Cerebral arachnoid cyst: a lesion of the child's brain.

39 patients with 42 arachnoid cysts have been reviewed in a retrospective study. All kinds of arachnoid cysts reported in the literature were also found in this study. These consist mainly of congenital primary and post-traumatic secondary cysts. Cysts which cause no major neurological deficits require conservative treatment of symptoms only. Cysts which cause major symptoms because of their space occupying nature, however, require surgical treatment. Craniotomy with removal of membranes to allow free physiological circulation of CSF is the treatment of choice in our hands. Cysto-peritoneal shunting is an alternative procedure for patients in a poor condition. More than 50% (23 out of 39 cases) were younger then 20 years of age, suggesting that these cysts are mainly congenital lesions of the brain.