Botulinum toxin in the treatment of outlet obstruction constipation causedby puborectalis syndrome

PURPOSE: Puborectalis syndrome has been difficult to treat. We investigated the efficacy of botulinum toxin in treating patients with puborectalis syn drome who had previously failed to respond to electromyographic biofeedback sessions and who refused to use anal dilators. METHODS: Of a group of 50 p atients with chronic outlet obstruction constipation, four patients with pu borectalis syndrome were included in the study. The patients were studied u sing anorectal manometry, defecography, and electromyography and then treat ed with 30 units of Type A botulinum toxin, injected into two sites on eith er side of the puborectalis muscle, under ultrasonographic guidance. RESULT S: One patient was lost to follow-up. After treatment in other patients, th e frequency of natural bowel movements increased from zero to six per meek and laxatives were needed by only one patient. Anorectal manometry demonstr ated decreased tone during straining from (mean +/- standard deviation) 96. 2 +/- 12 mmHg to 42.5 +/- 13 mmHg at four weeks (P = 0.003) and 63.2 +/- 22 mmHg at eight weeks (P = 0.003). Defecography performed eight weeks after treatment showed improvement in the anorectal angle, which increased from 9 4 +/- 11 degrees to 114 +/- 13 degrees (P = 0.01), and evacuation of barium paste. Electromyography demonstrated mild paradoxical contraction. However , 16 weeks after treatment one of these three patients suffered symptomatic recurrence. This patient was re-treated with 50 units of toxin; eight mont hs later he required a further 60 units. Seven months after the last inject ion he reported normal daily bowel movements without the use of laxatives. CONCLUSIONS: Botulinum toxin injection should be considered as a simple the rapeutic approach in patients with puborectalis syndrome. The use of higher dosage and a more precise method of toxin injections under transrectal ult rasonography account for the long-term higher success rate. However, becaus e the effects of the toxin wear off within three months of administration, repeated injections could be necessary to maintain the clinical improvement .