Between October 2013 and January 2014, 10 patients diagnosed with chronic anal fissure at the Pelvic Floor Centre - University Hospital of Malmo, Sweden were treated with percutaneous tibial nerve stimulation. Ethical clearance to use the results in a scientific setting was obtained from the ethics committee of the University of Lund, Sweden (Dnr 2016/998). Pre-treatment evaluation included detailed medical history and anorectal examination. All patients presented with pain and/or bleeding and the presence of a chronic anal fissure was confirmed by clinical examination.

Patients were included in the study if they were older than 18 years and had symptoms of chronic anal fissure for at least 6 months. All patients must have been on high fiber diet and stool softeners and in addition failed all conservative pharmacological treatment with topical application of anaesthetic creams, muscle relaxants (nitroglycerin or diltiazem) and/or botulinum toxin injection. We excluded patients with pregnancy, pacemaker device, low molecular heparin or warfarin treatment, neurological disease, inflammatory bowel disease and radiation proctitis. The Visual Analog Scale (VAS), St. Marks Incontinence Score, Wexner´s Constipation Score, Brief Pain Inventory - Short form (BPI-SF), symptom relief, bleeding and mucosal fissure healing were evaluated before and after treatment. VAS and BPI-SF were used to measure subjective pain characteristics and symptoms of patients at baseline, after two weeks (end of treatment), three months and then after one, two and three years. St. Marks Score and Wexner´s Constipation Score were evaluated in the same way though only up to one year after completion of treatment. The patients were given percutaneous tibial nerve stimulation after obtaining informed consent. The procedure was performed by two experienced pelvic floor therapists. Patients retained their high fiber diet and stool softeners during the procedure. Percutaneous tibial nerve stimulation was performed by using the Urgent PC Neuromodulation System ® (Uroplasty, Holland) on an outpatient basis. A stimulator provides electrical current with a fixed pulse frequency of 20Hz, pulse width 200 µ seconds and current setting between 0.5 and 9 mA (amplitude). A surface electrode was placed at the medial arch of the midfoot and a needle electrode was inserted through the skin posterior to the medial malleolus and advanced towards the posterior tibial nerve. Stimulation was gradually increased until a tingling sensation was perceived in the foot, or a motor flexor response was observed at the big toe. All patients received the treatment for 30 minutes 5 days a week, during 2 consecutive weeks. The clinical state of the fissure was evaluated before and after the last treatment session as well at three months and one year (though at the 3 month follow up one patient declined clinical examination since he felt completely symptom free). The fissure wound was characterized as not healed, partially healed when the healing process was visible but not totally complete and healed when no sign of the fissure was visible. At two and three years all patients were contacted by phone, and those who had symptoms where chronic anal fissure could not be ruled out underwent a clinical examination.

Statistical analyses:

The clinical outcome i.e. none healed, partially or totally healed fissure was analysed in relation to VAS, mean of St. Marks Incontinence Score and sum of Wexners's Constipation Score. These questions were chosen due to their clinical importance and high response rate. All analyses were calculated with descriptive statistics due to the few amount of patients. All analyses were performed with SPSS 22.