Progressive supranuclear palsy often develops idiopathic normal pressure hydrocephalus-like magnetic resonance imaging features

Background and purpose Idiopathic normal pressure hydrocephalus (iNPH) is a clinical entity without established pathological hallmarks. Previous autopsy studies reported that patients with an antemortem diagnosis of iNPH had a different postmortem diagnosis, commonly progressive supranuclear palsy (PSP). Disproportionately enlarged subarachnoid space hydrocephalus (DESH) has been reported as a characteristic feature of iNPH on magnetic resonance imaging (MRI). In addition, periventricular white matter hyperintensities (PVHs) are noted in most patients with iNPH; these PVHs are supposed to reflect transependymal movement of ventricular cerebrospinal fluid. It is hypothesized that PSP develops more iNPH-like MRI features than other neurodegenerative disorders. Methods Thirty-eight patients with a clinical diagnosis of PSP, 42 with Parkinson's disease (PD) without dementia, 30 with PD with dementia (PDD) and 29 with Alzheimer's disease (AD) were enrolled. The DESH score and PVH grade were measured using the conventional MRI sequence and were compared amongst the patient groups. Results Disproportionately enlarged subarachnoid space hydrocephalus score was significantly higher in patients with PSP than PD without dementia, and there was a trend that the DESH score was higher in patients with PSP than PDD or Alzheimer's disease. PVH grade was significantly larger in patients with PSP than PD without dementia. In the components of the DESH score, callosal angle was significantly smaller in patients with PSP than in PD without dementia or PDD. Conclusions This study demonstrated that some PSP patients develop iNPH-like MRI features, suggesting the presence of iNPH-like features in the clinical spectrum of PSP. A clinical phenotype of PSP with hydrocephalus is proposed, which should be further investigated in future studies.