Fixed versus Adjustable differential pressure valves in case of idiopathic normal pressure hydrocephalus treated with ventriculoperitoneal shunt. A systematic review and meta-analysis of proportion

•Adjustable DPVs with GASU are recommended to prevent complications in VP-shunted patients with iNPH.•Complication rates are lower with Adjustable DPV (with or without GASU) compared to fixed DPV.•Statistically significant benefit of adjustable DPV in preventing surgical revision of shunt is still not proven.