Simultaneous recordings of electromyography of the external urethral sphincter and bladder pressure during voiding were done for 71 male patients with spinal cord injury. Discordant activities between the anal and the external urethral sphincters were noted in 39 per cent of the patients. The degree of bladder dysfunction was related more to the degree of dyssynergia of the urethral than the anal sphincter. This detrusor-sphincter dyssynergia was found in 67 per cent of our patients regardless of the differences in cystometric patterns and the level of spinal injury. The importance of electromyography of the external urethral sphincter in the diagnosis of neurogenic bladder dysfunction was stressed. The management of detrusor-sphincter dyssynergia is discussed briefly.
We report our experience with radical transurethral resection of the prostate performed on 89 male spinal cord injury subjects. The over-all success rate of modified sphincterotomy was 90 per cent, although there was a 14 per cent recurrence rate with time. Urodynamically, success was characterized by a statistically significant reduction in the degree of detrusor-sphincter dyssynergia, an increase in vesical compliance and a reduction in detrusor hyperreflexia. These results suggest an effect on the distal sphincteric area by the adrenergic system in the genesis of detrusor-sphincter dyssynergia. It is suggested that radical transurethral resection of the prostate exerts this effect via a surgical sympathectomy, while continence is preserved by the activity of the untouched external urethral sphincter.
The genesis of the cystourethrographic appearance of external sphincter spasm in 11 paraplegics with complete lower motor neuron bladders was examined. By the demonstration of its close association with a postural increase in the urethral pressure and catecholamine release, and its responsiveness to alpha-adrenolytic drugs an external sphincter spasm was suggested to be a result of sympathetic dyssynergia in the region of the external sphincter. The smooth muscular component in this region is believed to be a responsible unit of this disorder, since its surgical ablation by means of radical transurethral resection of the prostate uniformly resulted in the relief of sympathetic dyssynergia. The clinical implication of this disorder in the management of vesical dysfunction of the lower motor neuron type is discussed.
To shed further insight into its ever evolving concepts, we studied the activity of the external urethral sphincter in patients with spinal cord injury. Study during the phase of acute spinal shock revealed persistent electromyographic activity in the external urethral sphincter and no activity in the external anal sphincter, suggesting the presence of functional dissociation between the 2 sphincters from the onset of acute spinal injury. The genesis of dissociated activity was discussed by reference to recent experiments on the individual differences in motor neuron and muscle subtypes. Only the external urethral sphincter of chronic paraplegics demonstrated a uniformly increased electromyographic activity after alpha-adrenergic stimulation, while the response in the external anal sphincter was variable. The mechanism of increased response to alpha-adrenergic stimulation in the denervated external urethral sphincter appears to reside either in direct postsynaptic stimulation or recruitment of motor neurons other than the somatic pudendal system, since pre-treatment with competitive muscle relaxant failed to block this increased response in the external urethral sphincter.
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