Relative safety of anterior microsurgical decompression versus laminoplasty for cervical myelopathy with a massive ossified posterior longitudinal ligament

Study Design. A retrospective clinical study was conducted. Objective. To investigate the relative safety of anterior microsurgical decompression with iliac strut graft fusion versus laminoplasty for a massive ossified posterior longitudinal ligament in the cervical spine. Summary of Background Data. The question of how the treatment for cervical myelopathy associated with a massive ossified posterior longitudinal ligament can be improved remains unclear. Methods. Addressing this question involved analyzing the data for 26 patients who had undergone either an anterior (n = 14) or posterior procedure (n = 12) for a large ossified posterior longitudinal ligament with the thickness exceeding 50% of the bony canal diameter (average, 65%; range 52-81%). Results. The two groups showed no statistical difference in preoperative factors including age, duration of symptoms, functional score, maximal occupancy ratio of the ossified posterior longitudinal ligament to the canal, and magnetic resonance findings such as the longitudinal extent of distinct cord indentations and the degrees of spinal cord flattening. Despite comparable postoperative improvement of the cord flattening between the two groups, the anterior procedure showed a significantly better functional result (P < 0.003) with no neurologic complications. In comparison, laminopasty was associated with a significant neurologic deterioration immediately after surgery in four patients (33%). Conclusions. Anterior microsurgical decompression for a massive ossified posterior longitudinal ligament, although technically more demanding, seems counterintuitively safer than laminoplasty. For a better understanding of the underlying mechanism for neurologic worsening after laminoplasty, electrophysiologic monitoring of the spinal cord and the roots function seems essential not only during surgery, but also during presurgical positioning of the patient.