Enlarged laminectomy for ossification of posterior longitudinal ligament in cervical spine

Abstract

Objective To introduce the surgical strategy of enlarged laminectomy （with partial facet joint dissection to expose the nerve root）, and to discuss its benefit for cervical ossification of the posterior longitudinal ligament（OPLL） with myelopathy. Methods Totally 82 patients with cervical OPLL were treated by enlarged laminectomy from January 1998 to December 2005. There were 47 males and 35 females, with an average age of 57 years （ranged, 39-84 years）. Among them, there were 31 cases of the solitary type, 40 cases of the continuous type, and 11 cases of the mixed type. JOA scoring system and the visual analogue scale （VAS） scoring were applied to evaluate the neurological function and neck/shoulder pain respectively.Ishihara method was employed to measure cervical curvature index（CCI）. The degree of spinal cord backward expanding and displacement were calculated in MR1. Results The mean decompression length was 5.2 （4-6） segments. The mean follow-up duration was 41 months （ranged, 13-58 months）. JOA score has improved from 10.9（7-15） preoperatively to 13.9（11-17） postoperatively （t=14.65, P〈0.01）. The excellent and good rate was 98.7%. The palsy of C5 nerve root occurred in only 2 patients, both recovered after surgery. Zhe mean postoperative VAS score was 1.4（1-3）, comparing with the preoperative score of 5.3 （4-6）. The pain in neck/shoulder was alleviated obviously （t=15.46, P〈0.01 ）. CCI decreased from 18.8% to 10.5%（t=5.03, P〈0.01 ）,but did not follow by neuron function deterioration. MRI indicated that the cross-sectional area at the level of maximum compression of the dural sac increased from 85.4 mm2 preoperatively to 153.8 mm2 postoperatively （t=16.33, P〈0.01）, and the mean spinal cord posterior shift was 6.2 mm （t=15.35, P〈0.01）. Conclusion The enlarged laminectomy is proved to be effective in treating cervical OPLL, in terms of significant posterior shift of the spinal cord, relief of cervical/shoulder pain, lower rate of the palsy of C5 nerve root, with no recurrence of spinal cord compression symptom. Key words: Ossification of posterior longitudinal ligament; Laminectomy; Cervical vertebrae; Decompression, surgical