Cerebral cysticercosis. We studied 143 cases of cerebral cysticercosis over a 30-year period. In 46 there was hydrocephalus due to cysts obstructing the cerebrospinal fluid pathways, with signs of hydrocephalus and cerebellar dysfunction. In 97 there were cysts in the cerebral parenchyma, causing symptoms of intracranial hypertension alone in 22 cases, with additional neurological deficits in the remainder. Before 1980 diagnosis was made by pneumoencephalography and ventriculography, but since then it has mostly been done by computed tomography. In 28 cases scanned, typical abnormalities were present in 25. Complement fixation tests were positive in serum in 74% of cases and in cerebrospinal fluid in 73%, and the enzyme-linked immunosorbent assay test was positive in serum in 90% and in cerebrospinal fluid in 92%. Treatment of cases with hydrocephalus was by removal of the cysts at craniotomy, with placement of a shunt where necessary. Intracranial hypertension caused by parenchymal cysts was treated with steroids and osmotic agents, if possible. In resistant cases subtemporal decompression was needed, unilateral in 55 cases and bilateral in eight. Mortality in the acute stage was 11%, with a further 20% at follow up. 