Spine Journal - 2026-05-01 - Journal Article
Limited cervical laminectomy prevents postoperative delayed motor palsy: an experimental study using a rat model.
Yokota A, Neo M, Fujishiro T, Hayama S, Adachi F, Otsuki S
Topics
Key Takeaway
Wide laminectomy produced significantly greater posterior spinal cord displacement and longer deltoid MEP latency than limited laminectomy at postoperative days 10 and 14 in a rat model, supporting root tethering as the primary mechanism of C5 palsy.
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Summary
This in vivo rat study investigated whether laminectomy width drives C5 palsy (C5P) by quantifying posterior spinal cord shift and anterior rootlet elongation via CT-myelogram and motor evoked potentials across limited laminectomy, wide laminectomy, and sham groups. Wide laminectomy produced significantly greater cord displacement at C4–C6 and greater C5–C7 anterior rootlet elongation than limited laminectomy at days 10 and 14. Deltoid MEP latency was significantly prolonged in the wide laminectomy group versus limited laminectomy at days 10 and 14, and versus sham at all time points, while triceps MEP latency showed no significant differences across groups.
Key Limitation
The rat model lacks pre-existing spondylotic cord compression and tethering from osteophytes or ligamentous hypertrophy, which are the clinical conditions in which C5P actually occurs, making mechanistic extrapolation to human DCM surgery uncertain.
Original Abstract
BACKGROUND CONTEXT
Whether the width of laminectomy is a risk factor for the development of C5 palsy (C5P) remains controversial, partly due to confounding variables inherent in retrospective clinical studies.
PURPOSE
To investigate the relationship between laminectomy width, posterior shift of the spinal cord, and elongation of the anterior rootlets using an animal model.
STUDY DESIGN
Basic in vivo experimental study.
METHODS
A total of 18 Sprague-Dawley rats were randomly assigned to 3 groups: Group L (limited laminectomy, N = 6), Group W (wide laminectomy, N = 6), and Group S (sham surgery, N = 6). Animals were evaluated pre- and postoperative days 3, 10, and 14. The widths of the laminectomy, posterior spinal cord shift, and anterior rootlet length were quantified using computed tomography-myelogram images. Motor evoked potentials (MEPs) were recorded from the deltoid (C5-C6 innervated) and triceps brachii (C7-T1 innervated) muscles.
RESULTS
Postoperative posterior shift of the cervical cord was observed in both experimental groups. However, Group W showed significantly greater displacement than Group L at the C4-C6 vertebral levels on postoperative days 10 and 14, corresponding to a greater elongation of the C5-C7 anterior rootlets. MEP latency of the deltoid muscle was significantly longer in Group W than in Group L at postoperative days 10 and 14, and significantly longer than in Group S at all postoperative time points. Conversely, no statistically significant differences in MEP latency of the triceps brachii were observed among all groups.
CONCLUSIONS
Limited laminectomy may prevent C5P by minimizing elongation of the intradural anterior rootlets caused by gradual posterior shift of the cervical spinal cord.
CLINICAL SIGNIFICANCE
This study provides insights for clinicians regarding C5 palsy prevention. By limiting the width of degree of laminectomy, posterior shift of the spinal cord, and thus elongation of the anterior rootlets, can be reduced. These findings support the hypothesis that root tethering from spinal cord shift is a likely mechanism of C5P.