Normal-pressure hydrocephalus: diagnosis and patient selection for shunt surgery.

Currently accepted modes of clinical and radiologic evaluation were analyzed retrospectively in 55 patients with "normal-pressure" hydrocephalus on whom a cerebrospinal fluid shunting procedure was done. When applied alone, each criterion neither reliably differentiated normal-pressure hydrocephalus from cortical atrophy nor indicated in a significant number of cases which patients would benefit from shunting. Therefore, future prospective evaluations should include clinical history, physical and neurologic examination, skull radiography, echoencephalography, psychometric testing, brain scanning, lumbar puncture with cerebrospinal fluid laboratory analysis, isotope cisternography, pneumoencephalography, and constant-infusion manometric testing. Cerebral angiography may add optional support to the diagnosis of cortical atrophy but always should be done before lumbar puncture if there is evidence of intracranial mass and/or increased pressure is revealed on neurologic examination, skull radiographs, echograms, or brain scans. Patients with seizures should undergo electroencephalography. Postoperative improvement should be evaluated using serial neurologic and psychometric examinations. Echoencephalography may confirm postshunt reductions in ventricular size.