Background and aims: Autonomic dysreflexia is a common and potentially dangerous response in patients with spinal cord injury at T6 or above. Acute blood pressure elevation may be precipitated by rectosigmoid distention and anal manipulation. Topical anesthetics are widely recommended to minimize the incidence and severity of autonomic dysreflexia, although no scientific evidence supports or refutes this practice. This study tested whether topical lidocaine would prevent or limit anorectal procedure-associated autonomic dysreflexia.
Patients and methods: We enrolled patients with chronic, complete spinal cord injury scheduled for anoscopy and/or flexible sigmoidoscopy. In a double-blind fashion they were randomized to receive either 2% lidocaine jelly (n = 18) or nonmedicated lubricant (control; n = 32) just prior to the procedure. We measured blood pressure before, during, and after procedures.
Results: Mean maximal systolic blood pressure increased 35 +/- 25 mmHg in the lidocaine group vs. 45 +/- 30 mmHg in the control group (NS). However, there was a significant difference between anoscopic procedures and flexible sigmoidoscopies without anoscopy (49 +/- 29 vs. 25 +/- 20 mmHg).
Conclusion: Topical lidocaine did not significantly limit or prevent autonomic dysreflexia in susceptible patients. Both anoscopy and flexible sigmoidoscopy caused significant blood pressure elevation. Anoscopy, which involves stretching of the anal sphincters, was a more potent stimulus for autonomic dysreflexia than flexible sigmoidoscopy, which involves gaseous distention of the rectosigmoid. Anal sphincter stretch and rectosigmoid distention, rather than a mucosal stimulus, are likely nociceptive triggers for procedure-associated autonomic dysreflexia.