Malfunction of V-P Shunt System Equipped with Antisiphon Device in Normal-pressure Hydrocephalus

Three patients with normal-pressure hydrocephalus, who were treated by installation of a low-pressure ventriculo-peritoneal (V-P) shunt system equipped with anti-siphon device, did not show improvement of clinical signs and ventricular size on CT. While, the lumbar infusion manometric test in horizontal patient position showed good functioning of the shunting system in all 3 patients. However, the clinical signs and ventricular size on CT were remarkably improved by replacing the shunt system to the low pressure V-P shunt system which was not equipped with anti-siphon device. The shunt malfunction seemed to be caused by the anti-siphon function itself of the previous shunt system which was equipped with anti-siphon device, especially when the patients were kept sitting and/or standing during the daily activity.