Postoperative Paralysis from Thoracic Ossification of Posterior Longitudinal Ligament (OPLL) Surgery-Risk factor of Neurologic Injury: Nationwide Multi-Institution Survey

STUDY DESIGN.Retrospective case control study. OBJECTIVE.The purpose of this study was to examine the factors of postoperative paralysis in patients who have undergone thoracic OPLL surgery. SUMMARY OF BACKGROUND DATA.A higher percentage of thoracic OPLL cases experience postoperative aggravation of paralysis than cervical OPLL cases, including cases that presented great difficulties in treatment. However there was few report to prevent paralysis thoracic OPLL. METHODS.The 156 cases who had received thoracic OPLL surgery were selected as the subjects of this study. The items for review werethe duration of disease; the preoperative muscle strength (Muscle Manual TestingMMT); OPLL levels (T1/2-4/5high, T5/6-8/9middle, T9/10-11/12low); the spinal canal occupancy ratio; the ratio of yellow ligament ossification as a complication; the ratio of Tc-MEP derivation; the preoperative/postoperative kyphotic angles in the thoracic vertebrae; the correction angle of kyphosis; the duration of surgery; and the amount of bleeding. The subjects were divided into two groups based on the absence or presence of postoperative paralysis to determine the factors of postoperative paralysis. RESULTS.Twenty-three cases (14.7%) exhibited postoperative paralysis. Multivariate analysis identified factors associated with postoperative paralysisthe duration of disease (OR = 3.3); the correction angle of kyphosis (OR = 2.4); and the ratio of Tc-MEP derivation (OR = 2.2). CONCLUSIONS.The risk factors of postoperative paralysis are a short duration of disease and a small correction angle of kyphosis. Additionally, ratios of Tc-MEP derivation below 50% may anticipate paralysis.Level of Evidence4