Efficacy of Sacral Nerve Modulation in Severe Refractory Constipation

Inclusion Criteria: * Age ≥ 18 years old * Constipation defined by at least two of the following criteria : * Frequency of 2 stools or less per week * Severe outlet constipation, i.e. need to use digital extraction or enemas more than 25% of time * Sensation of incomplete evacuation more than 25% of time * Refractory constipation since at least 1 year to medical treatment (drug treatment and/or biofeedback) conducted in the centre (failure or intolerance to laxative osmotic treatments, stimulants, and prucalopride) for which surgery is discussed * Patients supported in the centre for at least 3 months before inclusion * Patients having social security system * Patients having read and signed informed consent form Exclusion Criteria: * Constipation secondary to ano-rectal malformation, surgical sequel, colorectal or anal organic lesions, or pelvi-perineal static disorder indicated for surgical treatment * Constipation secondary to neurological pathology and/or concomitant treatments intake (opiates, anticholinergic agents) * Partial colectomy history * Patients in whom implantation of stimulating electrode is impossible due to anatomical reasons (e.g. sacral agenesis) * Pregnant female patients or with childbearing potential without adequate contraceptive barrier (oestrogen-progesterone contraceptives or intra-uterine device) * Skin disease associated with a risk of infection - in the opinion of the investigator * Patient with pacemaker or defibrillator * Patient exp…