Infantile chronic subdural hematoma of the posterior fossa diagnosed by computerized tomography. Case report.

A 9-week-old infant manifested continuous vomiting for 1 week accompanied by a tense fontanel, "sun setting" of the eyes, frequent opisthotonos, and hypertonicity. The head circumference was at the 50th percentile. Computerized tomography (CT) revealed acute hydrocephalus and a posterior fossa subdural hematoma. The brain stem and cerebellum were of greater density (54 Hounsfield units) than normal cerebral white matter (42 Hounsfield units) whereas the subdural hematoma was the same density as normal cerebral white matter ("isodense"). The cerebellum and brain stem became enhanced by contrast (68 Hounsfield units), but no enhancement occurred in the cerebral white matter or subdural hematoma. A shunt followed by occipital craniectomy resolved both the hydrocephalus and subdural hematoma. Repeat CT scan 15 days postoperatively disclosed continuing higher density of the cerebellum and brain stem (60 Hounsfield units) relative to cerebral white matter. Increased density of the infantile cerebellum has been noted previously but not to the same extent as in this patient.