Outcome in children with space-occupying posterior fossa arachnoid cysts.

While prognostic information for Dandy-Walker syndrome and non-progressive cerebellar ataxia/cerebellar hypoplasia is available, surprisingly scant literature reports are found for space-occupying posterior fossa arachnoid cysts (PFAC). We describe the outcome of patients with symptomatic PFAC shunted as infants. Only 11 children were seen over a 20-year period (1980-1999). Cyst location was retrocerebellar (n = 8), supravermian (n = 2) and in the cerebellopontine angle (n = 1). Motor and cognitive impairments in one child were interpreted as the result of neurosurgical complications (intraventricular and intracerebral haemorrhage). One 6-year-old boy had mild truncal ataxia and mild cognitive delay. The 9 other patients had no evidence of ataxia or clumsiness and had average, some even above average, cognitive ability and scholastic achievements. Epilepsy was not a feature. We conclude that the prognosis of PFAC for cognitive development and neurological signs is favourable.