Background: Between 1993-1995, 51 patients under 75 years of age with clinical symptoms and CT-based diagnosis of normal pressure hydrocephalus were investigated prospectively in order to clarify the value of neuropsychological tests, clinical symptoms and signs and infusion test in the differential diagnosis and prediction of outcome in normal pressure hydrocephalus.
Methods: Patients had a thorough neurological examination, and neuropsychological evaluation. A 24-hour intraventricular ICP-measurement, infusion test, neurophysiological investigations and MRI study were performed, and a cortical biopsy was obtained. The ICP measurement defined the need for a shunt. All 51 patients were re-examined three and twelve months later. The final follow-up was accomplished five years postoperatively.
Findings: 25 of the patients needed a shunt operation. One year after a shunt placement 72% of these patients had a good recovery concerning activities of daily living, 58% benefited in their urinary incontinence and 57% walked better. During the 5 years of follow-up 8 patients with shunt and 9 without shunt had died. Positive effect of shunting remained. Only one neuropsychological test, recognition of words test, distinguishes the patients with the need for a shunt. Simple mini mental examination test was not different in those who improved. In the postoperative follow-up patients with shunt showed no change in neuropsychological tests even if they were subjectively better. The infusion test was of no value in diagnosing NPH. The 16 patients with Alzheimer's disease did worse after one year than those without pathological changes, but the mortality was not increased.
Interpretation: Specific neuropsychological tests are of little value in diagnosing NPH. Mini-Mental status examination was neither of value in diagnosing NPH nor in prediction of the outcome. In this study the infusion test did not improve diagnostic accuracy of NPH, but shunt placement relieves urinary incontinence and walking disability in patients with increased ICP. The patients with positive Alzheimer diagnosis on biopsy did not improve.