Disproportionately Enlarged Subarachnoid-space Hydrocephalus and Progressive Supranuclear Palsy
Muhui Fu1, Jeffery Gunter2, Ryota Satoh1, Rodolfo Gatto1, Farwa Ali1, Heather M. Clark1, Julie Stierwalt1, Mary Machulda1, Yehkyoung C. Stephens1, Hossam Youssef1, Nha Trang Thu Pham1, Clifford Jack1, Val Lowe1, Keith Josephs1, Jennifer Whitwell1
1Mayo Clinic, 2Mayo Clinic and Foundation
Objective:
We aimed to evaluate the prevalence of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) in parkinsonian disorders, including progressive supranuclear palsy (PSP), and evaluate associations with clinical features and imaging biomarkers.
Background:
Gait disturbance is the leading symptom of the Hakim’s triad of normal pressure hydrocephalus (NPH) and is also a cardinal feature of PSP. DESH is a distinct imaging pattern of NPH with undetermined frequency, clinical significance, and underlying mechanisms in parkinsonian disorders.
Design/Methods:
We conducted a cross-sectional study in 290 patients, including 181 PSP (62%), 36 corticobasal syndrome, 21 Parkinson’s disease, and 52 controls. An automated machine-based method for DESH (D) detection was applied to volumetric head MRI scans and DESH was determined as present (D+) or absent (D-). Using DESH classification plus a manual measurement for Evans’ index (E); cutoff > 0.3 = E+, patients were classified into four groups: Imaging-suggestive of hydrocephalus (D+E+), DESH positive only (D+E-), Evans’ index positive only (D-E+), and no imaging evidence of hydrocephalus (D-E-). Demographic, clinical and imaging metrics were ascertained and compared across groups.
Results:
Of the 290 patients, 214 were classified as: D+E+ (n=20); D+E- (n=8); D-E+ (n=71) and D-E- (n=115). 18/20 (90%) D+E+ cases were PSP. The D+E+ patients were older, had greater midbrain and cortical atrophy, more periventricular and deep white matter hyperintensities and larger cistern areas on MRI, lower striatal metabolism on [18f]fluorodeoxyglucose-PET and greater degeneration of long-range white matter tracts on diffusion tensor imaging, compared to the D-E- patients. D+E+ patients had a tendency to have hypermetabolism in the paracentral lobule on [18f]fluorodeoxyglucose-PET.
Conclusions:
DESH can be present in parkinsonian disorders, especially PSP, where it is associated with worse clinical and imaging outcomes. Its presence may be a mechanistic byproduct of degeneration that develop during the process of CSF flow re-distribution.
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