[Shunt operation versus endoscopic ventriculostomy in normal pressure hydrocephalus: diagnostics and outcome].

In contrast to shunt operation the indication for an endoscopic ventriculostomy in patients diagnosed for normal pressure hydrocephalus is not scientifically established. From September 1997 to October 2001 we operated on 79 patients diagnosed for normal pressure hydrocephalus. Diagnosis was established by means of the intrathecal lumbal or ventricular infusion test, the cerebrospinal fluid tap test and MRI-CSF flow studies pre- and post-operatively. In 60 patients (76 %) we implanted a ventriculo-peritoneal shunt (Miethke Dual-Switch valve), and in 15 patients (19 %) we performed the endoscopic assisted third ventriculostomy. With our created NPH recovery rate and use of the clinical grading for normal pressure hydrocephalus created by Kiefer we compared the operative results of both patient groups. Immediately after the operation the results are the same for both treatments. In the follow-up examination after 12 and 27 months patients who underwent a ventriculostomy showed a better outcome, but the underdrainage rate was higher. Concerning the operation related complications the shunt treatment leaded to 10 revisions (17 %) because of four infections (7 %), two shunt insufficiencies (3 %), two overdrainages (3 %), two catheter dislocations (3 %). The ventriculostomy leaded to one case with a pneumatocephalus (7 %) and one ischemic thalamic lesion (7 %). In both operation methods we saw cases of underdrainages, three after valve implantation (5 %) and two after ventriculostomy (13 %). In that patients we performed a change of the implanted valve with a lower pressure level or rather an implantation of a valve system in the two cases who underwent a ventriculostomy. In patients with a pathologically increased resistance to CSF outflow in the lumbal infusion test a shunt implantation with the Miethke Dual-Switch valve is indicated. Patients whose outflow resistance is increased in the ventricular infusion test are suspected for a functional interventricular stenosis and should be treated by means of an endoscopic assisted ventriculostomy.