Cranial CT findings in patients with meningomyelocele.

The association between meningomyelocele and various cranial abnormalities, particularly Chiari II malformation is well established. Cranial CT scans in 47 patients with meningomyelocele proved to be a safe and effective method of elucidating the type and extent of anatomic abnormalities associated with this disorder, and evaluating and following the degree of hydrocephalus seen in these patients. Of the 47 patients, 43 (92%) showed CT findings indicative of an abnormally low fourth ventricle, the hallmark finding in Chiari II malformation. In 67% the fourth ventricle was not visualized, and in 25% it was directly visualized in an abnormally caudal position. Other findings included hydrocephalus (85%), a striking and possibly unique heart-shaped psuedomass in the posterior fossa (58%), and abnormal configuration of the lateral ventricles ("vampire bat" configuration). Calvarial abnormalities, in particular lacunar skull, were also noted at CT.