Diffuse putaminal degeneration without iron deposition in multiple system atrophy.

BackgroundMultiple system atrophy (MSA) is a progressive neurodegenerative disorder characterized by parkinsonism, cerebellar ataxia, and autonomic dysfunction. Putaminal hypointensities on T2 magnetic resonance imaging (MRI) are commonly observed in the parkinsonian variant of MSA (MSA-P).ObjectiveTo report a neuropathologically confirmed case of MSA-P with an atypical MRI presentation, characterized by progressive T2 hyperintensity in the putamen, without significant iron accumulation.MethodsWe present the clinical course, imaging findings, and neuropathological results of a 57-year-old woman with MSA-P. Diagnostic evaluations included serial brain MRI, cerebrospinal fluid analysis, magnetic resonance spectroscopy, and post-mortem pathological examination.ResultsThe patient initially presented with L-dopa-responsive bradykinesia and right-dominant rigidity, followed by progressive motor decline, orthostatic hypotension, and urinary retention. Serial T2-weighted MRI revealed diffuse and progressively increasing hyperintensity in the putamen, accompanied by atrophy predominantly on the left side. Autopsy confirmed the diagnosis of MSA, revealing severe neuronal loss, marked gliosis, and abundant glial cytoplasmic inclusions in the putamen, with only mild iron deposition as shown by Prussian blue staining.ConclusionsThis case demonstrates that severe putaminal neurodegeneration in advanced MSA can be associated with progressive T2 hyperintensity on MRI, reflected by the absence of substantial iron deposition. These findings indicate that iron-independent mechanisms contribute to the pathophysiology of MSA-related putaminal damage in patients with MSA.