A prospective trial for diagnosis, treatment and evaluation of normal pressure 
hydrocephalus (NPH) was carried out in 30 consecutive patients (12 women, 18 
men, mean age: 61 years, range 21-80). The clinical diagnosis was based on the 
presence of one or more of the three clinical elements of NPH: gait disturbance, 
incontinence and mental deterioration as well as radiological criteria of 
ventricular enlargement. Preoperatively, physical and radiological 
investigations and psychological tests were routinely performed. Cognitive 
functions such as fluency, selective attention and motor speed were re-examined 
within 24 hours after spinal tap of 40-50 cc. of CSF. Results of shunting were 
confirmed by CT scans and evaluated by means of psychological tests at least 3 
months postoperatively. Psychological tests included IQ tests and tests for 
memory, selective attention and motor speed. Results indicate that spinal tap 
had no predictive value for the results after shunting as far as psychological 
functions are concerned. Shunt treatment showed an effect on cognitive functions 
of distractibility of attention and motor speed, but not on intelligence of 
memory. Three patients deteriorated, eleven remained stable and sixteen showed 
significant improvement on psychological tests, mainly those for attention, 
motor speed and memory, but rarely did any improvement of intelligence occur.