By Peter Sergo, medwireNews Reporter
Using a shunt with an adjustable Strata valve that is initially set at the highest setting so it can be titrated down is a worthwhile approach to treat idiopathic normal pressure hydrocephalus (INPH).
Researchers show that a ventriculoperitoneal shunt equipped with an antisiphon device as well as an adjustable valve that is initially set at a high opening pressure can be calibrated until signs of improvement or overdrainage are reached, resulting in fewer cases of subdural effusion (SDE).
"Using this protocol leads to significantly fewer SDEs compared with starting at a low setting," conclude Ernst Delwel (Erasmus University Medical Center, Rotterdam, the Netherlands) and colleagues. "However, it should be noted that starting with a high setting might delay clinical improvement and lead to more valve adjustments than starting at a low pressure setting," he cautions in the Journal of Neurology, Neurosurgery and Psychiatry.
The multicenter prospective randomized trial included 58 patients with suspected INPH, 48 of whom took part until the final 9-month follow up. In the control group of 30 patients, a Strata shunt was implanted with the valve preset at a performance level (PL) of 1.0, while in the remaining 28 patients it was preset at PL 2.5 and subsequently lowered until improvement or radiologic signs of overdrainage occurred.
Improvement was defined as the absence of SDE, along with at least a 15% improvement on tests for either gait or cognitive function. Urinary incontinence, in addition to gait and cognitive symptoms, define the "clinical triad" that typically characterizes INPH symptoms and was among the secondary outcomes.
Overall, there was no significant difference in improvement between groups at the study end, with 73.1% of the control group and 76.9% of the experimental group showing clinical progress as defined by the primary outcome.
The authors note that the high PL group had a nonsignificant "plateau" in improvement for gait, cognitive, and functional score between 1 and 3 months follow up while controls improved over the same period. The former group was also more at risk for falling accidents and required more valve adjustments (67.9 vs 23.3% in control group) due to failure to improve or SDE correction.
While subdural hematomas were absent, the control group had significantly more SDE than the group that underwent valve adjustment at the 1-month (24 vs 0%) and 9-month (47.6 vs 14.3%) follow ups. This difference was nonsignificant when restricted to patients who had clinical improvement; at 9 months, SDE occurred in eight (53.3%) of 15 PL 1.0 patients compared with two (10.5%) of 19 PL 2.5 patients.
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