Pain in multiple system atrophy.

Pain is a recognized feature of idiopathic Parkinson's disease (IPD) but has never been studied in multiple system atrophy (MSA), the commonest cause of atypical parkinsonism. We retrospectively analysed histories of pain in 100 consecutive cases of clinically probable MSA. Details were obtained from the medical records of 100 patients with MSA, comprising 82 with the striatonigral degeneration (SND) type and 18 with the olivopontocerebellar atrophy (OPCA) type of MSA. Pain was reported in 47% of the MSA patients. It was classified as rheumatic in 64% of MSA patients reporting pain, sensory in 28%, dystonic in 21%, and levodopa-related in 16%, mostly related to off-period or diphasic dystonias. There was a mixed pain syndrome in 19% of these patients. Pain was significantly more commonly reported by females (P = 0.02), and by patients with levodopa-induced dyskinesias (P = 0.02). No other clinical feature differentiated MSA patients who reported pain from those who did not. The mean delay between disease onset and onset of pain was 2.9 years, but pain was reported at the time of, or before, disease onset in about 30% of patients. The overall prevalence of pain in MSA was similar to that reported in IPD, but the distribution of pain categories was different.