gms | German Medical Science

Objective: Since the introduction of gravitational assisted valves (GAV) overdrainage in patients with ventriculoperitonal shunts became treatable. However, there are no data suggesting a reliable choice of GAV differential pressure. We set up a retrospective analysis of patients successfully treated with ventriculoperitoneal shunts including a GAV for any kind of hydrocephalus.

Method: Patients had to fulfill the following criteria: ventriculoperitonal shunt with any fix or adjustable gravitational assisted valve, best possible adjustment of any signs of over- and underdrainage, full access to clinical data and latest CT scans. The vertical effective differential pressure was determined according to GAV position and serial valves.

Results: 122 patients were eligible for this study. Female patients revealed a higher vertical effective differential pressure (VEDP) compared to males (mean 35.6 cmH₂O (SD ± 2.46) vs. 28.9 cmH₂O (SD ± 0.87), respectively, p=0.0072, t-test). According to the body mass index (BMI) this finding sustained in overweight and obese, but not in the normal or underweight patients (BMI>25: n=75, 35.6 cmH₂O (SD ± 3.17) vs. 28.3 cmH₂O (SD ± 0.6), p=0.016; BMI≤25: n=47, 35.5 cmH₂O (SD ± 4.0) vs. 29.7 cmH₂O (SD ± 2.11), p=0.190). Over the age of 60 years lower VEDP by mean of 6.76 cmH₂O ± 2.37 (p=0.0051) were needed. Total BMI and height did not correlate to VEDP. Evans index and presence of subdural effusion revealed no gender dependency (p=0.7126 and 0.2103 Fishers Exact Test, respectively)

Conclusions: The need for higher vertical differential pressure in female patients is restricted to overweight patients and is correlated to age under 60 years. As, so far, no reliable factors predict the gravitational valve setting, adjustable gravitational valves should be considered.