What is the role of botulinum toxin (BTX) injections for pain management in rectal disorders?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Other miscellaneous painful disorders have responded to BTX-A treatment as evidenced by a randomized, controlled study that suggests BTX-A can be effective in reducing pain after hemorrhoidectomy. [93] . Another published review suggests that BTX may be effective in the management of severe anorectal pain. [94]

The maximum resting pressure in the anal canal is markedly increased after hemorrhoidectomy, most likely due to postoperative pain, which is the most difficult early management problem after hemorrhoidectomy.

Patti et al compared the effects of intrasphincter BTX-A injections with application of glyceryl trinitrate ointment after hemorrhoidectomy for improving wound healing and reducing postoperative pain at rest or during defecation. [95] Thirty patients with hemorrhoids were randomized into 2 groups. One group received an injection containing 20 U of BTX-A, whereas the other group received application of 300 mg of 0.2% glyceryl trinitrate ointment 3 times daily for 30 days. Anorectal manometry was performed preoperatively and then at 5 days and 40 days following hemorrhoidectomy.

Five days after hemorrhoidectomy, maximum resting pressure was significantly reduced compared with baseline values in both groups; however, postoperative pain at rest showed a significant reduction in the BTX-A group compared with the glyceryl trinitrate group; pain during defecation and time of healing were similar. Adverse effects, such as headaches, were observed only in the glyceryl trinitrate group. At 40 days posthemorrhoidectomy, the maximum resting pressure values in the glyceryl trinitrate group were similar to those obtained preoperatively. However, the maximum resting pressure values remained decreased in the BT-XA group. These findings support the application of a single intrasphincter injection of BTX-A for more effective reduction of early postoperative pain at rest, although not necessarily during defecation. BTX-A is safer and has less side effects than repeated applications of glyceryl trinitrate.

However, Singh et al looked at 32 patients undergoing haemorrhoidectomy in a prospective randomized controlled trial. [96] Routine postoperative care included metronidazole and bupivacaine. Patients were also randomized and given an intersphincteric injection of either placebo or BTX-A (150 U). A linear analogue score (VAS) was used to assess postoperative pain. The primary endpoint was reduction in postoperative pain. No significant effect on overall or maximal pain scores was noted. Median time for return to normal activities did not differ significantly between groups. BTX-A reduced anal spasm but failed to demonstrate any significant effect on postoperative pain.

Thrombosed external hemorrhoids are a frequent anorectal emergency. They are associated with swelling and intense pain. Patti et al randomized 30 patients with thrombosed external hemorrhoids who refused surgical operation into 2 groups. [97] Patients received an intrasphincteric injection of either 0.6 mL saline or 0.6 mL of a solution containing 30 U of BTX-A. Anorectal manometry was performed before treatment and 5 days afterwards. After 5 days of treatment, the maximum resting pressure fell in both groups but was significantly lower in the BTX group (P = 0.004). Pain intensity was significantly reduced within 24 hours of BTX-A treatment (P < 0.001) but only after 1 week in the placebo group (P = 0.019). A single injection of BTX into the anal sphincter seems to be effective in rapidly controlling the pain associated with thrombosed external hemorrhoids and could represent an effective conservative treatment for this condition.

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