Normal-Pressure Hydrocephalus

To the Editor.—  Several points in Dr. Panitch's letter are informative, interesting, and well taken. We would, however, like to answer several objections and clarify our position in this controversial area.Our primary purpose in this article was to emphasize the value of cerebrospinal fluid (CSF) imaging (cisternography) in the diagnosis of normal-pressure hydrocephalus. At the time of publication our experience included over 150 cisternograms, only eight of which unquestionably met the clinical, pneumoencephalographic, and laboratory findings generally accepted in the somewhat confusing entity of normal-pressure hydrocephalus. Of these eight patients, one died of a pulmonary embolus prior to a shunt, one died of a myocardial infarction shortly after a CSF diversionary shunt, four had marked improvement of neurological symptoms, one has had mechanical difficulties with the shunt, and one failed to improve.Continual reference to cisternography as "RISA cisternography" leads us to believe that the reader failed to grasp