The treatment of infantile hydrocephalus: "differential-pressure" or "flow-control" valves - A pilot study

The choice of shunt valve in the treatment of hydrocephalus in children rem ains controversial. We embarked on a pilot study to determine the differenc es in outcome between differential-pressure and flow-regulating valves. Pro spective data collected on 50 consecutive first-time shunt insertions, perf ormed between June 1993 to June 1996, was analysed. Children with tumour- r elated hydrocephalus and Dandy-Walker malformations as well as children who had external ventricular drainage prior to definitive shunt insertion were excluded from the study. The defining event was the first complication nec essitating surgery, including obstruction, over-drainage and infection. Of the 50 children (31 males), 23 had differential pressure (medium-pressure) and 27 had Delta (performance level 2) valves inserted. The mean age at shu nt insertion was 26.4 months. The mean follow-up was 53.8 months. The overa ll cumulative shunt survival at 5 years was 58.6% for the differential pres sure and 58.7% for the Delta valves. The mean shunt life was 37.1 months fo r the differential pressure group and 34.6 months for the Delta group. This difference was not statistically significant (P=0.72, t-test). Both valves had a similar outcome with respect to obstruction (including proximal, val ve, distal). The main differences between the two valves were with respect to the incidence of over-drainage and infection. Amongst the differential p ressure valves, there were 4 instances of overdrainage (3 slit-ventricle sy ndrome, 1 bilateral subdural collection) - all occurring within the first 3 6 months. The Delta valve group had only one instance of over-drainage (bil ateral subdural collection). There were no infections in the differential p ressure valve group, whereas 3 of the Delta valve shunts got infected, all within the first month. Whereas both shunt types seemed to have a similar o verall survival, there was a relatively higher incidence of over-drainage a mongst the differential pressure valves. The Delta valves, on the other han d, had higher rates of infection. Similar studies with larger numbers could suggest whether the choice of shunt type will ultimately have to be a comp romise accepting one or the other complication.