Clinical experiences with the Miethke-Dual-Switch valve in patients with normal pressure hydrocephalus

In patients with normal pressure hydrocephalus (NPH) the conventional diffe rential pressure valve has the disadvantage of opening abruptly when the pa tient moves into an upright position. a strong suction at the already atrop hic brain could therefore result. Can this disadvantage and especially the complication of overdrainage be reduced or solved by a hydrostatic valve? I n 128 patients diagnosed for NPH we implanted a Miethke Dual- Switch valve. All patients were reevaluated 7 months after surgical treatment in our mul ticentre study. The evaluation of the course of disease showed in 63% of ca ses an excellent outcome, in 16% a satisfactory and in 21% of the patients a bad outcome. The patients, outcome correlated with the preoperative sever ity of the disease scored using the Kiefer scale. Complications as well as the valve pressure levels are discussed in the paper. We also present the t echnical principles of this new valve technology. With a overdrainage rate of 2% and a shunt-related lethality of 0% the rate of complications of the Miethke Dual-Switch valve is clearly lower than started in international li terature. The clinical course of patients suffering from NPH is influenced by the stage of the disease, the beginning of therapy and the implanted val ve type. Despite restricted clinical experience with the Miethke Dual-Switc h valve we emphasise the advantages of this valve for patients with NPH.