gms | German Medical Science

Since last year a new G-valve, the Miethke GAV, is available. Its most important features are a low opening pressure (OP) in prone position and its small dimensions. We present our preliminary data.

26 patients suffering from a hydrodynamic proven chronic hydrocephalus of various ethiologies received a Miethke GAV. In all but one patients a ventriculoperitoneal drainage was preferred. To document the clinical course we used our own classification (Homburger Hydrocephalus Scale [HHS]). To measure the ventricular size we used the EVANS and FOHR index. The follow-up lasts between 2 - 14 months (average: 5 ± 3 months). Each patient was re-evaluated 2 and 12 months after operation. Statistics: Student's T-test; Spearman-rank-correlation (α = 5%).

20 patients received a GAV with an OP = 5cm H₂O in prone position. The patients experienced a significant clinical improvement, while the ventricular size reduction was only marginal. A correlation between clinical improvement and ventricular shrinking could not be verified. 65% of the patients experienced a good or excellent recovery, while 23% had to be termed as non-responders. Despite the usage of a low OP for prone position no overdrainage occurred even in cases of LOVA hydrocephalus, which bears a significant risk for this because of the large discrepancy between scull and brain volume. The most important complication was an allergy like irritation of the peritoneum in nearly 50% of the patients, which disappeared within 3 months without further treatment.

The results of the GAV are similar to those known from other G-valves. Most important: even with the usage of a relatively low OP for prone position we had no significance of an increased risk of overdrainage. This may be attributed to our policy to counteract the hydrostatic pressure a bit more aggressively than usual. The large number of peritoneal irritation cannot be explained.