Mechanisms of Action on Rectal Motricity of Intrarectal Botulinum Toxin Injections

Inclusion Criteria: * Active or predominantly active fecal incontinence with failure of 1st-line conservative treatments (normalization of transit, perineal re-education) * Impairment of quality of life at investigator's discretion * Patients at least 18 years of age * Patients who have read and understood the information letter and signed the consent form * Patients affiliated to the French Social Security system * Women of childbearing age using effective contraception (Cf. CTFG) (estro- progestins or intrauterine device or tubal ligation) for at least 1 month and a negative B-HCG urine pregnancy test at inclusion and for the duration of the study. * Postmenopausal women: confirmatory diagnosis (non-medically induced amenorrhea for at least 12 months prior to inclusion visit) Exclusion Criteria: General * Pregnant women, women in labor, breastfeeding women, or women without proven contraception * Patient deprived of liberty by administrative or judicial decision, or protected adult (under guardianship or trusteeship) * Exclusive passive fecal incontinence * Patient suffering from constipation (Rome IV criteria) * Patient with an evolving inflammatory or cancerous digestive pathology * Previous rectal surgery * Person participating in another research protocol or having participated in another research protocol in the 4 weeks preceding the inclusion visit Linked to botulinum toxin injections * Hypersensitivity to botulinum toxin or to one of the excipients (human albumin, sodium chloride) * Neuromuscular junction pathology (myasthenia, Lambert-Eaton syndrome, etc.) * Presence of infection at injection site(s) * General anesthesia less than one month ago * Association with aminoglycosides and anti-cholinesterase agents (risk of increased toxin effects) * History of neurogenic damage such as polyradiculoneuritis * History of dysphagia with esophageal or neurological stasis, swallowing disorders, inhalation pneumonitis * Botulinum toxin injections in the 3 months preceding the study * Clinical anal examination suggestive of anorectal abscess * Recent history (\<12 months) of myocardial infarction and/or rhythm disorders not reduced by appropriate treatment * Peripheral motor neuropathies (such as amyotrophic lateral sclerosis or motor neuropathy) and underlying neurological disorders * Current treatment with anticoagulants or anti-aggregants or haemostasis disorders according to recommendations (SFED). When patients are on anticoagulant or anti-aggregant therapy, the type of injections to be performed depends on the type of anticoagulation and the patient's thrombo-embolic risk: * Patients on anticoagulant or anti-aggregant therapy with a major thrombo-embolic risk will not be included. * Patients on anticoagulant or anti-aggregant therapy with a moderate or low thrombo-embolic risk may be included. If patients are taking a vitamin K antagonist, treatment will be continued provided that the INR is within the usual range of 2 to 3 (GETED, HAS, 2008). If patients are taking anti-aggregants, these can be continued (SFED, HAS, 2012). If patients are taking new oral anticoagulants, they should take a short break and not take the AOD the evening before or the morning of the injections (GIHP, 2015). Linked to rectosigmoidoscopy * Local pathology preventing colonoscopy (anal stenosis) * Allergy or hypersensitivity to silicone and/or latex Linked to laxatives * Contraindication to DULCOLAX® 5 mg, gastro-resistant coated tablet * Contraindication to XIMEPEG®, powder for oral solution Linked to high-resolution manometry * Clinically diagnosed intestinal obstruction * Severe coagulopathy or oral anticoagulants * Cardiac disorders for which vagal stimulation is poorly tolerated