Outlet type constipation in Parkinson's disease: results of botulinum toxin treatment

Background: Constipation is one of the most common autonomic dysfunctions observed in Parkinson's disease. Aim: To investigate the efficacy of injections of botulinum toxin in improving rectal emptying in these patients. Methods: Eighteen Parkinson's disease patients with outlet constipation were included in the study. The patients were treated with type A botulinum toxin, injected into two sites on either side of the puborectalis muscle under ultrasonographic guidance. Results: Symptomatic improvement was noted in 10 patients, at 2 months evaluation. In these subjects, anorectal manometry demonstrated decreased tone during straining from 96.2 +/- 17.1 to 45.9 +/- 16.2 mmHg at 1 month evaluation (P = 0.00001) and to 56.1 +/- 10.7 mmHg at 2 months (P = 0.00001). Pressure during straining was lower than resting anal pressure at the same times in all patients. Defecography after the treatment showed improvement in anorectal angle during straining, which increased from 99.1 +/- 8.4 degrees to 121.7 +/- 12.7 degrees (P = 0.00001) at 2 months. Conclusions: Botulinum toxin injections may be a useful treatment for Parkinson's disease patients affected by outlet-obstruction constipation. The treatment is safe and simple. However, because the effects of the toxin wear off within 3 months of administration, repeated injections could be necessary to maintain the clinical improvement.