Dysfunction of Holter Mini Elliptical valves caused by minor head trauma.

Two patients with implanted shunts suffered three disconnections of the shunt catheters from the valve chamber as a result of minor head trauma. In all instances a Holter Mini Elliptical valve had been used. The design of this valve may facilitate the kind of shunt dysfunction described. Suggestions are made for small changes in the shunt design or surgical procedures to obviate the vulnerability of the shunt to minor trauma.