The objective of this study is to evaluate the efficacy of ultrasound guided corticosteroid injection in reducing symptoms caused by carpal tunnel syndrome.

Corticosteroid injection is routinely given for treating carpal tunnel syndrome. The objective of this study is to evaluate the efficacy of ultrasound guided corticosteroid injection in reducing symptoms caused by carpal tunnel syndrome.

In this randomised clinical trial, 50 patients with both a clinical and electromyographic diagnosis of mild to moderate carpal tunnel syndrome will be recruited from the Centre Hospitalier Universitaire de Sherbrooke (CHUS). Subjects will be randomised to ultrasound guided or blind injection groups. All subjects will receive 40 mg of methylprednisolone. The primary outcome will be the Boston Carpal Tunnel Syndrome Questionnaire - Symptom Severity Scale at baseline and 3 months post injection. Both subjects and assessors will be blinded.

Inclusion Criteria:

• Aged 18 to 65
• Understanding written and spoken french
• Diagnostic of carpal tunnel syndrome : Classic of probable based on the Katz Hand Diagram and mild to moderate based on the electrodiagnosis studies

Exclusion Criteria:

• Carpal tunnel injection in the last 6 months
• Constant symptoms in medial nerve area
• Thenar eminence atrophy
• Absolute contraindication to corticosteroid injection : infective arthritis, bacterial endocarditis, local cellulitis of skin infection, coagulopathy, corticosteroid or latex allergy
• Secondary diagnosis based on the ultrasound : arthrosynovial cyst, flexor tenosynovitis, ganglion
• Known cognitive disorder
• Anticoagulant therapy
• Diseases known to cause carpal tunnel syndrome : Diabetes mellitus, hypothyroidism, connective tissue disease, rheumatic disease and moderate or severe chronic renal impairment
• Radiculopathy
• Polyneuropathy
• Pregnancy
• Ancient ipsilateral wrist fracture
• Ancient ipsilateral wrist surgery