Abstract
PurposeThe 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.MethodsWe 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.ResultsFor 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.ConclusionMRPI 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.
Highlights
Material and methodsIdiopathic normal pressure hydrocephalus is a potentially treatable syndrome characterized by a variable combination of impaired gait, cognition, and urinary dysfunction [1]. idiopathic normal pressure hydrocephalus (iNPH) can be diagnosed by medical history, neurologic examination, and brain imaging with CT or MRI
Magnetic Resonance Parkinsonism Index (MRPI) and MRPI 2.0 significantly overlap in iNPH and progressive supranuclear palsy (PSP), with risk of misdiagnosis, and for this reason may not be helpful in the differential diagnosis
When the interpeduncular angle (IPA) measurements were evaluated, this metric proved to be equivalent between PSP patients and healthy controls (HC) (p < 0.01), and not different (p = 0.93), while it was significantly higher in iNPH patients compared with both PSP and control groups (p < 0.01 in both cases), being not equivalent (p = 0.96 and 0.82, respectively)
Summary
Material and methodsIdiopathic normal pressure hydrocephalus (iNPH) is a potentially treatable syndrome characterized by a variable combination of impaired gait, cognition, and urinary dysfunction (urgency and incontinence) [1]. iNPH can be diagnosed by medical history, neurologic examination, and brain imaging with CT or MRI. Idiopathic normal pressure hydrocephalus (iNPH) is a potentially treatable syndrome characterized by a variable combination of impaired gait, cognition, and urinary dysfunction (urgency and incontinence) [1]. Progressive supranuclear palsy (PSP) shares with iNPH some of the cardinal clinical features, i.e., gait dysfunction, postural instability with retropulsion, and cognitive impairment [2]. PSP could be distinguished from iNPH based on other specific features, in particular the typical ocular motor dysfunction, characterized by supranuclear gaze palsy or slowing of vertical saccades. The ocular motor dysfunction can be missing in the early stages of PSP, especially in non-Richardson’s phenotypes [2]. The urinary dysfunction is a classical feature of iNPH, but can be a non-specific and frequent finding in a population older than 60 years [3]
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