Progression of parkinsonism in multiple system atrophy

Background Progression of parkinsonian motor impairment is usually rapid and relentless in multiple system atrophy (MSA). However, it may also be subject to considerable variation. Prospective natural history studies using validated rating scales are required to accurately determine the progression of parkinsonism in MSA. Objective To assess the progression of parkinsonism in patients with the Parkinson variant of MSA. Methods Parkinsonian motor impairment was assessed on regular therapy at two time points ( mean follow-up 11.8 months, SD 1.4) using the Hoehn and Yahr scale (H&Y), the Schwab and England ADL scale (SES) and the motor examination section of the UPDRS (UPDRS-III) in 38 patients with clinically probable MSA-P. Results We examined 38 patients with probable MSA-P ( mean age 63.2 years, SD 7.4; mean disease duration 4.1 years, SD 3.0). The mean difference of UPDRS-III between baseline and follow-up was 10.8 95% CI 8.6 - 12.9), consistent with an average annual 28.3% increase of UPDRS-III baseline scores. Several variables were associated with faster progression of parkinsonism including low baseline global motor disability as assessed by H&Y and SES, low baseline UPDRS III score, and short disease duration. UPDRS-III progression was unrelated to gender, age at symptom onset, and age at baseline visit. Conclusion This is the first observational study on UPDRS rates of decline in MSA. The observed 28.6% annual increase of UPDRS-III scores illustrates the rapid progression of motor impairment in MSA. Furthermore, motor progression appeared to be accelerated during the early disease stages. Our data allow sample size calculations that may be helpful for the planning of future therapeutic trials.