Experiences with flow-regulated shunts (Orbis-Sigma valves) in cases of difficulty in managing hydrocephalus in children.

Due to an increasing number of shunt complications with conventional valves, we performed a study of 80 flow-regulated Orbis-Sigma valves implanted in 47 children who had had repeated complications with conventional valves and 33 children receiving their first shunt. The results were encouraging. During the first 5 years after implantation, the probability of absence of any kind of surgical intervention to the valve system was 57% and the probability satisfactory function of the valve itself was 70%. The most frequent complication was underdrainage of CSF, especially in children under the age of 1 year. No cases of CSF overdrainage occurred in this series. The Orbis-Sigma valve appears especially useful for patients unable to tolerate the anti-siphon device, and for patients over 1 year old receiving their first valve for hydrocephalus of non-tumoral and non-haemorrhagic origin.