Magnetic resonance parkinsonism indices and interpeduncular angle in idiopathic normal pressure hydrocephalus and progressive supranuclear palsy

Abstract

Purpose The clinical presentation of idiopathic normal pressure hydrocephalus (iNPH) may overlap with progressive supranuclear palsy (PSP). The Magnetic Resonance Parkinsonism Index (MRPI), MRPI 2.0, and the interpeduncular angle (IPA) have been investigated to differentiate PSP from healthy controls (HC) and other parkinsonisms. We aimed to assess equivalences and differences in MRPI, MRPI 2.0, and IPA in iNPH, PSP, and HC groups. Methods We retrospectively recruited 99 subjects (30 iNPH, 32 PSP, 37 HC) from two institutions. MRI exams, acquired on either 1.5 T or 3 T scanners, included 3D T1-weighted images to measure MRPI, MRPI 2.0, and IPA. Inter-and intra-rater reliability was investigated with the intra-class correlation coefficient (ICC), and the two one-sided t tests (TOST) procedure was used to assess these markers in iNPH, PSP, and HC. Results For all the three measures, intra-rater and inter-rater ICC were excellent (range = 0.91-0.93). In the comparison of iNPH and PSP with HC, differences for MRPI and MRPI 2.0 (p < 0.01 in all cases) and no equivalence (p = 1.00 in all cases) were found at TOST. iNPH and PSP MRPI showed no difference (p = 0.06) and no equivalence (p = 0.08). MRPI 2.0 was not equivalent (p = 0.06) and not different (p = 0.09) in the same two populations. PSP and HC IPA proved equivalent (p < 0.01) while iNPH IPA was different (p < 0.01) and not equivalent (p = 0.96 and 0.82) from both PSP and HC. Conclusion MRPI and MRPI 2.0 significantly overlap in iNPH and PSP, with risk of misdiagnosis, and for this reason may not be helpful in the differential diagnosis.

Higher prevalence of idiopathic normal pressure hydrocephalus‐like MRI features in progressive supranuclear palsy: An imaging reminder of atypical parkinsonism

“…Traditionally, NPH and PSP are classified as two distinct diseases and should be thoroughly distinguished to avoid futile treatment. Several researchers tried to find additional MRI indexes differentiating one from the other, such as Magnetic Resonance Parkinsonism Index, Magnetic Resonance Hydrocephalic Index, interpeduncular angle, midbrain area, and cortical thickness (Bianco et al., 2022; Ohara et al., 2020 ; Quattrone et al., 2020 ; Ugga et al., 2020 ; Virhammar et al., 2022). In our opinion, a portion of the two entities does overlap and share similar features, implying the transitory role of NPH mimics in the clinical course of PSP.…”

Is MRPI 2.0 More Useful than MRPI and M/P Ratio in Differential Diagnosis of PSP-P with Other Atypical Parkinsonisms?

“…MRPI 2.0 has been found to be more feasible for evaluating PSP progression [ 17 ]. A more recent study showed certain limits to the usefulness of MRPI and MRPI 2.0 since significant overlaps were found with normal pressure hydrocephalus and PSP [ 18 ].…”

Pathologically Verified Corticobasal Degeneration Mimicking Richardson's Syndrome Coexisting with Clinically and Radiologically Shunt‐Responsive Normal Pressure Hydrocephalus

“… 1 To avoid the misdiagnosis of NPH and other neurodegenerative disorders, especially in patients with PSP who exhibit the clinical triad of NPH symptoms, radiological biomarkers with MRI are suggested. 11 , 12 Distinguishing NPH from neurodegenerative disorders is necessary to avoid shunt‐related complications such as infection and headache because shunt surgery is not likely to have beneficial effects in patients with neurodegenerative disorders.…”

“…A literature review of NPH studies indicated that the benefits of shunt implantation in patients with an initial diagnosis of idiopathic NPH persisted in only 32% of patients at 36 months, leading to a revised diagnosis in more than 25% of patients (AD, DLB, and PSP) 1 . To avoid the misdiagnosis of NPH and other neurodegenerative disorders, especially in patients with PSP who exhibit the clinical triad of NPH symptoms, radiological biomarkers with MRI are suggested 11,12 . Distinguishing NPH from neurodegenerative disorders is necessary to avoid shunt‐related complications such as infection and headache because shunt surgery is not likely to have beneficial effects in patients with neurodegenerative disorders.…”