Summary Pronator Syndrome is a compressive neuropathy of the median nerve at the level of the elbow. Diagnosis is made clinically with pain at the proximal volar forearm, sensory changes over the palmar cutaneous branch, and positive Tinel's over the proximal volar forearm. Treatment involves a prolonged nonoperative course, and rarely, surgical decompression. Epidemiology Incidence rare < 1 per 100,000 annually Demographics female > male common in 5th decade Risk factors associated with well-developed forearm muscles (e.g. weight lifters) Etiology Pathoanatomy 5 potential sites of entrapment include supracondylar process login to view 1 more bullet ligament of Struthers login to view 2 more bullets bicipital aponeurosis (a.k.a. lacertus fibrosus) between ulnar and humeral heads of pronator teres login to view 1 more bullet FDS aponeurotic arch Associated conditions commonly associated with medial epicondylitis Presentation Symptoms paresthesias in thumb, index, middle finger and radial half of ring finger as seen in carpal tunnel syndrome in pronator syndrome paresthesias often made worse with repetitive pronosupination should have characteristics differentiating from carpal tunnel syndrome (CTS) aching pain over proximal volar forearm sensory disturbances over the distribution of palmar cutaneous branch of the median nerve (palm of hand) login to view 1 more bullet lack of night symptoms Physical exam provocative tests are specific for different sites of entrapment positive Tinel sign in the proximal anterior forearm but no Tinel sign at wrist nor provocative symptoms with wrist flexion as would be seen in CTS resisted elbow flexion with forearm supination (compression at bicipital aponeurosis) resisted forearm pronation with elbow extended (compression at two heads of pronator teres) resisted contraction of FDS to middle finger (compression at FDS fibrous arch) possible coexisting medial epicondylitis Imaging Radiographs recommended views elbow films are mandatory findings may see supracondylar process Studies EMG and NCV may be helpful if positive but are usually inconclusive may exclude other sites of nerve compression or identify double-crush syndrome Differential AIN compressive neuropathy Carpal tunnel syndrome Pronator teres strain Treatment Nonoperative rest, splinting, and NSAIDS for 3-6 months indications login to view 1 more bullet technique login to view 1 more bullet Operative surgical decompression of median nerve indications login to view 1 more bullet technique login to view 1 more bullet outcomes login to view 2 more bullets