Pitfalls in shunting of hydrocephalus--clinical reality and improvement by the hydrostatic dual-switch valve.

The hydrostatic dual-switch valve (DSV) was implanted in 56 patients suffering from hydrocephalus of different causes. Evaluation of the clinical status 3 and 6 months after the operation revealed excellent and good neurological recoveries in the vast majority of cases. Only 7 patients demonstrated an unsatisfactory result according to the grading of Stein and Langfitt. The CT follow-up, evaluated by the reduction of the Evans index, was characterized by only minimal or even no reduction of the ventricular size in more than half of the patients. Only 2 patients of our series developed overdrainage-related problems. 5 cases are presented to illucidate the danger of overdrainage resulting from the implantation of conventional differential-pressure valves, and the possible solution of this problem by hydrostatic devices like the DSV. Our series gives strong evidence, that reestablishing physiological pressure-ranges after shunting is paralleled by a good clinical outcome independent of the ventricular size after shunting.