Simple presurgical method of predicting C5 palsy after cervical laminoplasty using C5 nerve root ultrasonography.

Objective: The incidence of C5 palsy after cervical laminoplasty is approximately 5%. Because C5 palsy is related to cervical foraminal stenosis at the C4-5 level, the authors hypothesized that cervical foraminal stenosis can be diagnosed by examining the C5 nerve root (NR) using ultrasonography. The purpose of this study was to investigate whether postoperative C5 palsy could be predicted using ultrasonography.

Methods: This study used a prospective diagnosis design. In total, 140 patients undergoing cervical laminoplasty were examined with ultrasound. The cross-sectional area (CSA) of the C5 NR was measured on both sides before surgery, and the incidence of postoperative C5 palsy was examined. The difference between the CSA of the patients with and without C5 palsy and the lateral differences in the C5 palsy group were determined.

Results: The incidence of C5 palsy was 5% (7 cases). Symptoms manifested at a median of 5 days after surgery (range 1-29 days). The CSA of the C5 NR on the affected side was significantly enlarged in the C5 palsy group compared with that in the no-C5 palsy group (p = 0.001). In addition, in the patients who had C5 palsy, the CSA of the C5 NR was significantly enlarged on the affected side compared with that on the unaffected side (p = 0.02). Receiver operating characteristic analysis indicated that the best threshold value for the CSA of the C5 NR was 10.4 mm, which provided 91% sensitivity and 71% specificity.

Conclusions: C5 palsy may be predicted preoperatively using ultrasound. The authors recommend the ultrasonographic measurement of the CSA of the C5 NR prior to cervical laminoplasty.