Acute suppression of idiopathic detrusor instability with magnetic stimulation of the sacral nerve roots

Objective To assess the effect of magnetic stimulation of the S3 nerve root on unstable contractions in patients with idiopathic detrusor instability, Patients and methods Twelve patients with idiopathic instability were studied. The S3 nerve root was localized by mapping the response of the toe flexor muscles and anal sphincter to magnetic stimulation at different sites. Unstable contractions were provoked by rapidly infusing saline into the bladder and the effect of magnetic stimulation of S3 on contractions was assessed. Results Magnetic stimulation relieved the sensation of urinary urgency and reduced the duration and amplitude of provoked contractions in all patients. Stimulation reduced the area under the pressure/time curve by 80 - 98%. In some patients there was a short-lived residual suppressive effect lasting up to 90 s. Conclusions Magnetic stimulation of S3 acutely abolishes unstable contractions in patients with idiopathic detrusor instability.