Hippocampal Dysgenesis Associated With Temporal Lobe Hypoplasia and Arachnoid Cyst of the Middle Cranial Fossa

We describe two children with left hippocampal dysgenesis in association with temporal lobe hypoplasia and arachnoid cyst of the middle cranial fossa. The hippocampus showed an abnormal globular shape and blurred internal structure in both patients. One of the patients had juvenile myoclonic epilepsy without evidence of seizure onset in the abnormal temporal region. The other patient did not have epilepsy; however, he showed developmental language disorder with a probable relationship to the left temporal abnormalities. (J Child Neurol 2005;20:926—930).