[Comparative study on diagnostic significance of urethral sphincter versus external anal sphincter electromyography in patients with multiple system atrophy].

OBJECTIVE

To evaluate the diagnostic value of external anal sphincter electromyography (EAS-EMG) versus urethral sphincter electromyography (US-EMG) in patients with multiple system atrophy (MSA).

METHODS

A total of 27 MSA patients were examined with EAS and US-EMG as treatment group while 28 non-MSA subjects as control group. Spontaneous activities during relaxation, mean duration & amplitude of motor unit potential (MUP), percentage of polyphasic and variations during strong contraction were recorded and analyzed statistically.

RESULTS

There was significant difference in light contraction between MSA and non-MSA cases on both EAS-EMG and US-EMG (EAS-EMG, P < 0.001; US-EMG, P = 0.002) . Meanwhile, strong contraction and percentage of polyphasic showed significant differences between MSA and non-MSA cases on EAS-EMG only (strong contraction, P = 0.016; percentage of polyphasic, P = 0.004) . EAS-EMG showed more significant changes in neurogenic injury than US-EMG.

CONCLUSIONS

US-EMG and EAS-EMG are valuable for the diagnosis of MSA. The differences of multiple parameters of EAS-EMG were more significant than those of US-EMG for MSA cases. US-EMG may serve as a supplement of EAS-EMG in case of restriction.