Further observations of the detrusor electromyogram

Using sophisticated recording equipment and two fine copper wire electrodes introduced through the cystoscope into the bladder muscle of conscious patients at cystoscopy, reproducible electromyographic recordings were obtained from the normal and the neuropathic bladders of a group of patients. By means of simultaneous recording of the electromyographic activity of the rectus abdominis muscle in these patients, it was found that, in general, the variations in electromyographic activity of the normal bladder with filling and voiding are quite independent of abdominal muscle activity. The upper motor neuron bladders by a way of contrast showed continuing electrical activity even at rest and this activity increases with abdominal contraction. Lower motor neuron bladders remain electrically silent at all times including during abdominal muscle contraction. This suggests that the bladder electrodes do not record muscle activity from the abdomen or elsewhere and confirms the validity of the detrusor EMG.