Perineal electromyographic patterns in urge incontinence.

The EMG patterns of anal sphincter and periurethral striated musculature were analyzed in 55 women with urge incontinence during cystometry. Six had a sensory urge and 49 a motor urge incontinence. In 18 cases the unstable bladder contractions were accompanied by an intense EMG activation and in 31 cases by a decrease of perineal activity. During bladder filling a progressive decline of activity was found in 9 cases and an irregular EMG pattern and urethral pressure in 18 cases. Five patients had abnormal EMG action potentials while 16 out of 39 patients had an abnormal evoked sphincter reaction. Although the EMG of the perineal muscles during bladder filling is often abnormal in women with urge incontinence, it does not give any additional information on the causes of the urethral and bladder instability.