Delayed C5 Palsy After Anterior Cervical Decompression Surgery: Preoperative Foraminal Stenosis and Postoperative Spinal Cord Shift Increase the Risk of Palsy.

OBJECTIVE: Postoperative C5 palsy is a well-known complication after cervical decompression with either a posterior or an anterior approach. Its cause has been discussed more regarding the posterior approach. The main hypothesis is that postoperative spinal cord shift causes root traction and palsy. However, the pathogenesis in anterior cases has not been fully described. Therefore, the purpose of this study was to clarify the risk factors for C5 palsy in the anterior approach through our C5 palsy cases.

METHODS: A total of 149 surgical patients with an anterior cervical lesion were treated by a specific spinal surgeon under consistent same treatment strategy. Of these patients, 88 who satisfied the evaluation criteria were enrolled. Postoperative C5 palsy was defined as postoperative weakness of the deltoid with or without weakness of the biceps brachii. Risk factors of C5 palsy were extracted from clinical backgrounds, surgical approaches, and radiologic findings from patients with palsy.

RESULTS: Four sides of 3 individuals (4.6%) who underwent multiple corpectomy developed C5 palsy. All paralyses became evident several days after the surgery and recovered. Older age, multiple corpectomy, postoperative spinal cord shift, and foraminal stenosis of C4-5 and C5-6 were statistically extracted as causative factor of C5 palsy. In the patients with palsy, distortion of the anterior nerve root as a result of a residual vertebral spur was observed with anterior spinal cord shift after anterior corpectomy.

CONCLUSIONS: Multiple corpectomy for patients with longer anterior lesions and locally developed kyphosis is related to a larger postoperative cord shift, which can cause the occurrence of C5 palsy. Moreover, C4-5 or C5-6 foraminal stenosis can accelerate tethering of the C5 or C6 nerve root. Older patients undergoing multiple corpectomy are susceptible to these risks of palsy. Appropriate patient selection and sufficient additional foraminotomy should be considered for extensive anterior lesions and locally developed kyphosis to avoid postoperative C5 palsy.