[Intracranial arachnoid cysts. A study of a series of 35 cases]

Arachnoid cysts are cavities with a content similar to cerebrospinal fluid, frequently communicating with the subarachnoid space. They make up 1% of the intracranial space occupying lesions, and although typically seen in children (13%), they may be undiagnosed until the patient has become adult.

We review a series of 35 cases of congenital intracranial arachnoid cysts in children, which had been investigated in the Neuropaediatric Department during 1987 1999. The patients had had cranial CAT and MR, and transcranial echography studies.

In 85.7% there was a single cyst. The Sylvan fissure and posterior fossa were the commonest sites. The age of diagnosis was under 1 year in 54.3% and at birth in 25.7%. There were other associated malformations of the central nervous system in 31.4%, with agenesis of the corpus callosum in 45.5%. The most frequent clinical features on presentation of the condition were macrocephaly (31.4%) and epileptic crises (25.7%). The surgical treatment most often used was cystoperitoneal shunt.

Congenital arachnoid cysts are caused by alteration in the embryogenesis of the central nervous system, and hence their association with other malformations and prevalence in children. The most frequent clinical findings were macrocephaly, due to the size of the cyst or the associated hydrocephaly, and epileptic seizures secondary to cortical irritation caused by pressure. Management of symptomatic lesions is surgical. The cystoperitoneal shunt was generally used in our series, since this was followed by clinical improvement in most cases.