Abstract: Objective To compare the characteristics of the tremor of multiple system atrophy Parkinsonism type (MSA-P) with Parkinson's disease (PD), and improvement after acute levodopa challenge test. Methods From Match to September 2017, 70 patients with PD and 23 patients with probable MSA-P were included. All the patients were required of rest or postural tremor in at least one extremity or head, and accepted acute levodopa challenge test and analysis for dominant tremor frequency, amplitude and rhythm under resting state, posturing and holding 1000 g state, respectively.Results The score of Unified Parkinson Diease Rating Scale Part III was higher in MSA-P patients than in PD patients (t=-2.098, P<0.05), with less improvement after acute levodopa challenge test (Z=-9.446, P<0.01), while the tremor score and improvement were not significantly different between two groups (P>0.05). There were more frequence with non-alternating or synchronic tremor rhythm (χ²=8.756, P<0.01) and small irregular tremor in rest tremor (χ²=4.788, P<0.05) in MSA-P patients than in PD patients, as well as the high frequency tremor (>6 Hz) in postural tremor (χ²=11.312, P<0.01). The frequency of rest tremor was higher in MSA-P patients than in PD patients (t=-2.119, P<0.05), as well as the frequency of postural tremor with 1000 g (t=-2.274, P<0.05). Both PD and MSA-P patients showed, the lower frequency the postural tremor was, the higher the tremor scores were. There were 25% PD patients with head tremor, while none in MSA-P patients. Tremor score improved more than 30% after acute levodopa challenge test in 22.7% MSA-P patients, but none improved in UPDRS score. The frequence of tremor score improvement was more in female MSA-P patients than in males (P<0.05).Conclusion The features of the tremor are similar in PD and MSA-P, with some differences that MSA-P tend to higher frequency in rest or postural tremor, more non-alternating or synchronic tremor rhythm in rest tremor, and fewer has tremor besides limbs. Some MSA-P patients improve after acute levodopa challenge test, and women may improve more than men.

Key words: multiple system atrophy Parkinsonism type, Parkinson's disease, tremor, acute levodopa challenge test, tremor analysis