259 - A MRI characterization of the dorsal cervical cord migration behaviour...

General Session: Cervical-1

Presented by: G. Liu Ka Po - View Audio/Video Presentation (Members Only)

Author(s):

G. Liu Ka Po(1), B.H. Lee(2), E. Poh(3), H.K. Wong(1)

(1) National University Hospital, Singapore, Singapore
(2) Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
(3) University of Manchester, Manchester, United Kingdom

Abstract

Introduction: Conventional C3-C7 open door laminoplasty is a well-established technique in the treatment of cervical myelopathy at the expense of high percentage of post-operative axial neck pain and cervical kyphosis. Recent muscle preserving hybrid form of laminoplasty involving a C3 dome osteotomy, open door laminoplasty of C3-C6 and undercutting of the proximal segment of the C7 laminae has been developed to reduce such complications. However there are concerns about inadequate dorsal spinal cord migration in hybrid laminoplasty especially at C3 and C7. The aim of this study is to use Magnetic Resonance Imaging (MRI) to demonstrate and quantify the migration pattern of the spinal cord in the hybrid open-door laminoplasty. Methodology: 20 consecutive patients who underwent hybrid open-door laminoplasty were recruited for this study. 5 additional cases of conventional open-door C3-C7 laminoplasty were used for comparison. All patients had cervical spondylotic myelopathy with cord compression from C3 to C7. Pre-operative and post-operative MRI images were reviewed. Dorsal spinal cord migration pattern and dural sac expansion after laminoplasty were measured using ImageJ software. Statistical analysis of the data collected was carried out by IBM SPSS Statistics Version 21.

Results: 15 Males and 5 Females were recruited for the hybrid laminoplasty (average age of 62.2, 45-73yrs). 5 Males included for conventional laminoplasty group. In the hybrid laminoplasty group, the dorsal spinal cord migration distances was represented by the anterior CSF distance (defined as distance from PLL to anterior dura surface in mid sagittal T2 MRI image) at C3, C4, C5, C6 and C7 and were measured as 1.54, 1.01, 0.70, 1.62 and 2.75 mm respectively. These improved to 1.97, 2.08, 2.61, 3.21 and 3.09 mm at the respective levels post-operatively. For the conventional laminoplasty group, the anterior CSF distances at C3, C4, C5, C6 and C7 were 1.57, 1.14, 0.90, 0.52, and 3.33 respectively. Postoperatively were improved to 2.29, 2.26, 2.74, 4.11 and 5.59 mm respectively. There was a statistical significant increase in postoperative spinal canal diameter, dura sac expansion and dorsal spinal cord migration when compared to preoperative measurements in both groups. A greater increase of postoperative dura sac expansion was noted in hybrid laminoplasty at C3-4 (13.4%), C4-5(17.3%) and in conventional laminoplasty at C5-6 (10.1%), C6-7 (46.8%). A statistical significant increase in dura sac expansion at C6-7 and dorsal cord migration at C6, C7 were noted in conventional laminoplasty group when compared to the hybrid group. No statistical difference found in age, pre, postop sagittal Xray alignments and JOA scores between 2 groups, but a trend towards a more reduction of postoperative lordosis was noted in the conventional laminoplasty.

Conclusion: To the best of the author's knowledge, this is the first study to characterize hybrid open-door laminoplasty demonstrates a comparable MRI dorsal spinal cord migration and dura sac expansion when compared to the conventional open-door laminoplasty in the treatment of C3-7 cervical myelopathy. Increased dorsal cord migration noted at C6, C7 in the conventional laminoplasty suggests increase nerve roots traction and possible increased postoperative C5, C6 palsy development.