[Agenesis of the corpus callosum associated with interhemispheric cyst. A case report].

A 7-year-old boy was admitted because of convulsive seizures. He was diagnosed as agenesis of corpus callosum associated with interhemispheric cyst by CT scan and angiography. Metrizamide CT cisternography and cystography disclosed no communication between interhemispheric cyst and the third ventricle. By means of metrizamide CT cisternography and cystography, the authors considered this interhemispheric cyst gradually increased by some kinds of ball-valve mechanism. Cysto-peritoneal shunt was carried out. Postoperative course was uneventful and follow-up CT revealed disappearance of interhemispheric cyst and typical findings of the acallosal brain. Improvement of clinical symptoms and EEG findings occurred after operation. Agenesis of the corpus callosum associated with interhemispheric cyst is rare. The authors can find only one case of this brain anomaly in the literature in which there is no communication between interhemispheric cyst and the third ventricle. Metrizamide CT cisternography and cystography was very useful in diagnosis and selection of treatment.