Abstract
Five patients suffering from dementia paralytica who failed to improve or deteriorated after one or several high dosage courses of penicillin, had pneumoencephalographic patterns suggesting communicating hydrocephalus. Measurements of the ventricular index, ratio of cella media to width of the temporal horn, and the callosal angle differed from that in seven cases of dementia paralytica with associated cerebral atrophy. An isotope cisternogram in three cases with communicating hydrocephalus further confirmed a blockage of the cerebrospinal fluid (CSF) at the parasagittal subarachnoid space. Three patients exhibited the full syndrome of gait apraxia, incontinence, and pyramidal tract signs associated with a severe degree of dementia. Shunting of the CSF in three cases was followed by immediate improvement in two, one in a longlasting way. No active parenchymal inflammation was observed in any of three brain biopsy samples taken during surgery, except for leptomeningeal fibrosis in one. Chronic leptomeningitis in dementia paralytica may impair subarachnoid CSF absorption with subsequent communicating hydrocephalus. Progression or inadequate responses after therapeutic dose of penicillin in dementia paralytica should prompt investigation for this complication as an alternative, effective treatment could be offered.