The Overlap in Neuroimaging Findings Between Idiopathic Normal Pressure Hydrocephalus and Progressive Supranuclear Palsy

Background: The neuroimaging findings of brain stem atrophy resembling progressive supranuclear palsy (PSP) radiology are common in idiopathic normal pressure hydrocephalus (iNPH) subjects. Besides, recent studies report the existence of iNPH-like MRI findings in PSP subjects. We aimed to comparatively investigate the neuroimaging indices of iNPH and PSP in our patient groups in a detailed methodology. Methods: Ultimately, 19 probable PSP patients and 18 patients with a definite diagnosis of iNPH were enrolled. The subjects were recruited retrospectively from those who had been admitted between 2017 and 2021 to the Movement Disorders Polyclinic and the Neurosurgery Clinic of the Diskapi Yildirim Beyazit Training and Education Hospital. MRI-based DESH score, Evans index, and the callosal angle (CA) have been calculated in all the individuals. Besides, quantitative MRI parameters of PSP were evaluated in every subject. Statistical analyses were performed using IBM SPSS Statistics 26. Results: The comparative analyses regarding the radiological parameters of PSP did not reveal any difference between patient groups. On the other hand, the comparisons of the neuroimaging parameters of iNPH, yielded differences in the CA, CA score, and the total DESH score. However, the ROC curve analyses did not reveal a discriminative power at a value of "very good" or "excellent" in any of the indices. Conclusions: We found that the neuroimaging features of iNPH and PSP highly overlapped between these patient groups. These results may provide indirect evidence regarding the coexistence of PSP and iNPH pathophysiology that has been deliberated in several recent reports.