Multicenter Randomized Double-blind Study Evaluating the Effects of Botulinum Toxin A Associated With ropivacaïne Versus ropivacaïne Alone in the Treatment of the Myofascial Pelviperineal Pain

Inclusion Criteria: * Age \> 18 years * Patient presenting a "dysfunctional" pain of the pelvis or the perineum (without lesional pathology justifying a specific treatment) by an endopelvic touch * Pain evolving since at least 6 months and persisting in spite of the analgesic treatments and the physiotherapy * Patient presenting to the clinical examination one or several active triggerpoints found on the internal obturating muscles and/or elevators of the anus, with a maximum of 10 triggerpoints on the whole body. * Patient presenting an average of the maximal pains of the week before the inclusion superior or equal to 4 and inferior or equal to 9/10 (evaluation of the daily maximal pain on a digital scale from 0 to 10) * Signed informed consent * Subjects affiliated with an appropriate social security system Exclusion Criteria: * Patients with bleeding risk and anticoagulant therapy * Intolerance of botulinum toxin A, ropivacaïne and nitrous oxide * Injection of botulinum toxin in any place whatsoever in the previous 3 months * Pregnancy and breast feeding * Antibiotic treatment by aminoglycosides * Recent anti-inflammatory treatment * Severe myasthenia * Lambert-Eaton syndrome * Patients with neurological disorders, dysphagia, food choking or inhalation pneumonia * Beck score \> 16 * Patients having an average of the maximal pains of the previous week lower than 4