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Letters to the Editor |
Department of Diagnostic Radiology, National Institutes of Health/Clinical Center, 10 Center Drive, Rm 1C 660, Bethesda, MD 20892-1182. e-mail: zneeman@cc.nih.gov
Department of Radiology, Hadassah University Hospital, Jerusalem, Israel
Editor: The article by Lustrin et al, "Pediatric Cervical Spine: Normal Anatomy, Variants, and Trauma" in the May-June 2003 issue of RadioGraphics (1) is an important and comprehensive review of the pediatric cervical spine. However, the authors have inaccurately reported the true prevalence of occipital condyle fractures (OCF) caused by high-energy blunt trauma to the craniocervical junction in the pediatric and young adult population: "... Fractures of the occipital condyles are extremely rare ..." Underestimating the prevalence of this entity may lead to an incomplete overall understanding of its importance by the reader, possibly resulting in a detrimental clinical outcome because of missed diagnosis. We would like to take this opportunity to provide a brief description of OCF, including its prevalence, classification, clinical findings, and mechanism of injury, that should prompt immediate evaluation with computed tomography (CT) and magnetic resonance (MR) imaging in pediatric victims of high-energy blunt trauma.
A recent search of the literature of OCF in both the pediatric and adult populations revealed 15 and 100 cases, respectively (2). On the basis of these numbers, one might conclude that OCF is extremely rare following blunt high-energy trauma to the craniocervical junction.
Since OCF was first described by Bell in 1817 (3), there had been only a handful of descriptions of this entity in adults, with no documentation in the pediatric or young adult population. However, in the past 2 decades, reporting of OCF has been increasing, probably related to widespread use of CT and MR imaging and greater awareness of this entity. The true prevalence of OCF is unknown, but most authors have concluded that OCF is probably more common than realized (4,5). The reported incidence of OCF in prospective studies ranges from 4% (6) to 16.4% (7) and even to 19% (8). The numbers vary greatly for a number of reasons: inclusion criteria, awareness, appropriate thin-section CT of the craniocervical junction, and use of sagittal and coronal reformatted images. The authors of a recent article in Pediatric Neurosurgery who reviewed all reported pediatric cases in the literature concluded that, although OCFs are less frequent in children than in adults, they are not as rare in children as previously thought (2).
A retrospective radiologic review of OCF in 95 adult and pediatric patients by Hanson et al (9) demonstrated that lateral cervical spine radiography has a limited role in the detection of OCF and that craniocervical CT can be readily performed and provides a basis for OCF characterization and treatment planning. The authors estimated that OCF occurs in approximately one to two of 1,000 seriously injured patients (injury severity score >8). In the United States in 2000, nearly 330,000 children were injured as occupants in motor vehicles (10), and in 1998, 30,000 children were injured as pedestrians (11). A recent review of the U.S. pediatric trauma registry database for mortality and functional outcome with and without head injuries reported 15,000 pediatric patients with head injuries (12). Given these staggering numbers, one cannot overlook the significant number of pediatric patients who may have concurrent OCF involvement.
The most common classification of OCF is based on a report by Anderson and Montesano in 1988 (13). They described a series of six patients, including two under the age of 21 years, and defined three fracture types with associated ligament injury (13). Type 1 is an impacted comminuted fracture, without significant displacement of the fragments in the foramen magnum and with ipsilateral alar ligament injury involvement. A type 1 fracture is considered stable because of an intact contralateral alar ligament and tectorial membrane. The mechanism of injury is a primarily axial force. Type 2 is a skull base fracture extending to and involving the occipital condyle, and it is not associated with internal craniocervical joint ligament injury. It is considered stable unless the line of fracture completely separates the occipital condyle from the occiput. The mechanism of injury is a direct blow to the cranium. Type 3 is a potentially unstable, ipsilateral avulsion fracture of the occipital condyle by the alar ligament. The condylar fragment is free and may be displaced into the foramen magnum toward the odontoid process. The mechanism of injury involves a combination of lateral inclination and rotation. A type 3 fracture is considered unstable.
A more recent classification by Tuli et al (14) is based on the demonstration of instability of the C0-C1-C2 complex. This demonstration may include the presence of a displaced condyle fragment associated with radiologic evidence of instability (radiographic or CT) or ligamentous disruption (MR imaging). Type 1 is a nondisplaced fracture and is considered stable. Type 2 is a displaced fracture with no MR imaging evidence of craniocervical ligamentous disruption, and it is considered stable. Type 3 is a displaced fracture with instability of C0-C1-C2 or MR imaging evidence of craniocervical ligamentous disruption, and it is considered unstable.
The associated spectrum of clinical presentations is nonspecific, ranging from fatal atlanto-occipital dissociation to loss of consciousness, impaired consciousness, or pain and limitation of movement. At times, significant intracranial injury or acute lower cranial nerve deficit is associated. Patients may present with loss of or impaired consciousness. On the other hand, patients may be neurologically intact with a normal Glasgow coma scale. Bloom et al (7) reported that in all four pediatric patients with OCFs, physical signs were unreliable, secondary to either diminished level of consciousness or cervical spine fractures.
Most authors agree with the management of OCF proposed by Anderson, based on his classification (15). A hard collar or a cervicothoracic brace is used for stable types 1 and 2 OCFs. A halo vest is indicated for unstable types 2 and 3 OCFs. These management guidelines may lead to a good functional recovery. Surgical decompression and stabilization have been reported in only one adult patient. All 15 pediatric patients mentioned previously (2) were treated according to these guidelines, and no surgical intervention was indicated. Review of the pediatric OCF literature by Momjian et al (2) revealed that when OCF was appropriately treated, bone healing was good with no craniocervical pain or limitation of motion. However, if a neurologic deficit was present at the time of the OCF, there was persistence of long-term neurologic sequelae.
Therefore, in the context of high-energy blunt trauma to the craniocervicum in the injured child as well as in the adult, regardless of the Glasgow coma scale, one should not hesitate to include the C0–C2 junction during CT evaluation. It is imperative to obtain thin (1.5–2-mm) sections from the cranial base to the base of C2. This coverage facilitates adequate sagittal and coronal reformatted images that provide a clear depiction of OCF and craniocervical ligament injury (7). Familiarity with the normal secondary ossification centers of the occipital condyles and the dens is mandatory to avoid mistaking them for fractures. Early diagnosis of OCF should prompt immobilization of the cervical spine that may prevent delayed neurologic injuries and fatal brain stem compression.
References
Department of Radiology, Long Island Jewish Medical Center, 270–05 76th Ave, New Hyde Park, NY 11040
We thank Drs Neeman and Bloom for their thorough commentary regarding injuries to the craniocervical junction (1–3). We agree that the prevalence of these injuries is probably underestimated. As technology evolves and multidetector CT evaluation becomes more commonplace for cervical spine and head trauma, we agree that OCFs will be seen more frequently. The clinical ramifications related to the prompt diagnosis of such injuries, likewise, cannot be understated. Our comments about this specific type of injury are related to not only our experience with this type of injury but also to the limited number of published reports in the literature. Although the prevalence of these fractures is greater than previously reported, their frequency in children is still relatively low. We agree that the craniocervical junction should always be evaluated in all imaging studies of pediatric victims of cervical spine trauma.
References
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