[Coexistence of progressive supranuclear palsy and idiopathic normal pressure hydrocephalus: pathophysiology and response to shunt surgery].

This review aims to summarize the frequency, pathophysiological features, and therapeutic effectiveness of shunt surgery in cases of coexisting progressive supranuclear palsy (PSP) and idiopathic normal pressure hydrocephalus (iNPH). In this review, we showed that the coexistence of these two disorders is not rare, that they may be related through the glymphatic system, and that in cases clinically suspected of having both conditions, improvement after shunt surgery may persist for one year or more, whereas in six pathologically confirmed cases, the duration of improvement was one year or less. However, the clinical characteristics of shunt-responsive patients among cases clinically suspected of having both conditions remain unclear. To address this issue, we are conducting a multicenter observational study to validate the usefulness of reduced frontal lobe blood flow on cerebral perfusion single-photon emission computed tomography, as previously reported.