Normal pressure hydrocephalus

Much remains to be learned about normal pressure hydrocephalus, but there is little doubt that it is a real entity and that a significant, although probably rather small, proportion of patients with progressive intellectual deterioration have dementia secondary to obstruction of CSF pathways and would benefit from ventricular decompression. Much of the evidence is fragmentary and incomplete; however, it appears that fibrosis and obliteration of the intracranial subarachnoid spaces and of the arachnoid granulations are a part of the normal aging process. This fibrosis may be accentuated by other processes, notably craniocerebral trauma, subarachnoid hemorrhage, meningitis, and probably other factors still unknown. Obliteration of the normal CSF pathways causes dilatation of the cerebral ventricles, producing various symptoms and signs, most notably progressive dementia. The clinical picture is quite variable, and neither the pneumoencephalogram nor the clinical findings have provided valid criteria. However, the scinticisternogram seems to be a relatively valid indicator of whether shunting will help a patient. To date, the results of shunting in patients with less severely abnormal scinticisternograms have been disappointing.