Marcelo Bordalo-Rodrigues MD, Presenter: Nothing to Disclose

Conrado Furtado A. Cavalcanti PhD, Abstract Co-Author: Nothing to Disclose

Rafael Burgomeister Lourenco MD, Abstract Co-Author: Nothing to Disclose

Giovanni Guido Cerri MD, PhD, Abstract Co-Author: Nothing to Disclose

Radial tunnel syndrome is caused by entrapment of the posterior interosseous nerve at the elbow and is manifested by forearm pain, without motor deficits. The clinical diagnosis may be difficult, considering that radial tunnel syndrome can be associated with or masquerade as lateral epicondylitis. It has been shown that the most reliable radiologic sign of radial tunnel syndrome is muscle denervation along the posterior interosseous nerve distribution, most commonly within the supinator muscle. Since ultrasound (US) can show muscle fatty atrophy, we sought to study the presence of supinator muscle atrophy by US in patients with clinically suspected lateral epicondylitis.

In a prospective study, 43 patients were studied (19 women, 24 men, mean age 31 years). All patients had clinical diagnosis of lateral epicondylitis. All US examinations of the elbows were performed by a single musculoskeletal radiologist with particular attention to echogenicity and morphologic alterations of the posterior interosseous nerve, fatty atrophy of the supinator muscle (depicted as hiperechogenicity and thinning of the muscle, as compared to the contralateral asymptomatic side), and echogenicity alterations at the origin of the common extyensor tendons, suggesting an associated or alternative diagnosis of lateral epicondylitis.

Supinator muscle atrophy was found in 13.9% (6/43) of the cases. Diagnosis of lateral epicondylitis was suggested in 79%(34/43) of the patients. In 6.9% (3/43) there was an association of supinator muscle atrophy and lateral epicondylitis. No US alterations were found in the posterior interosseous nerve.

Our data indicates that radial tunnel syndrome must be considered in the differential diagnosis of patients with clinical suspicion of lateral epicondylitis and, therefore, supinator muscle evaluation should be included in the ultrasound examination of the elbow in patients with this specific clinical condition.

Radial Tunnel Syndrome is a differential diagnosis for lateral epicondylitis and should be considered in resistant tennis elbow. The presence of supinator muscle atrophy may suggest this diagnosis.

Bordalo-Rodrigues, M, Cavalcanti, C, Lourenco, R, Cerri, G, Supinator Muscle Atrophy Evaluation with Ultrasound in Patients with Clinically Suspected Lateral Epicondylitis.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8014774.html