Clinical Experience With a Dual Switch Valve (Miethke) for the Management of Adult Hydrocephalus

The dual switch valve (DSV), which switches between two parallel valve chambers depending on the patient posture, was evaluated in 101 consecutive adult patients with hydrocephalus who required shunt surgery. The opening pressure was 5 or 10cm H_2O for the supine position and 30 or 40cm H_2O for the upright position depending on the sitting height. The results clearly showed that the DSV can regulate the intraventricular pressure (IVP) to 5 to 10cm H_2O in the supine and almost zero in the upright position, independently of posture. Ninety-four of the 101 patients received the DSV and 86 patients showed some clinical improvement. However, three patients required irrigation of subdural hematoma and six were thought to suffer underdrainage (4 probable and 2 possible). Such underdrainage probably resulted from the relatively high opening pressure in the supine position of 10cm H_2O and the bedridden state of these patients. This problem may be solved by the DSV with the 5cm H_2O setting in the supine position. The DSV can maintain physiological IVP in hydrocephalic patients independently of posture and provides generally satisfactory clinical outcome, but cannot prevent all inadequate drainage-related problems.