A simple method of assessing intracranial pressure in hydrocephalic patients with shunts

A simple method is described for assessing intracranial pressure in patients with Holter valves when the function is questionable. The method entails measuring intravalvular pressure by puncturing the valve belly with a fine needle connected to a manometer. High pressure suggests a distal occlusion; very low pressure coupled with difficulty in aspirating CSF suggests a proximal occlusion. All pressures have to be corrected by the addition of a factor equal to half the pressure specification of the valve. The results of a pilot study support these conclusions.