Abstract
BackgroundParkinsonian variant of multiple system atrophy is a neurodegenerative disorder frequently misdiagnosed as Parkinson’s disease. No early imaging biomarkers currently differentiate these disorders.MethodsSimple visual imaging analysis of the substantia nigra and locus coeruleus in neuromelanin-sensitive magnetic resonance imaging and nigrosome 1 in susceptibility-weighted sequences was performed in thirty patients with parkinsonian variant of multiple system atrophy fulfilling possible/probable second consensus diagnostic criteria. The neuromelanin visual pattern was compared to patients with Parkinson’s disease with the same disease duration (n = 10) and healthy controls (n = 10). Substantia nigra semi-automated neuromelanin area/signal intensity was compared to the visual data.ResultsGroups were similar in age, sex, disease duration, and levodopa equivalent dose. Hoehn & Yahr stage was higher in parkinsonian multiple system atrophy patients, 69% of whom had normal neuromelanin size/signal, significantly different from Parkinson’s disease patients, and similar to controls. Nigrosome 1 signal was lost in 74% of parkinsonian multiple system atrophy patients. Semi-automated neuromelanin substantia nigra signal, but not area, measurements were able to differentiate groups.ConclusionsIn patients with parkinsonism, simple visual magnetic resonance imaging analysis showing normal neuromelanin substantia nigra and locus coeruleus, combined with nigrosome 1 loss, allowed the distinction of the parkinsonian variant of multiple system atrophy from Parkinson’s disease and healthy controls. This easy and widely available method was superior to semi-automated measurements in identifying specific imaging changes in substantia nigra and locus coeruleus.
Highlights
Parkinsonian variant of multiple system atrophy is a neurodegenerative disorder frequently misdiagnosed as Parkinson’s disease
Levodopa equivalent daily dose (LEDD) was not different but Hoehn & Yahr stage (HY) stage was higher in motor symptom as parkinsonian (MSA-P) (2.5 ± 0.5 vs. 2.0 ± 0.0, p < 0.001)
Simple visual analysis of Substantia nigra (SN) and locus coeruleus (LC) in Multiple system atrophy (MSA)-P patients Neuromelanin visual analysis SN size was normal in 69% (20/29)
Summary
Parkinsonian variant of multiple system atrophy is a neurodegenerative disorder frequently misdiagnosed as Parkinson’s disease. No early imaging biomarkers currently differentiate these disorders. Multiple system atrophy (MSA) is a sporadic, adult-onset and rapidly progressive neurodegenerative disorder, involving striatonigral, olivopontocerebellar, pyramidal, and autonomic systems. The parkinsonian variant (MSA-P) has significant clinical overlap with Parkinson’s disease (PD), leading to frequent misdiagnosis [2], especially in the early stages, when red flags may be absent [3]. A post mortem study of neuropathologically-confirmed MSA-P showed that most patients were initially clinically diagnosed as PD and in half, the diagnosis was later changed to MSA [2]. Less prevalent than PD, this devastating disorder is an important differential diagnosis to consider when evaluating a patient presenting with parkinsonism as there are significant prognostic and therapeutic implications. New magnetic resonance imaging (MRI) sequences have been recently developed, allowing the visualization of SN and LC in vivo and correlating with neuronal loss and iron deposition, two hallmarks of neurodegeneration [6,7,8,9,10,11,12,13,14,15,16,17]
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