SHOULDER PAIN AND WEAKNESS - ADVENTURE RACING

Abstract

HISTORY A 35 year-old right-handed elite adventure racer sustained a left shoulder injury while mountain biking when he collided into a tree with his left anterior shoulder. Three weeks prior he had bruised his left face and strained his left neck when he collided with a tree. The shoulder/neck pain associated with both incidents was mild and resolved within several days. Two weeks following the second tree collision, the patient developed severe left shoulder pain, weakness, and dysesthesias involving the proximal upper extremity immediately following a swimming session. Over the next two week, opiate medication was necessary to control the pain and provide satisfactory sleep. Four weeks later he presented to this clinic with no significant improvement in his symptoms. He denied parasthesias or weakness in the other limbs. He was otherwise in good health. PHYSICAL EXAMINATION Examination in our clinic revealed mild atrophy of the left supraspinatus and infraspinatus muscles with normal active external rotation. Testing of the other muscles in the upper limbs tested revealed normal 5/5 strength. Sensation was intact bilaterally to light touch and pin prick and muscle stretch reflexes were 2+/4 and symmetric ROM of the upper extremities. Manual muscle testing was 4/5 for left shoulder abduction and 3/5 for left shoulder. Palpation revealed no tenderness in the left upper extremity, shoulder girdle or cervical paraspinal muscles. Spurling's test was significant for axial cervical pain, bilaterally. He had a mildly positive impingement sign for the right shoulder. Anterior apprehension test, anterior/posterior load and shift tests, and O'Brien's test were negative. DIFFERENTIAL DIAGNOSIS Rotator cuff tendinopathy or tear. Upper cervical radiculopathy. Suprascapular neuropathy. Brachial neuritis. Upper cervical plexopathy. TESTS AND RESULTS Radiographs of cervical spine and left shoulder: normal, MRI of cervical spine: mild left C6 foraminal stenosis. MRI of left shoulder: no evidence of rotator cuff pathology, spinoglenoid cysts, or labrum tear. Electrodiagnostic testing: – conduction delay of the left suprascapular nerve, with 50% less amplitude in the motor unit potential, compared to the right, – 2+ spontaneous denervation activity in the left supraspinatus and infraspinatus muscles, with mild evidence of reinnervation. – normal conduction study of other peripheral nerves and normal needle electromyography study in other left upper limb and cervical paraspinal muscles. FINAL DIAGNOSIS Left suprascapular neuropathy with some axonal loss. TREATMENT AND OUTCOMES Utilization of NSAIDs and opiates for pain control. Relative rest from physical activity for the next 4 weeks. Physical therapy for strengthening exercises focusing on the supraspinantus and infraspinatus muscles. Return to sports activities by 4 weeks. Patient became pain free within two months. Repeat electrodiagnostic tests 5 months after onset of pain revealed complete reinnervation of the supraspinatus muscle, but incomplete reinnervation of the infraspinatus muscle, which showed continued spontaneous activity and polyphasic motor units. Recovery of full strength of supraspinatus muscle within 8 months, but only moderate recovery of strength of infraspinatus muscle.