Disproportionately enlarged subarachnoid-space hydrocephalus (DESH) in normal pressure hydrocephalus misinterpreted as atrophy: autopsy and radiological evidence.

Disproportionately enlarged subarachnoid-space hydrocephalus (DESH), a feature of normal pressure hydrocephalus (NPH), is often misinterpreted as cortical atrophy. We report a 67-year-old man with features of NPH but not diagnosed because radiographic findings were interpreted as cortical atrophy. Autopsy showed findings consistent with NPH and no neurodegenerative disease. The second patient with DESH underwent shunt surgery. Entrapped fluid diminished after the surgery, confirming this is not atrophy, but due to a CSF dynamic process. Patients with DESH have tight sulci adjacent to the entrapped fluid pockets, distinguishing it from cortical atrophy. 18F-Fluorodeoxyglucose PET can help differentiate DESH from cortical atrophy.