Prospective Study and Multivariate Analysis of the Incidence of C5 Palsy After Cervical Laminoplasty

Study Design. A prospective comparative study about the incidence of postoperative C5 palsy and multivariate analysis of the risk factors of C5 palsy. Objective. To clarify the risk factors of occurrence of C5 palsy after laminoplasty (LP) by comparing the 2 surgical procedures of open-door and double-door LP prospectively. Summary of Background Data. The incidence of C5 palsy has been reported to average 4.6%, and there has been no difference of the incidence among surgical procedures. However, there were only indirect retrospective studies. Methods. A total of 146 patients who underwent the LP procedure between 2006 and 2007 were studied prospectively. In 2006, the patients were assigned to undergo the open-door LP, and in 2007, they were assigned to undergo the double-door LP. The incidence of postoperative C5 palsy was compared prospectively between these 2 LP procedures, and the risk factors of C5 palsy were detected with multivariate logistic regression analysis. Results. Postoperative C5 palsy occurred in 7 of 73 cases after open-door LP (9.6%) and in 1 of 73 cases after double-door LP (1.4%). The incidence of C5 palsy after open-door LP was statistically higher than the one after double-door LP (P = 0.029), and open-door LP was recognized as a significant risk factor for postoperative C5 paralysis (odds ratio: 69.6, P = 0.043). In addition, ossification of posterior longitudinal ligament (OPLL) was recognized as a significant risk factor for postoperative C5 paralysis (odds ratio: 43.8, P = 0.048). Conclusion. This study showed significant evidence indicating the higher risk of postoperative C5 palsy in open-door LP than double-door LP. Because OPLL as well as open-door LP were recognized as the risk factors of C5 palsy, asymmetric decompression by open-door LP might introduce imbalanced rotational movement of spinal cord and result in C5 palsy. We recommend double-door LP to minimize the postoperative C5 palsy, in particularly, if the patient has OPLL.