNU polymer wafer placement for recurrent glioma: serial assessment on CT and MR imaging. AJR Am J Roentgenol 2003; 180:1469-1475.[Abstract/Free Full Text]
19. Corcoran AL. A very basic introduction to hearing aids. Int Rehabil Med 1983; 5:79-81.[Medline]
20. Berliner KI, House WF. The cochlear implant program: an overview. Ann Otol Rhinol Laryngol Suppl 1982; 91:11-14.[Medline]
21. Witte RJ, Lane JI, Driscoll CLW, Lundy LB, Bernstein MA, Kotsenas AL, Kocharian A. Pediatric and adult cochlear implantation. RadioGraphics 2003; 23:1185-1200.[Abstract/Free Full Text]
22. Gates GA, Miyamoto RT. Cochlear implants. N Engl J Med 2003; 349:421-423.[Free Full Text]
23. Hodges AV, Balkany TJ. Cochlear implants for sensorineural hearing loss. Hosp Phys 2002; 38:22-28.
24. Stone JA, Mukherji SK, Jewett BS, Carrasco VN, Castillo M. CT evaluation of prosthetic ossicular reconstruction procedures: what the otologist needs to know. RadioGraphics 2000; 20:593-605.[Abstract/Free Full Text]
25. Stringfellow GJ, Francis IC. Images in clinical medicine: appearance of intraocular silicone oil on computed tomography. N Engl J Med 2003; 348:1122.[Free Full Text]
26. Ko G, Song H, Seo T, Sung K, Yoon H. Obstruction of the lacrimal system: treatment with a covered, retrievable, expandable nitinol stent versus a lacrimal polyurethane stent. Radiology 2003; 227:270-276.[Abstract/Free Full Text]
27. Bohler J, Gaudernak T. Anterior plate stabilization for fracture-dislocation of lower cervical spine. J Trauma 1980; 20:203-205.[Medline]
28. Crockard HA, Ransford AO. Stabilization of the spine. Adv Tech Stand Neurosurg 1990; 17:159-188.[Medline]
29. Gore DR, Gardner GM, Sepic SB, Murray MP. Roentgenographic findings following anterior cervical fusion. Skeletal Radiol 1986; 15:556-559.[CrossRef][Medline]
30. Larson SJ, Sances A, Cusic JF, Meyer GA, Swiontek T. A comparison between anterior and posterior spinal implant systems. Surg Neurol 1975; 4:180-186.[Medline]
31. de Oliveira JC. Anterior plate fixation of traumatic lesions of the lower cervical spine. Spine 1987; 12:324-329.[CrossRef][Medline]
32. Cooper PR, Cohen A, Rosiello A, Coslow M. Posterior stabilization of cervical spine fractures and subluxations using plates and screws. Neurosurgery 1988; 23:300-306.[Medline]
33. Churney WB, Sonntag VK, Douglas RA. Lateral mass posterior plating and facet fusion for cervical spine instability. BNI Q 1991; 7:2-11.
34. Lesoin F, Viaud C, Jomin M. Universal plate for anterior cervical spine osteosynthesis. Acta Neurochir (Wien) 1985; 77:60-61.[CrossRef][Medline]
35. Stauffer ES. Wiring techniques of the posterior cervical spine for the treatment of trauma. Orthopedics 1988; 11:1543-1548.[Medline]
36. Tippets RH, Apfelbaum RI. Anterior cervical fusion with the Caspar instrumentation system. Neurosurgery 1988; 22:1008-1013.[Medline]
37. Johnson RM, Owen JR, Hart DL, Callahan RA. Cervical orthoses. Clin Orthop 1981; 154:34-45.
38. Esses SI, Bednar DA. Screw fixation of odontoid fractures and nonunions. Spine 1991; 16:S483-S485.[Medline]
39. Bucholz RD, Cheung KC. Halo vest versus spinal fusion for cervical injury: evidence from an outcome study. J Neurosurg 1989; 70:884-892.[Medline]
40. Kostuik JP. Indications for use of the halo immobilization. Clin Orthop 1981; 154:46-50.
41. Whitehill R, Richman JA, Glaser JA. Failure of immobilization of the cervical spine by halo vest. J Bone Joint Surg Am 1986; 68:326-332.[Abstract/Free Full Text]
42. Cotrel Y, Dubousset J, Guillaumat M. New universal instrumentation in spinal surgery. Clin Orthop 1988; 227:10-23.[Medline]
43. Drummond DS. Harrington instrumentation with spinous process wiring for idiopathic scoliosis. Orthop Clin North Am 1988; 19:281-289.[Medline]
44. Egnatchik JG. Lumbar spine stabilization: techniques. Clin Neurosurg 1990; 36:159-167.[Medline]
45. Luque ER. Interpeduncular segmental fixation. Clin Orthop 1986; 203:54-57.
46. Selby D. The Knodt Rad. White AH, Rothman RH, Ray CD, eds. Lumbar spine surgery. St Louis, Mo: Mosby, 1982.
47. Steffee AD, Biscup RS, Sitkowski DJ. Segmental spine plates with pedicle screw fixation. Clin Orthop 1986; 203:45-53.
48. Lee CK, Langrana NA, Parsons JR, Zimmerman MC. Development of a prosthetic intervertebral disc. Spine 1991; 16:S253-S255.[CrossRef][Medline]
49. Hu SS, Pashman RS. Spinal instrumentation: evolution and state of the art. Invest Radiol 1992; 27:632-647.[CrossRef][Medline]
50. Slone RM, MacMillan M, Montgomery WJ. Spinal fixation. Part 1. Principles, basic hardware, and fixation techniques for the cervical spine. RadioGraphics 1993; 13:341-356.
51. Slone RM, MacMillan M, Montgomery WJ, Heare M. Spinal fixation. Part 2. Fixation techniques and hardware for the thoracic and lumbosacral spine. RadioGraphics 1993; 13:521-543.
52. Slone RM, MacMillan M, Montgomery WJ. Spinal fixation. Part 3. Complications of spinal instrumentation. RadioGraphics 1993; 13:797-816.
53. Aebi M, Thalgott JS, Webb JK. AO ASIF principles in spine surgery Berlin, Germany: Springer, 1998.
54. An HS, Cotler JM, eds. Spinal instrumentation 2nd ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 1999.
55. Benzel EC. Spine surgery Vols 1, 2. Philadelphia, Pa: Churchill Livingstone, 1999.
56. Hitchon PW, Traynelis VC, Rengachary S. Techniques in spinal fusion and stabilization New York, NY: Thieme Medical Publishers, 1995.
57. Cotten A, Boutry N, Cortet B, et al. Percutaneous vertebroplasty: state of the art. RadioGraphics 1998; 18:311-323.[Abstract]
58. Burton C. Dorsal column stimulation, optimization of application. Surg Neurol 1975; 4:171-179.[Medline]
59. Campos RJ, Dimitrijevic MR, Sharkey PC, Sherwood AM. Epidural spinal cord stimulation in spastic spinal cord injury patients. Appl Neurophysiol 1987; 50:453-454.[Medline]
60. Mundinger F, Neumuller H. Programmed stimulation for control of chronic pain and motor diseases. Appl Neurophysiol 1982; 45:102-111.[Medline]
61. Ray CD. Electrical and chemical stimulation of the CNS by direct means for pain control: present and future. Clin Neurosurg 1981; 28:564-588.[Medline]
62. Richardson RR, Siqueira EB, Cerullo LJ. Spinal epidural neuro stimulation for treatment of acute and chronic intractable pain: initial and long term results. Neurosurgery 1979; 5:344-348.[Medline]
63. van Kerrebroeck PE. The role of electrical stimulation in voiding dysfunction. Eur Urol 1998; 34:27-30.
64. Phillips R. Skinner’s science of dental materials 9th ed. Philadelphia, Pa: Saunders, 1991.
65. Stafne E. Stafne’s oral radiographic diagnosis 5th ed. Philadelphia, Pa: Saunders, 1985.
66. Price DB. Tubes in the alimentary and respiratory tracks: appearances on CT scans of the head and neck. AJR Am J Roentgenol 1991; 156:1047- 1051.[Free Full Text]
67. Stoelting RK. Endotracheal intubation In: Miller RD, ed. Anesthesia. 2nd ed. New York: Churchill-Livingstone, 1986.
68. Hunter TB, Taljanovic MS. Overview of medical devices. Curr Probl Diagn Radiol 2001; 30:94-139.[CrossRef][Medline]
69. Morris GL, Mueller WM. Long term treatment with vagus nerve stimulation in patients with refractory epilepsy. The Vagus Nerve Stimulation Study Group E01–E05. Neurology 1999; 53:1731-1735.
70. Rosenbaum JF, Heninger G. Vagus nerve stimulation for treatment-resistant depression. Biol Psychiatry 2000; 47:273-275.[CrossRef][Medline]
71. Li V. Methods and complications in surgical cerebrospinal fluid shunting. Neurosurg Clin N Am 2001; 12:685-693.[Medline]
72. Burgett RA, Purvin VA, Kawasaki A. Lumboperitoneal shunting for pseudotumor cerebri. Neurology 1997; 49:734-739.[Abstract/Free Full Text]
73. Vicenzi MN, Gombotz H, Krenn H, Dorn C, Rehak P. Transesophageal versus surface pulse oximetry in intensive care unit patients. Crit Care Med 2000; 28:2268-2270.[CrossRef][Medline]
74. Mekjavic IB, Rempel ME. Determination of esophageal probe insertion length based on standing and sitting height. J Appl Physiol 1990; 69:376-379.[Abstract/Free Full Text]
75. Robinson J, Charlton J, Seal R, Spady D, Joffres MR. Oesophageal, rectal, axillary, tympanic and pulmonary artery temperatures during cardiac surgery. Can J Anaesth 1998; 45:317-323.[Medline]

This article has been cited by other articles:

				E. E. Rutherford, L. J. Tarplett, E. M. Davies, J. M. Harley, and L. J. King Lumbar Spine Fusion and Stabilization: Hardware, Techniques, and Imaging Appearances RadioGraphics, November 1, 2007; 27(6): 1737 - 1749. [Abstract] [Full Text] [PDF]

				M. S. Taljanovic, T. B. Hunter, M. J. O'Brien, and S. A. Schwartz Gallery of Medical Devices: Part 2: Devices of the Head, Neck, Spine, Chest, and Abdomen RadioGraphics, July 1, 2005; 25(4): 1119 - 1132. [Abstract] [Full Text] [PDF]

				T. B. Hunter and M. S. Taljanovic Medical Devices of the Abdomen and Pelvis RadioGraphics, March 1, 2005; 25(2): 503 - 523. [Abstract] [Full Text] [PDF]

				T. B. Hunter, M. S. Taljanovic, P. H. Tsau, W. G. Berger, and J. R. Standen Medical Devices of the Chest RadioGraphics, November 1, 2004; 24(6): 1725 - 1746. [Abstract] [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) Erratum (v24,p418) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hunter, T. B. Articles by Berger, W. G. Search for Related Content PubMed PubMed Citation Articles by Hunter, T. B. Articles by Berger, W. G. Related Collections Musculoskeletal Radiology Neuroradiology