On the Potential Benefit of Shunt Surgery in Idiopathic Normal-Pressure Hydrocephalus Patients with Alzheimer's Disease Pathology.

Many institutions rule out shunt surgery for idiopathic normal-pressure hydrocephalus (INPH) patients with Alzheimer's disease (AD) pathology. However, we believe some INPH patients with AD pathology might benefit from shunt surgery. While some reports suggest AD pathology may not adversely affect improvement after shunt surgery in INPH patients,1 the predominant position today is that AD pathology will adversely affect shunt surgery outcomes.2-4 For example, Hamilton et al.3 reported that INPH patients with moderate to severe AD pathology were associated with worse post-shunt outcomes. And Patel et al.4 reported INPH patients with high phosphorylated tau/amyloid beta 1-42 ratios showed less improvement following shunt surgery. Based on these studies, Jang et al.5 used amyloid positivity on positron emission tomography (PET) to exclude INPH patients for shunt surgery. However, the view that INPH patients with amyloid pathology should not have shunt surgery is likely based on older studies with less reliable methods and shorter follow-ups. We believe further studies are warranted to investigate whether some INPH patients with AD pathology can benefit from shunt surgery.