Improved intramuscular blood flow and normalized metabolism in lateral epicondylitis after botulinum toxin treatment.

Lateral epicondylitis is a common cause of elbow pain, and decreased microcirculation in extensor carpi radialis brevis (ECRB) has recently been suggested to contribute to the symptoms. The purpose of this pilot study was to investigate the treatment response after injection of botulinum toxin type A. Ten patients with unilateral epicondylitis and decreased intramuscular blood flow in ECRB participated. Handgrip, 2-pinch grip and muscle strength during radial deviation and dorsal extension of the wrist were recorded. Perceived pain during contraction was evaluated with the Visual Analogue Scale (VAS) and function in daily activities was assessed using the Disability of Arm, Shoulder and Hand instrument (DASH) and the Canadian Occupational Performance Measure instrument (COPM). Intramuscular blood flow was recorded by laser Doppler flowmetry, and microdialysis was used to analyze muscle metabolism. The difference in intramuscular blood flow between the control and the affected side had decreased 3 and 12 months after treatment (P=0.03). Lactate concentration at the 12-month follow-up had decreased (P=0.02); perceived pain was reduced and function in daily activities had improved. Injection of botulinum toxin is an alternative treatment for epicondylitis. Symptom relief may be due to enhanced microcirculation causing an aerobic metabolism.