(Radiographics. 1999;19:1385-1387.)
© RSNA, 1999
Cases of the Day 1
US Case of the Day
Ashley F. Ceola, MD and
Teresita L. Angtuaco, MD
1 From the Department of Radiology, University of Arkansas for Medical Sciences, 4301 W Markham, Little Rock, AK 72205. From the 1998 RSNA scientific assembly. Received November 20, 1998; revision requested January 15, 1999 and received February 3; accepted February 4. Address reprint requests to T.L.A..
Index Terms: Brain, abnormalities, 10.2066 • Brain, calcification, 10.81 • Brain, infection, 10.2066 • Cytomegalovirus, 10.2066 • Fetus, central nervous system, 856.81 • Infants, newborn, central nervous system, 10.81
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HISTORY
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A 17-year-old primigravida girl was referred to our institution because microcephaly was suspected on the basis of results of initial ultrasonography (US) performed at her obstetrician's office. Although there was no reliable menstrual history for correlation, the pregnancy was estimated to be at term on the basis of earlier US findings obtained at a different institution. The course of pregnancy was uneventful, and the patient was asymptomatic at the time of presentation. Obstetric US was performed.
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FINDINGS
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The reliability of obstetric US findings was compromised by the low position of the fetal head in the pelvis. The patient refused endovaginal US for better evaluation of the fetal head. Despite suboptimal visualization, axial US images of the fetal head suggested multiple intracranial calcifications and ventriculomegaly (Fig 1a). Fetal abdominal US demonstrated hepatosplenomegaly (Fig 1b). No intraabdominal calcifications were detected. Results of fetal biometry suggested microcephaly by demonstrating a marked discrepancy between the head and femur measurements. The abdominal circumference was also disproportionately large, but this was believed to be due to organomegaly. After delivery, US of the neonatal head was performed through a limited transcranial window. The resulting images showed diffuse calcifications in the brain parenchyma and subependymal regions (Fig 2). Computed tomography (CT) of the head (Fig 3) showed even more extensive intracranial calcifications than did US, thereby helping confirm the US findings.
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Figure 1a. (a) Axial US image of the fetal head shows brightly echogenic intracerebral calcifications near the base of the skull (arrow) despite limited visualization of the head itself. (b) Transverse US image of the fetal abdomen shows a markedly enlarged liver (arrow) and spleen (arrowhead) nearly equal in size occupying the abdomen. The stomach, which is usually seen at this level, is not visualized and is probably compressed by the organomegaly.
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Figure 1b. (a) Axial US image of the fetal head shows brightly echogenic intracerebral calcifications near the base of the skull (arrow) despite limited visualization of the head itself. (b) Transverse US image of the fetal abdomen shows a markedly enlarged liver (arrow) and spleen (arrowhead) nearly equal in size occupying the abdomen. The stomach, which is usually seen at this level, is not visualized and is probably compressed by the organomegaly.
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Figure 2a. (a) Coronal US image of the neonatal head obtained at the level of the occipital horns of the lateral ventricles shows extensive subependymal calcifications (arrow). (b) Right parasagittal US image of the head shows severe calcification of the basal ganglia (arrow).
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Figure 2b. (a) Coronal US image of the neonatal head obtained at the level of the occipital horns of the lateral ventricles shows extensive subependymal calcifications (arrow). (b) Right parasagittal US image of the head shows severe calcification of the basal ganglia (arrow).
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Figure 3. Head CT scan demonstrates diffuse calcifications in the basal ganglia and subependymal regions of the brain. The degree of involvement is more extensive than was suspected at US.
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DIAGNOSIS: Congenital cytomegalovirus infection.
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DISCUSSION
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Cytomegalovirus is a double-stranded DNA virus that is a member of the Herpesviridae family. Like other herpes viruses, cytomegalovirus undergoes periods of reactivation despite the presence of serum antibodies. The virus is usually asymptomatic except in immunosuppressed patients. However, up to 15% of healthy adults experience symptoms including fever, pharyngitis, lymphadenopathy, and polyarthritis (1). The virus is transmitted horizontally by means of contact with saliva and urine and vertically from mother to fetus, usually transplacentally. Cytomegalovirus can also be transmitted sexually. Immunocompromised states drastically increase the risk of serious infection.
Cytomegalovirus is the most common cause of perinatal infection, occurring in 0.5%–2.4% of all live births (2). It is the leading cause of brain disease and hearing loss in children. Primary maternal infection increases the chance of severe morbidity, especially in the first half of pregnancy. However, most infections result from virus reactivation and are less likely to have clinical sequelae. It is estimated that 40,000 babies are born each year with cytomegalovirus infection, only 10% of whom are symptomatic (3). Diagnosis of congenital infection requires a positive viral culture from the neonate within the first 2 weeks of life.
Intracranial calcifications are the most common abnormality and are strongly associated with mental retardation (3). These calcifications occur in regions of cell necrosis and are usually deposited just beneath the ependyma of the lateral ventricles. Calcification may also be seen throughout the brain parenchyma simulating that seen in toxoplasmosis. Toxoplasmosis is the most common cause of intracerebral calcification in neonates with calcifications that have the tendency to spread throughout the brain. Toxoplasmosis is most commonly seen in the posterior aspect of the brain with curvilinear calcifications in the thalamus and basal ganglia (4). Intracerebral calcifications occur late in pregnancy and can be seen at prenatal US. Other causes of calcification include teratoma, tuberous sclerosis, Sturge-Weber syndrome, and venous sinus thrombosis.
Central nervous system sequelae from cytomegalovirus include white matter abnormalities, ventricular dilatation, cerebellar hypoplasia, microcephaly, cortical atrophy, and hydrocephalus. Hydrocephalus may be communicating or obstructive secondary to obliterative arachnoiditis (5). Ocular abnormalities occur in 15%–50% of symptomatic neonates (2), most commonly chorioretinitis, optic atrophy, optic nerve hypoplasia, and unilateral colobomas. Other ocular abnormalities include microphthalmia, anterior uveitis, cataracts, and anophthalmia.
Nontender hepatosplenomegaly is a common finding in the abdomen and can be detected with prenatal US (as in this case). Differential diagnosis of fetal hepatomegaly includes congenital infections, severe hemolytic disease, Beckwith-Wiedemann syndrome, and Zellweger syndrome. Other features of the cytomegalovirus syndrome are low birth weight, mental and motor retardation, sensorineural deficits, jaundice, hemolytic anemia, and thrombocytic purpura (6).
No effective treatment exists for maternal infection. Maternal immunity does not protect against congenital infection because of the possibility of viral reactivation after a latent period. Risk factors for severe infection include primary infection any time during pregnancy and nonprimary infection during the first half of pregnancy. Most neonates who shed cytomegalovirus after birth are asymptomatic. Those with abnormal imaging findings are at high risk for adverse neurologic and developmental outcomes (7). In this case, the neonate died 22 days after birth.
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References
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Cunningham FG, MacDonald PC, Gant NF. Williams obstetrics Norwalk, Conn: Appleton & Lange, 1989; 1287-1288.
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Sekhsaria S, Rahbar F, Fomufod A, Mason R, Kosoko O, Trouth J. An unusual case of congenital cytomegalovirus infection with glaucoma and communicating hydrocephalus. Clin Pediatr 1992; 31:505-507.
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Boppana SB, Fowler KB, Vaid Y, Hedlund G, Britt WJ, Pass RF. Neuroradiographic findings in the newborn period and long-term outcome in children with symptomatic congenital cytomegalovirus infection. Pediatrics 1997; 99:409-414.[Abstract/Free Full Text]
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Roach ES, Sumner TE, Volberg FM, Boyle RJ, Young LW. Radiologic case of the month: intracranial calcifications with cytomegalovirus. Am J Dis Child 1983; 137:799-800.[Medline]
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Twickler DM, Perlman J, Maberry MC. Congenital cytomegalovirus infection presenting as cerebral ventriculomegaly on antenatal sonography. Am J Perinatol 1993; 10:404-406.[Medline]
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Bale JF, Blackman JA, Sato Y. Outcome in children with symptomatic congenital cytomegalovirus infection. J Child Neurol 1990; 5:131-136.[Abstract/Free Full Text]
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Hayward JC, Titelbaum DS, Clancy RR, Zimmerman RA. Lissencephaly-pachygyria associated with congenital cytomegalovirus infection. J Child Neurol 1991; 6:109-114.[Abstract/Free Full Text]
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HISTORY
FINDINGS
