Predictors of Motor Weakness and Delayed Recovery in Cervical Disk Herniation.

STUDY DESIGN: Retrospective study.

OBJECTIVE: To identify the significant risk factors for motor weakness caused by cervical disk herniation and for delayed recovery after surgery.

SUMMARY OF BACKGROUND DATA: There were a few clinical trials for detecting the significant risk factors for motor weakness after anterior cervical surgery.

MATERIALS AND METHODS: We retrospectively examined 72 patients with degenerative disk disease of the cervical spine who were treated with single-level anterior cervical discectomy and fusion. The possible risk factors, including age, sex, symptom duration, operation time, surgery level, preoperative radiologic parameters, and preoperative Neck Disability Index score, were evaluated using multivariate logistic regression analysis.

RESULTS: The patients included 22 women and 50 men; average age, 47.1±7.8 years. Of these 72 patients, 38 (52.8%) patients had motor deficit before surgery. Complete recovery of motor deficit was seen in 33 (86.8%) patients, and the average duration from surgery to complete recovery was 4.2 months. Multivariate logistic regression analysis showed that disk height (P=0.001, odds ratio=0.32), percentage of herniated nucleus pulposus (HNP) in the spinal canal (P=0.0012, odds ratio=1.24), and presence of signal intensity change in the spinal cord (P=0.0015, odds ratio=35.57) were important risk factors for motor weakness. When the cut-off value of disk height was 5.8 mm, the sensitivity and specificity were 39.5% and 94.1%, respectively. When the cut-off value of HNP in the spinal canal was 28.1%, the sensitivity and specificity were 57.9% and 82.4%, respectively. Furthermore, signal intensity change was identified as an important risk factor for delayed recovery.

CONCLUSIONS: Decreased disk height, percentage of HNP in the spinal canal, or presence of signal intensity change in the spinal cord seem to be the important risk factors for motor weakness in patients with cervical disk herniation. Moreover, the presence of signal intensity change in the spinal cord seems to be an important risk factor for delayed recovery.