Reconstruction of shoulder and elbow function using multiple muscle transfers for cervical spondylotic amyotrophy

Cervical spondylotic amyotrophy: a systematic review

PURPOSE

Cervical spondylotic amyotrophy (CSA) is characterized by upper limb muscle weakness and atrophy, without sensory deficits. The pathophysiology of CSA has been attributed to selective injury to the ventral nerve root and/or anterior horn of the spinal cord. This review aimed to delineate the history of CSA and to describe the epidemiology, etiology, pathophysiology, classification, clinical features, radiological and electrophysiological assessment, diagnosis, differential diagnosis, natural history and treatment of CSA.

METHODS

A comprehensive search of PubMed, EMBASE, Cochrane library and Web of Science databases was conducted, from their inception to April 3, 2018.

RESULTS

Clinically, CSA is classified into three types: a proximal-type (involving the scapular muscles, deltoid and biceps), a distal-type (involving the triceps and muscles of the forearm and hand) and a diffuse-type (involving features of both the distal- and proximal-type). Diagnosis requires documentation of muscle atrophy, without significant sensory deficits, supported by careful neurological, radiological and neurophysiological assessments, with amyotrophic lateral sclerosis, Parsonage-Turner syndrome, rotator cuff tear and Hirayama disease being the principle differential diagnoses. Conservative management of CSA includes cervical traction, neck immobilization and physical therapy, with vitamin B12 or E administration being useful in some patients. Surgical treatment, including anterior decompression and fusion or laminoplasty, with or without foraminotomy, is indicated after conservative treatment failure. Factors associated with a poor outcome include the distal-type CSA, long symptom duration, older age and greater preoperative muscle weakness.

CONCLUSION

Although the disease process of CSA is self-limited, treatment remains challenging, leaving scope for future studies. These slides can be retrieved under Electronic Supplementary Material.

Treatment of Cervical Spondylotic Amyotrophy With Nerve Transfers

Cervical spondylotic amyotrophy is characterized by severe, proximal upper extremity weakness including an inability to abduct the shoulder and flex the elbow. Treatment using both medical and surgical decompression approaches has produced variable results. This paper reports the use of nerve transfers (spinal accessory to suprascapular, flexor carpi ulnaris fascicle of ulnar to biceps motor branch, radial nerve branch to triceps to axillary) to restore shoulder and elbow function in a case of unilateral cervical spondylotic amyotrophy involving C5 and C6 myotomes. Evidence of regeneration was observed on electromyography as well as clinically at 5 months postoperatively. At 3 years after surgery, recovery of elbow flexion and shoulder abduction was Medical Research Council grade 4/5 with improved external rotation and considerably improved patient-rated Disabilities of the Arm, Shoulder and Hand scores. We propose that nerve transfers be considered along with other reconstruction modalities in the treatment of cervical spondylotic amyotrophy.