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.

This is a prospective multicenter phase IIIb randomized double-blind placebo-controlled study, to compare efficacy and tolerance of 3 groups of treatments for epicondylitis.

All patients will be randomized in 3 following parallel treatment groups:

Group A : botulinum toxin + corticoid

Group C : placebo of toxin + corticoid

Group T : botulinum toxin + placebo corticoid

The study will be performed in 4 centers in France, targetting 150 patients. The follow-up of each patient will last 6 months after treatment.

Inclusion Criteria:

• Patient aged between 18 and 60 years;
• Physical disability or not;
• Unilateral lateral epicondylitis more than 3 months, recurrent or not, no response to at least one standard treatment such as: local injection of corticoid, physiotherapy, rest, NSAIDs per os;
• Signed consent obtained;
• Covered by health insurance.

Exclusion Criteria:

• Central nervous system disorders result in spasticity in epicondylitis limb;
• History of severe psychiatric disorder;
• History of myasthenia gravis;
• Pregnant or breastfeeding woman;
• Unable to understand or respond to questions;
• Contraindication to botulinum toxin or corticoid;
• Treatment with botulinum toxin 3 months prior to baseline;
• Anticoagulant theraphy;
• Difficult to follow-up in the study;
• Patient under guardianship, or deprived of liberty by a judicial order.