3-Hz postural tremor in multiple system atrophy cerebellar type (MSA-C)—a static posturography study

The objective of the study is to evaluate postural dysfunction of multiple system atrophy-parkinsonian type (MSA-P) and cerebellar type (MSA-C) by static posturography exam. A total of 29 MSA-P patients, 40 MSA-C patients, and 23 healthy controls (HC) were recruited and engaged in a sensory organization test (SOT). The amplitude of the postural sway was measured and transformed into energy value by Fourier analyzer. SOT scores, frequency of falls and typical 3-Hz postural tremors during the four stance tasks, and energy value in three different frequency bands were recorded and compared. Compared with HC, SOT scores were significantly lower in MSA groups ( P < 0.01). Compared with MSA-P, the vestibular scores were further reduced in MSA-C patients ( P < 0.05). Falls were more frequent in MSA groups, especially in SOT4 task (foam surface with eyes closed) or in MSA-C group ( P < 0.05). Typical 3-Hz postural tremor was observed in 97.5% MSA-C patients, in 24.1% MSA-P patients but in none of the HC ( P < 0.05). Compared with HC, much more energy was consumed in every task, every direction, and nearly every frequency band in MSA groups. Energy value of MSA-C group was significantly higher than that of MSA-P, especially in higher frequency band (2 ~ 20 Hz) or in more difficult stance tasks (SOT 3 ~ 4, foam surface with eyes open or closed) ( P < 0.05). Both MSA-P and MSA-C were characterized by severe static postural dysfunction. However, typical 3-Hz postural tremor was predominant in MSA-C and was very useful in the differential diagnosis between MSA-P and MSA-C.