Neurological Complications of Cervical Laminoplasty for Patients With Ossification of the Posterior Longitudinal Ligament-A multi-Institutional Retrospective Study

Study Design. Retrospective multi-institutional study. Objective. To investigate the incidence of neurological deficits after cervical laminoplasty for ossification of the posterior longitudinal ligament (OPLL). Summary of Background Data. According to analysis of long-term results, laminoplasty for cervical OPLL has been reported as a safe and effective alternative procedure with few complications. However, perioperative neurological complication rates of laminoplasty for cervical OPLL have not been well described. Methods. Subjects comprised 581 patients (458 men and 123 women; mean age: 62 + 10 years; range: 30-86 years) who had undergone laminoplasty for cervical OPLL at 27 institutions between 2005 and 2008. Continuous-type OPLL was seen in 114, segmental-type in 146, mixed-type in 265, local-type in 24, and not judged in 32 patients. Postoperative neurological complications within 2 weeks after laminoplasty were analyzed in detail. Cobb angle between C2 and C7 (C2/C7 angle), maximal thickness, and occupying rate of OPLL were investigated. Pre- and postoperative magnetic resonance imaging was performed on patients with postoperative neurological complications. Results. Open-door laminoplasty was conducted in 237, double-door laminoplasty in 311, and other types of laminoplasty in 33 patients. Deterioration of lower-extremity function occurred after laminoplasty in 18 patients (3.1%). Causes of deterioration were epidural hematoma in 3, spinal cord herniation through injured dura mater in 1, incomplete laminoplasty due to vertebral artery injury while making a trough in 1, and unidentified in 13 patients. Prevalence of unsatisfactory recovery not reaching preoperative level by 6-month follow-up was 7/581 (1.2%). Mean occupying rate of OPLL for patients with deteriorated lower-extremity function was 51.2 +/- 13.6% (range, 21.0%-73.3%), significantly higher than the 42.3 +/- 13.0% for patients without deterioration. OPLL thickness was also higher in patients with deterioration (mean, 6.6 +/- 2.2 mm) than in those without deterioration (mean, 5.7 +/- 2.0 mm). No significant difference in C2/C7 lordotic angle was seen between groups. Conclusion. Although most neurological deterioration can be expected to recover to some extent, the frequency of short-term neurological complications was higher than the authors expected.