Isolated Musculocutaneous Neuropathy In A College Baseball Pitcher

HISTORY: A 21-year-old college baseball pitcher developed persistent right upper extremity paresthesia and weakness of elbow flexion after pitching in a game. He did continue to pitch for 3 days after onset. He presented to the athletic trainer after continued diminished sensation to the lateral aspect of the proximal forearm and weakness with pitching, bicep curls, and other movements requiring elbow flexion. PHYSICAL EXAMINATION: Right upper extremity decreased strength with elbow flexion when compared to the left. Diminished sensation to the lateral forearm. No atrophy. Spurling’s negative. Cervical ROM was WNL. Adsons test was negative bilaterally. Strength testing for GH abduction was 5/5, ER 4/5, and IR 5/5 all without pain. Negative Speed’s, O’briens, and biceps load 2 testing. DIFFERENTIAL DIAGNOSIS: 1. Thoracic outlet syndrome2. Cervical radiculopathy3. Brachial plexopathy4. Rotator cuff injury TEST AND RESULTS: EMG/NCS RUE: Evaluation of the right lateral antebrachial cutaneous sensory nerve showed no response. The left lateral antebrachial cutaneous sensory nerve was normal. The Right median motor, the right ulnar motor, the right median D2 sensory, the right ulnar sensory, and the right median/radial comparison - sensory nerves were unremarkable. Right biceps increased insertion activity and moderately increased spontaneous activity. There is electrodiagnostic evidence suggestive of an acute axonometric injury to the right musculocutaneous nerve, subsequently affect the lateral antebrachial cutaneous nerve as well. There were numerous voluntary motor unit presents in the right biceps, which suggests an incomplete injury and the potential for clinical recovery. No electrodiagnostic evidence of a right upper extremity plexopathy or radiculopathy, and no electrodiagnostic evidence of any additional right upper extremity mononeuropathies. FINAL/WORKING DIAGNOSIS: Right musculocutaneous nerve injury. TREATMENT AND OUTCOMES: 1. Relative rest, no pitching 2. Weighted bicep curls with supinated and pronated grips for 4 weeks and focus on progressive overload.3. After 3 weeks of treatment sensation of the lateral forearm improved and returned to baseline. After 4 weeks of treatment RUE flexion strength improved but has not returned to baseline. Has not returned to pitching.