Surgical outcome of posterior decompression for cervical spondylosis with unilateral upper extremity amyotrophy

Study Design. Case studies of patients with cervical spondylosis with unilateral upper extremity amyotrophy. Objective. To clarify the surgical outcome of posterior decompression for this amyotrophy. Summary of Background Data. Cervical spondylosis sometimes causes a characteristic severe muscular atrophy without sensory disturbance or lower-extremity dysfunction, which is the so-called "cervical spondylotic amyotrophy." However, response to treatment, especially to posterior decompression, has not been well understood. Method. This study included 32 patients. All underwent posterior cervical laminoplasty, and 22 patients had an additional foraminotomy. Preoperative and postoperative muscle power and results of imaging and electrophysiologic studies were evaluated. The follow-up period averaged 78 months. Whether impingement was against the ventral nerve root (VNR) or anterior horn (AH) in the spinal cord was assessed according to these findings. These cases were divided into proximal type and distal type according to the most severely atrophic muscle and compared statistically. Results. Severe preoperative muscle atrophy was observed in the deltoid and biceps muscles of 24 patients (proximal type) and in the forearm and hand muscles of 8 patients (distal type). Impingements against the VNR and AH were observed in 21 and 28 cases, respectively, and 17 cases had impingement of both the VNR and AH. Improvements in muscle atrophy after surgery were observed in 25 cases. In proximal-type patients, muscle power improved in 92% of cases but was improved in only 38% of the distal-type cases. Conclusions. Laminoplasty and foraminotomy were effective in the treatment of most patients with this syndrome, although the outcome in the distal type was inferior to that in the proximal type.