[The diagnostic value of urethral sphincter electromyography in patients with multiple system atrophy].

OBJECTIVE: To analyze diagnostic evaluation of urethral sphincter electromyography (US-EMGs) for patients with multiple system atrophy (MSA).

METHODS: Totally 15 patients who were diagnosed as MSA were examined as treatment group while 17 non-MSA patients were examined as controls. US-EMGs were performed in the both groups. Spontaneous activities when relax, parameters of motor unit potentials (MUPs) mean duration and amplitude, percentage of polyphasic ware, satellite potential, recruitment potentials and amplitude when strong contraction were recorded and analyzed.

RESULTS: US-EMGs changes of various abnormalities were found in 13 cases (86.7%) in MSA group. There were significant differences of electromyographic findings between the MSA group and control group including MUPs mean duration [(12.79 ± 3.18) ms vs (9.49 ± 1.51) ms] and amplitude [(828.53 ± 459.89) µV vs (378.76 ± 152.26) µV] as well as recruitment potentials [(11.47 ± 21.55)% vs (8.23 ± 10.74)%] and amplitude [(2.19 ± 1.24) mV vs (0.75 ± 0.42) mV] when strong contraction (all P values < 0.05).

CONCLUSIONS: There is certain value of US-EMGs for the diagnosis of MSA. It could be used as a routine electrophysiological method for the patients who are suspected of MSA. It could be a supplement of external anal sphincter electromyography.