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The following is a summary of “Disproportionately Enlarged Subarachnoid-Space Hydrocephalus on MRI in Pathologically Confirmed Progressive Supranuclear Palsy,” published in the February 2025 issue of Neurology Clinical Practice by Kawazoe et al. 

Idiopathic normal-pressure hydrocephalus (iNPH) can mimic neurodegenerative disorders like progressive supranuclear palsy (PSP).  

Researchers conducted a retrospective study on iNPH clinical and neuroimaging features in autopsy-confirmed PSP and Lewy body disease (LBD). They assessed the normal pressure hydrocephalus (NPH) triad, disproportionately enlarged subarachnoid-space hydrocephalus (DESH), and Evans index (EI) on antemortem MRI scans. 

They analyzed 190 patients (mean age 76.8 ± 9.2 years, 134 (70.5%) male) with autopsy-confirmed PSP (n = 101) or LBD (n = 89) from Mayo Clinic, excluding those with Alzheimer disease or hydrocephalus-related disorders. Logistic regression assessed DESH and high EI on MRI, adjusting for age, sex, and brain weight. The NPH triad was evaluated relative to imaging findings. 

The results showed that DESH and high EI were similar between PSP and LBD. The mean age at death was higher in LBD (80.0 ± 9.2) than in PSP (74.0 ± 8.2), and brain weight was greater in LBD (1,300 ± 150) than in PSP (1,190 ± 123) (P < 0.001 each). DESH was more frequent in LBD than PSP (13% vs 3%, P = 0.004), while high EI was similar (36% vs 32%, P = 0.500). Adjusted ORs for DESH (0.3, 95% CI 0.06–1.25, P = 0.119) and high EI (1.8, 95% CI 0.86–4.06, P = 0.120) were also similar. 

Investigators found that DESH and high EI, considered biomarkers for iNPH, lacked specificity and were present in some patients with PSP or LBD, potentially leading to unnecessary neurosurgery. 

Source:neurology.org/doi/10.1212/CPJ.0000000000200431