Anorectal surgery is a type of surgery that can cause anal pain, particularly in the context of hemorrhoid surgery or anal fissure surgery. Generally, the period of discomfort related to the pain lasts about two weeks. There is a nerve (the vagus nerve) whose stimulation via a probe placed in the ear can reduce stress and chronic pain. Its ease of use makes it a promising tool for treating pain. Vagal auricular stimulation could be an interesting option in the management of postoperative pain of the anus and rectum. Its efficacy or feasibility in this context has never been evaluated.

The aim of this study is to evaluate the feasibility in this context and to assess the extend of pain reduction associated with perioperative nerve vagus stimulation by a medical device (Transcutaneous Electrical Nerve Stimulator (TENS ECO Plus)). It is offered to adult patients undergoing transanal anal or rectal surgery on an outpatient or inpatient basis as part of a scheduled procedure.

Patients to be included in the study are selected during the initial pre-operative consultation with the surgeon. Once the surgical indication is confirmed and the patient fulfills the study eligibility criteria, the investigator provides them with oral information about the study. The patient is also given an information sheet (written in language understandable to the patient) and a consent form.

During this initial visit, demographic data and information regarding the surgical indication are collected.

Stimulation begins two days before surgery (twice daily), followed by stimulation on the morning of surgery, one hour before arrival in the operating room. Successful completion of the stimulation, as well as any complications, are recorded in the patient diary.

On the day of surgery (day 0), data concerning the procedure and the maximum visual analogue scale (VAS) are collected in the recovery room. Analgesic consumption is also recorded.

On the evening of the procedure, stimulation is performed and adherence is recorded.

Maximum and mean VAS are collected on postoperative day 1 and then daily in the patient diary for 15 days.

Vagus nerve stimulation is performed morning and evening for 15 days. VAS scores, adherence, analgesic consumption, the date of the first bowel movement and its painfulness, as well as any complications related to the stimulation are noted in the patient diary. On day 3 (+/- 2 days) after the procedure, and at the end of the 15-day postoperative period, the patient will be contacted by phone or text message by the investigator team to remind them to complete the notebook.

On day 30 (+/- 5 days), the patient returns for a follow-up visit. The patient diary and equipment are collected. Complications are recorded, as well as quality of life during the postoperative month (SF-36 form).

For patients, the expected benefits are significant, as postoperative quality of life is expected to improve through reduced pain. Furthermore, decreasing the use of step II and III analgesics should shorten the recovery period and promote better overall recovery.

Inclusion Criteria:

• Adult patient
• Underwent anal or rectal surgery via the transanal route
• Managed on an outpatient basis or in conventional hospitalization
• Having signed a consent to participate in the study

Exclusion Criteria:

• Patient operated on as an emergency
• Rectal surgery via abdominal approach or requiring an abdominal approach during the procedure
• Known epileptic patient
• Patient with a pacemaker
• Patient refusing to participate in the study
• Pregnant, breastfeeding, or laboring woman
• Patient not affiliated with a social security scheme
• Person deprived of liberty by judicial or administrative decision
• Person subject to compulsory psychiatric care - Any contraindication mentioned in the instructions for use of the medical device under investigation

Exclusion Criteria:

• Unscheduled conversion from the transanal route to the abdominal route during surgery