Can preoperative brain imaging features predict shunt response in idiopathic normal pressure hydrocephalus? A PRISMA review

Purpose: This systematic literature review aimed to identify brain computed tomography (CT) and magnetic resonance imaging (MRI) features that could be used to discriminate idiopathic normal pressure hydrocephalus (iNPH) shunt responders from non-responders. Methods: PubMed, Embase, Web of Science, and Cochrane were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only original research articles reporting preoperative CT and/or MRI features and iNPH shunt response evaluated by changes in gait, dementia, and urinary incontinence were included. Title and abstract screening and full-text article evaluation were done by two authors. Data on patient demographics and inclusion criteria, brain image evaluation, shunting methods, and shunt response evaluation were recorded. Results: The search resulted in 1274 studies after removing duplicates. Twenty-seven studies were chosen for final review. Both structural (i.e., callosal angle, disproportionately enlarged subarachnoid space hydrocephalus (DESH), and temporal horn diameter) and physiological brain imaging (including aqueductal flow measurement and brain perfusion) had been examined. Fourteen out of 27 studies found no difference in any assessed imaging parameters between responders and non-responders, and none of the examined imaging parameters was repeatedly and consistently reported as significantly different between the two groups. Conclusions: No brain imaging parameters were consistently and repeatedly reported as different between iNPH shunt responders and non-responders.