Effectiveness of Levodopa in Patients with Multiple System Atrophy and Associated Clinicopathological Features.

Objective To determine the clinicopathological features of levodopa or dopamine agonist (DA) responders with multiple system atrophy (MSA), an autopsy-confirmed diagnosis is vital due to concomitant cases of MSA and Parkinson's disease (PD). We therefore aimed to investigate the effectiveness of levodopa and DA in autopsy cases of MSA without PD and thereby clarify the clinical course, magnetic resonance imaging (MRI) findings, and pathological features of levodopa-responsive MSA cases. Methods The medical records (clinical data, MRI findings, and pathological findings) of 12 patients with MSA were obtained, and the patients were pathologically confirmed to not have PD. The clinical diagnoses of the patients were MSA with predominant parkinsonism (MSA-P) (n=7), MSA with predominant cerebellar ataxia (MSA-C) (n=4), and progressive supranuclear palsy (PSP) with a concomitant pathology of MSA (n=1). Results Nine patients received a maximum dose of 300-900 mg of levodopa as treatment, which was effective in two MSA-P patients and mildly effective in another two MSA-P patients. DA was mildly effective in one MSA-C patient. The levodopa responders showed marked autonomic dysfunction relatively late and became bedridden after 10 years. Additionally, they exhibited bilateral hyperintense putaminal rims in MRIs after six and nine years, respectively, after disease onset. One levodopa responder and one DA mild responder showed relatively mild neurodegeneration of the putamen. Conclusion Levodopa responders, despite having MSA-P, may show a relatively slow progression in putaminal neurodegeneration, and might maintain prolonged daily life activities in cases without an early occurrence of autonomic dysfunction.