Diagnosis and treatment of idiopathic normal pressure hydrocephalus (iNPH) based on the third edition of Japanese guidelines for management of iNPH

Hiroaki Kazui

Department of Neuropsychiatry, Kochi Medical School, Kochi University

Idiopathic normal pressure hydrocephalus（iNPH） is a highly prevalent condition present in 0.2% to 3.7% of the elderly population.　Tight high-convexity and medial subarachnoid spaces, and enlarged Sylvian fissures with ventriculomegaly, defined as disproportionately enlarged subarachnoid space hydrocephalus（DESH）, are common manifestations of iNPH.　DESH is useful in the differential diagnosis of iNPH and Alzheimer's disease（AD） and in predicting the efficacy of shunt surgery.　DESH is also useful in the early treatment of iNPH, as it can be detected even in asymptomatic patients.　Currently, 63% to 69% of patients with iNPH show clear improvement in ADLs when shunt surgery is performed.　Recent studies revealed that AD-related pathology is highly prevalent in iNPH, which may reduce the efficacy of shunt surgery.　In the future, it will be necessary to perform various biomarker examinations before shunt surgery to evaluate the coexistence of other diseases and to consider the indication for shunt surgery.

Address correspondence to Dr. Hiroaki Kazui, Department of Neuropsychiatry, Kochi Medical School, Kochi University（Kohasu Oko-cho, Nankoku, Kochi 783-8505, Japan）