C5 palsy after laminectomy and posterior cervical fixation for ossification of posterior longitudinal ligament

Objective: To investigate the imaging findings correlated with C5 root palsies in the patients undergoing laminectomy and lateral mass screw fixation for ossification of posterior longitudinal ligament (OPLL), and clarify its pathogenic mechanism. Methods: The series included 49 patients with OPLL. Characteristics of preoperative and postoperative x-ray, computed tomography, and magnetic resonance images were compared between the patients with and those without C5 root palsies. Results: Postoperative C5 root palsies occurred in 9 patients 6 to 64 hours postoperatively. They tended to have increased cervical lordosis and severe OPLL. However, there was no significant positive correlation with an increase in T2-weighted hyper-intense foci on magnetic resonance studies. Conclusions: The tethering effect on the root seemed to be the main pathogenic mechanism of C5 root palsies in this study.