Sphincterotomy and the treatment of detrusor-sphincter dyssynergia: current status,future prospects

STUDY DESIGN: Literature review of current treatment options for detrusor-sphincter dyssynergia (DSD) in spinal cord injury. OBJECTIVES: To review the outcomes and complications associated with external sphincterotomy and to summarise the results and complications of alternative treatment options for detrusor-sphincter dyssynergia in spinal cord injury. In addition, we propose a potential alternative future drug treatment for external sphincter dyssynergia based upon recent research on the neuropharmacology of the external urethral sphincter. SETTING: The National Spinal Injuries Centre, Stoke Mandeville Hospital, Aylesbury, UK. METHODS: Medline search from 1966 to 2002 using the words 'external sphincterotomy', 'detrusor-sphincter dyssynergia' and 'neurogenic bladder combined with surgery'. RESULTS: While external sphincterotomy is an effective treatment for DSD, a significant number of men following this procedure continue to have high intrarenal pressures, recurrent urinary infection or troublesome autonomic dysreflexia and a worryingly high proportion demonstrate persistently raised leak point pressures, putting them at subsequent risk of renal damage. Alternative treatments for external sphincter dyssynergia include urethral stents and balloon dilatation, both of which are effective. However, over the long term stents can undergo encrustation and there remains a definite risk of stent migration necessitating stent removal or replacement. Balloon dilatation of the external sphincter is associated with a risk of subsequent stricture formation. Intraurethral Botulinum A toxin seems to be effective though there have been no large randomised studies comparing it against placebo. However, it is not a durable treatment option and it has not found a common place in the treatment of DSD.There is now a considerable amount of experimental data from both animal and human studies to suggest that nitric oxide (NO) is an important physiological inhibitory neurotransmitter in the urethral sphincter, mediating relaxation of the external urethral sphincter. The potential role of sphincter NO augmentation for treatment of DSD is discussed. CONCLUSION: External sphincterotomy remains the mainstay of treatment for urodynamically significant detrusor-sphincter dyssynergia, but in recent years a number of effective, alternative treatment options have become available. While at present there is no effective systemic drug treatment, recent research into external sphincter neuropharmacology suggests that systemic or topical augmentation of external sphincter NO may provide an effective method for lowering sphincter pressure.