Disproportionately Enlarged Subarachnoid-Space Hydrocephalus on MRI in Pathologically Confirmed Progressive
Miki Kawazoe1,2, Shunsuke Koga1, Hiroaki Sekiya1
1Department of Neuroscience, Mayo Clinic, Jacksonville, FL.
Neurology. Clinical Practice
|February 26, 2025
Summary
Idiopathic normal-pressure hydrocephalus (iNPH) imaging markers like DESH and Evans index may not be specific. These findings in progressive supranuclear palsy (PSP) and Lewy body disease (LBD) could lead to misdiagnosis and unnecessary iNPH surgery.
Area of Science:
- Neuroscience
- Neurology
- Radiology
Background:
- Idiopathic normal-pressure hydrocephalus (iNPH) can present with symptoms mimicking other neurodegenerative conditions.
- Progressive supranuclear palsy (PSP) and Lewy body disease (LBD) share clinical and imaging similarities with iNPH.
- Accurate differentiation is crucial for appropriate patient management and avoiding unnecessary interventions.
Purpose of the Study:
- To investigate the presence and significance of iNPH-associated imaging features in patients with autopsy-confirmed PSP or LBD.
- To assess the specificity of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) and Evans index (EI) in differentiating iNPH from PSP and LBD.
- To evaluate the frequency of the NPH triad of symptoms in relation to imaging findings in these neurodegenerative diseases.
Main Methods:
- Retrospective analysis of 190 patients with autopsy-confirmed PSP (n=101) or LBD (n=89).
- Antemortem MRI scans were evaluated for DESH and high EI.
- Logistic regression analyses were performed to compare imaging features between PSP and LBD groups, adjusting for age, sex, and brain weight.
Main Results:
- DESH was more frequent in LBD (13%) than PSP (3%), while high EI was similar between groups (36% vs 32%).
- Adjusted analyses showed no significant difference in the likelihood of DESH or high EI between PSP and LBD.
- Mean age at death and brain weight were significantly different between PSP and LBD.
Conclusions:
- Imaging markers DESH and high EI, commonly associated with iNPH, may lack specificity.
- These findings suggest that DESH and high EI can be present in a subset of patients with PSP or LBD.
- Misinterpretation of these imaging features could lead to the misdiagnosis of iNPH and subsequent unnecessary neurosurgery.
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