Anterior decompression in the management of unilateral cervical spondylotic amyotrophy

Cervical spondylotic amyotrophy is a rare clinical condition. The purpose of this study was to investigate the effects of anterior decompression in patients with unilateral upper-extremity amyotrophy caused by cervical spondylosis. The authors retrospectively analyzed the records of 31 patients (23 men and 8 women) who underwent anterior decompressive surgery for cervical spondylotic amyotrophy at the authors' institution between 2000 and 2011. Demographic characteristics, pre- and postoperative results of imaging studies, and postoperative muscle power improvement were reviewed at a mean follow-up of 22.2 months (range, 14-36 months). Patients were divided into proximal (n=21) and distal (n=10) types according to the most severely atrophic muscle, and the 2 groups were compared statistically. The most commonly affected intervertebral level in proximal-type patients was C4-C5, whereas that in distal-type patients was C5-C6. Impingements against the ventral nerve root and anterior horn were observed in 22 and 25 cases, respectively, with 16 cases having both impingements. Eighty-one percent of proximal-type patients gained 1 or more grades of muscle power improvement on manual muscle testing, whereas 40% of distal-type patients improved. Within 15 postoperative days, 57% of proximal-type patients attained subjective or objective improvement of muscle power, whereas all distal-type patients failed to improve. Anterior decompression was effective for most patients with unilateral cervical spondylotic amyotrophy, although postoperative muscle power improvement in distal-type patients was inferior to that in proximal-type patients. Furthermore, compared with the proximal type, the distal type showed a slower postoperative recovery.