Physician Advanced Interventional Pain & sports Medicine Center Owings Mills, Maryland, United States
Case Diagnosis: Shoulder pain after motor vehicle collision
Case Description: IRB exemption was obtained. A 55-year-old female presented with complaints of right shoulder pain 7 months after motor vehicle collision. She had undergone conservative treatment including medication, physical therapy and shoulder injection. Right shoulder pain decreased by 40% after second shoulder injection under ultrasound guidance. MRI of right shoulder showed rotator cuff severe tendinosis; intermediate grade rim rent articular surface partial tear anterior footprint supraspinatus tendon humeral insertion; small subacromial subdeltoid bursal effusion; mild strain or denervation change teres minor muscle belly. There was no evidence of a mass within the quadrilateral space. Nerve conduction studies revealed very mild right carpal tunnel syndrome. EMG of right upper limb revealed denervation potentials in right teres minor muscle and reduced recruitment in right teres minor and right deltoid muscle. Ultrasound was used for needle insertion in periscapular muscles. Patient was referred for surgical consultation.
Discussion: Isolated teres minor denervation has been reported in 3% of patients on routine MRI of shoulder. It may be be associated with other injuries of the rotator cuff or glenohumeral joint. In this study the MRI showed probably denervation of teres minor which was confirmed by EMG. Incidentally the MRI showed denervation in the teres minor partially. In addition the EMG showed decreased recruitment in the right deltoid muscle. EMG findings indicate injury to the axillary nerve. These findings may be important in further treatment of the patient with regards to shoulder stabilization during rehabilitation and after surgery.
Conclusions: This case study shows that axillary nerve injury may present with variable pattern including denervation of partial teres minor (MRI and EMG) and affecting the deltoid muscle (EMG). This may be taken into consideration as it is an important component for rehabilitation and during the decision making process for any shoulder surgery.