Chronic anal fissure rarely heals spontaneously. About 50% heal on administration om topical muscle relaxants (e.g. diltiazem) and/or injection of Botulinum toxin, but for the remainder of patients surgery (with lateral internal sphincterotomy or fissurectomy) with subsequent risks of anal incontinence has been the golden standard. Treatment with PTNS (percutaneous tibial nerve stimulation) has been showed to produce healing of chronic anal fissures not responding to topical treatment, thus avoiding the risk for debilitating anal incontinence.

This study will prospectively include 52 patients with chronic anal fissure that have received topical treatment and stool softeners and have all been evaluated by experienced proctological surgeons. The treatment will be given for 10 consecutive work days and then evaluated at 3 and 12 months. If the patients symptoms are unimproved at 3 months alternative treatments will be offered.

Inclusion Criteria:

• Verified anal fissure (Clinical assessement by experienced proctological surgeon)
• Full conservative treatment has been given

Exclusion Criteria:

• Inflammatory bowel disease
• Fistula and/or anal abscess
• Patients with compromised immunity
• Pregnancy
• Treatment with anti-coagulants (not aspirin)
• Previous irradiation towards pelvic floor
• Pacemaker or implanted defibrillator

No intention to make individual participant data available to other researchers