ELECTROMYOGRAPHICAL STUDY OF THE URETHRAL SPHINCTER IN PARAPLEGIC PATIENTS
The Japanese Journal of Urology
To investigate the role of sphincter activity in the voiding dysfunction of spinal cord injury, 103 paraplegics were studied by electromyography of both urethral and anal sphincter. Electromyographical activity was recorded with single core needle electrodes. The external urethral sphincter was identified at the apex of the prostate by the intrarectal digital palpation under visual or audio control; the external anal sphincter was found without difficulty in subcutaneous position. (1) Average
... urethral and anal EMG activity was 0. 450. 55 mV and 0. 370. 48 mV, respectively. (2) The activity of these two sphincters was identical in 60 percent, while it was dissociated completely in 25 percent and partially in 15 percent. (3) Correlation between voiding dysfunction and either residual urine or micturition time was statisticaly analyzed to see if these parameters reflect voiding dysfunction. They were formed to be clinically usable (n=89, r=0. 619, t=7. 36>t. 01=2. 66). (4) Correlation between urethral MEG-activity and residual urine was n=89, r=0. 539, f=5. 97>t. 01=2. 66. Correlation between urethral EMG activity and micturition time was n=89, r%0. 429, t=4. 44>t. 01=2. 66. These data suggested that urethral EMG activity correlated very well with dysfunction as evidenced by residual urine or voiding time. ( 5 ) Similar statisticaly analysis of the anal EMG activity revealed no significant correlation either to residual urine or micturition time. Anal sphincter seems to be unreliable in predicting voiding dysfunction. (6) Activity of the two sphincters was compared in the group with and without voiding dysfunction. Urethral EMG activity was found to be statistically more significant in the latter than in the former group. Anal EMG activity was variable without any statistical significance between the two groups. (7) There was a statistically significant trend of increasing urethral EMG activity as the level of spinal injury assends -0. 670. 64 mV, 0. 510. 57 mV, and 0. 200. 33 mV in the cervical, thoracic, and lumbar spinal injury, respectively.