General Session: Cervical Motion Preservation
Presented by: J.H. Ng - View Audio/Video Presentation (Members Only)
J.H. Ng(1), G. Liu(2), J.Y.W. Tan(1), H.K. Wong(2)
(1) National University of Singapore, Singapore, Singapore
(2) National University Health System, Singapore, Singapore
Introduction: Posterior cervical approach has become the treatment of choice for cervical spinal cord compression related pathology in more than three vertebral levels. Previous studies compared clinical outcomes of cervical laminoplasty with laminectomy and have reported inconsistent findings. There has been a recent development of a hybrid laminoplasty approach (C3 dome osteotomy, C4-6 laminoplasty and upper C7 laminectomy) with muscle sparing techniques. To the best of the authors' knowledge, there are no studies comparing the results of hybrid laminoplasty with laminectomy with fusion. The aim of this study is to compare and evaluate the surgical outcomes of hybrid laminoplasty with laminectomy with fusion in terms of radiological findings.
Methods: A retrospective review of 42 consecutive patients, who had undergone cervical laminectomy with fusion (LF) or hybrid laminoplasty (HLP) by a single surgeon, was performed. Surgical outcomes were assessed and Image J software was used to evaluate pre- and post-operative Magnetic Resonance Imaging (MRI) scans for posterior cord migration and dural sac expansion of the two groups (LF and HLP). Radiological data captured was analysed using SPSS software.
Results: 36 cases with pre- and post-op MRI were included in the study. Average follow up duration was 1.5 years. 16 patients had laminectomy with fusion (LF) and 20 had hybrid laminoplasty (HLP). There were no statistically significant differences between the LF and HLP group in terms of age, gender, follow-up duration, pre-operative diagnosis and pre-operative JOA score. There were however 2 cases of post-operative C5 palsy in LF compared to none in HLP. A trend is shown with the laminectomy with fusion (LF) group displaying greater dorsal cord migration than the hybrid laminoplasty (HLP) group at all levels from C2-T1. Comparing between cervical spinal levels, the extent of dorsal cord migration is shown to be greatest at the level of C4-5 in LF (1.94±1.60 mm, p=0.01) and C5-6 in HLP (1.71±1.17 mm, p=0.00). In comparing patients with post-operative C5 palsy with those who did not acquire C5 palsy, dorsal migration was found to be significantly greater in the C5 palsy group at the levels of C4-5 (4.38±0.50 mm vs 1.64±1.04 mm, p=0.02), C5-6 (4.97±0.99 mm vs 1.57±1.29 mm, p=0.02) , C6-7 (4.20±0.83 mm vs 0.77±1.09 mm, p=0.02) and C7-T1 (1.74±0.96 mm vs 0.01±1.33mm, p=0.045) as compared to the non-C5 palsy group.
Conclusion: This is the first MRI study to prove that there is a trend towards greater posterior cord migration in laminectomy with fusion compared to hybrid laminoplasty in patients presenting with cervical myelopathy. A statistically significant greater dorsal cord migration was found at C4-5 spinal level in patients with C5 palsy.