A Phase III Study to Evaluate Efficacy of Botulinum Toxin for Treating Epicondylitis

The study aims to demonstrate that intramuscular injection of botulinum toxin with a paralyzing dose coupled with subcutaneous injection of corticoid has greater efficacy than corticoid injection only or toxin injection only for treating lateral epicondylitis in reducing pain at 6 months. As secondary objectives, the study aims to * demonstrate improvement of quality of patient's life and positive effect on their resuming to professional activities or sportive activities. * evaluate tolerance of treatment by grip strength measurement and adverse event collection.