Peripheral Nerve Transfers in the Treatment of Cervical Spondolytic Amyotrophy
Douglas C Ross, MD MEd FRCS(C); Roth | McFarlane Hand and Upper Limb Centre, Division of Plastic Surgery, Western University, London, ON, Canada; TA Miller, MD; Rehabilitation Medicine/ Hand and Upper limb Centre, St. Joseph's Health Centre, University of Western Ontario, London, ON, Canada; Charmaine Baxter, MD; Western University, London, ON, Canada; Christopher Doherty, MD, FRCSC; Plastic and Reconstructive Surgery, St. Joseph's Health Care Center, Western University, London, ON, Canada
Purpose: Cervical Spondolytic Amyotrophy (CSA) is an uncommon disorder characterised by progressive, disabling upper extremity atrophy and weakness. Vascular insufficiency involving the anterior horn cell has been implicated. Cervical decompression approaches have produced variable results. The purpose of this paper is to report the use of nerve transfers to restore upper extremity function in CSA.
Methods: Eight patients with CSA were treated and reviewed. Pre-operative imaging and neurosurgical evaluation were completed in all. Comprehensive electrodiagnostic assessment to assess for peripheral nerve deficits as well as the status of potential donor nerves was undertaken. MRC strength testing pre- and post-operatively was completed. Patient-rated outcomes were assessed using a DASH questionnaire. Electromyographic findings at 5 and 12 months post-operatively were recorded.
Results: Seven patients demonstrated clinical, electrodiagnostic and imaging evidence of CSA at the C5/6 (proximal type) levels while one was of the "distal" type (C8/T1). All had been assessed in neurosurgical consultation and judged not to be candidates for decompressive surgery based upon criteria associated with poor outcomes (MRC grade <2, duration of symptoms, low CMAP amplitudes). All demonstrated marked wasting in the affected myotomes. Pre-operative electromyography demonstrated either single or no motor units in affected myotomes. Average age was 64.9 years with the majority being male (7 of 8). Mean duration of severe weakness pre-operatively was 13.2 months. The majority of patients were treated with "triple nerve transfers" to restore function of the suprascapular, axillary and musculocutaneous nerves. Average followup was 22.2 months (8-68). One patient died from metastatic bowel cancer 15 months post-operatively. Of patients with adequate post-operative followup, the average increase in elbow flexion was MRC 3+ (with restoration of absent supination), and the average increase in shoulder abduction was MRC 2+. EMG evidence of reinnervation was first observed at 5 months post-operatively and was used to trigger a course of rehabilitation emphasizing neuromuscular stimulation, biofeedback and neuroplasticity. Patient-rated DASH scores showed significant improvement.
Conclusions: CSA is an uncommon but highly disabling disorder. Nerve transfers should be considered for patients who are poor candidates for decompressive neurosurgical procedures. Outcomes of nerve transfer surgery are encouraging despite advanced age and prolonged pre-operative weakness.
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