Anatomical study on C5 nerve palsy after posterior cervical single-door laminoplasty

English Keywords:Expansive open-door laminoplasty  C5 plasy  Anatomical mechanism  The meningovertebral ligaments  Nerve root lesion

English Abstract:

  【Abstract】 Objectives: To investigate the possible anatomical mechanism of C5 nerve palsy after cervical expansive single-door laminoplasty. Methods: Eight whole cervical embalmed cadavers (54 to 78 years, averaged 66.4±7.3 years) were studied. After dissecting postvertebral muscles, the bilateral laminae were exposed. A gutter was created above the inner cortex at the medial border of the facet joints as hinges, while another gutter on the contralateral side penetrated the inner cortex and the spinal canal as open side. After lifting the open side of the laminae, any tough ligamentous structures between the posterior dura sac and the ligamentumflavum or laminae were observed and identified after removing the adipose tissue. The quantity, morphology, origin, insertion and the spatial orientation of the meningovertebral ligaments at the C3-7 region were observed. The length, width, and thickness of the ligamentous structures were measured with a millimeter caliper(accurate to 0.01mm). Then, changes of the dura sac and roots were observed at different segments. In addition, the most cranial and caudal lengths of the C4-C8 ventral rootlets were measured. Results: A total of 37 meningovertebral ligaments were found in 8 cervical spine specimens, connecting the posterior wall of the dura sac to ligamentum flavum or laminae. Ligament length varied from 7.37-20.09mm(12.24±3.21mm); the thickest one is 1.12mm. The meningovertebral ligaments had a tendency to be abundant at C3-C4 of spinal cord. Besides, the most cranial and caudal lengths of C5 ventral rootlets (13.18±1.12mm, 8.07±1.11mm) were the shortest in the vulnerable segments when lifting up the open side of lamina, the meningovertebral ligaments became tight, and the shape of the dura sac was changed, therefore the displacement of spinal cord and nerve root was observed. Conclusions: The meningovertebral ligaments might play an important role in the occurrence of postoperative C5 nerve palsy. Release of the meningovertebral ligaments may be effective in reducing the incidence of postoperative C5 nerve palsy.