EVALUATION OF GRACILIS MUSCLE TRANSPOSITION FOR FECAL INCONTINENCE WITH MAGNETIC-RESONANCE-IMAGING

Ten consecutive patients with incapacitating fecal incontinence were t reated with 'anal dynamic graciloplasty' (transposition of the gracili s muscle around the anal canal and implantation of intramuscular elect rodes connected with an implanted pulse generator, 6 weeks later) to a chieve continence. We measured the gracilis muscle diameter immediatel y after transposition and before implantation of the stimulation devic e. It was found that gracilis diameter decreased from 12 (5 days after transposition) to 8 mm, 6 weeks later (mean decrease: 4 mm (95% confi dence interval 3.6), n = 10, P < 0.05). In addition, morphology demons trated a decrease of both Type I and Type II muscle fiber diameter and an increase in endomysial collagen. Despite this decrease in muscle ( and muscle fiber) diameter, electrical stimulation of the transposed g racilis muscle increased the pressure into the anal canal from 37 to 5 5 mmHg (mean increase: 17 mmHg (95% confidence interval 6.29), P < 0.0 5). Fecal continence was achieved in seven (70%) of these patients. Fu rther analysis revealed no correlations between reduction of the graci lis muscle diameter before implantation of the stimulation device and clinical outcome in terms of achieved continence and/or anal canal pre ssures. MRI is an excellent method to demonstrate the shape of gracili s muscle after transposition. However, the size of transposed gracilis muscle is not associated with the functional outcome.