特発性正常圧水頭症（ハキム病）の病態と診断

Pathophysiology and Diagnosis of Idiopathic Normal Pressure Hydrocephalus (Hakim's Disease)

特発性正常圧水頭症（iNPH）は，脳室拡大に加え，シルビウス裂や脳底槽の拡大と高位円蓋部の脳溝狭小化といった脳の上方偏位が認められる特徴的な画像診断から，脳ドック検査で早期発見から早期治療につなげることが期待される疾患である。また，iNPH病態下ではアルツハイマー病やレビー小体病の併存頻度が高く，異常蛋白質が蓄積されやすい脳内環境にある。血液検査によるアミロイドβ病態の診断も報告されており，近い将来には，脳ドックによる画像検査と血液検査から，併存疾患も含めたiNPH診断が可能となる。

Abstract

Idiopathic normal-pressure hydrocephalus (iNPH) is a disease that can be detected early and treated promptly through neurological screening evaluations and brain imaging. Diagnosis is established based on characteristic clinical and imaging findings demonstrating not only ventricular enlargement but also tight high cortical subarachnoid spaces, along with enlargement of the Sylvian fissures and basal cisterns. Additionally, iNPH frequently coexists with neurodegenerative disorders such as Alzheimer's disease and dementia with Lewy bodies, suggesting that the iNPH brain environment is prone to abnormal protein accumulation. Recent advances in blood-based biomarker technology have enabled the detection of amyloid-β pathology in peripheral blood samples. Therefore, in the near future, the combined use of imaging studies and blood biomarker testing in neurodegenerative disease screening may support a more comprehensive diagnosis of iNPH, including its associated neurodegenerative comorbidities.