[Manometric factors associated with recurrence in botulinum toxin treatment for chronic anal fissure]

To evaluate the effectiveness of botulinum toxin in the treatment of chronic anal fissure after long-term follow-up and establish the manometric factors related to recurrence.

We performed a prospective study in 50 consecutive patients with chronic anal fissure who were treated with 25 U botulinum toxin injected into the internal sphincter. Clinical and manometric parameters were recorded until the fourth year of follow-up.

There was a tendency to progressive recurrence over time (54% at 4 years) associated with manometric factors indicating hyperexcitability of the internal anal sphincter (persistently elevated mean resting pressure, percentage of time with slow waves, and number of patients or percentage of time with ultra-slow waves after treatment).

Treatment of chronic anal fissure with botulinum toxin leads to long-term cure in less than 50% of patients. In patients with manometric factors related to recurrence, this treatment is insufficient for definitive cure.