Pseudohydrocephalus-megalocephaly, increased intracranial pressure and widened subarachnoid space.

Seven children with rapid enlargement of the head and other clinical features resembling hydrocephalus are described. All children remained with relatively large heads, developed slowly and all but one had various degrees of mental and motor handicaps. The EEG was disturbed in all cases; two children developed seizures. Increased intracranial pressure was present. In all patients the subarachnoid space was markedly widened while the ventricular system was normal or minimally dilated. The characteristics of this syndrome, the features distinguishing it from similar conditions as well as its possible mechanism are discussed.