Myofascial pains are frequently found during the clinical examination of the patients presenting a painful chronic syndrome of the pelvis or the perineum. If the physiopathology of this component of the pain characterized by triggerpoints found in the clinical examination, remains uncertain; its coverage contributes to the improvement of the global pain of the patient. The physiotherapy can be useful but when it is not useful, we proposed injections of triggerpoints by local anesthetics. The injections of botulinum toxin on these triggerpoints have a legitimacy (action on the muscular cramp and action on the afferent fibers) but are they superior to the injections of local anesthetics of triggerpoints? The literature remains poor on the subject, justifying this randomized double-blind protocol comparing the efficacy of the botulinum toxin associated with a local anesthetic versus local anesthetic alone with a main criterion of evaluation in 2 months and a monthly follow-up as long as the patient remains improved and maximum in 6 months.

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