Sympathetic nerve innervation in cervical posterior longitudinal ligament as a potential causative factor in cervical spondylosis with sympathetic symptoms and preliminary evidence.

Unlabelled: Sympathetic symptoms associated with cervical disorders, such as vertigo, headache, dizziness, etc., are common clinical disorders bewildering both clinicians and patients. In our clinical practice we observed that sympathetic symptoms associated with cervical disorders were apparently relieved in some patients after undergoing routine anterior cervical decompression and fusion plus posterior longitudinal ligament (PLL) resection. This study was designed to investigate the sympathetic nerve innervations in the cervical PLL and its potential correlation with cervical sympathetic symptoms such as vertigo.

Method: In animal research, cervical PLLs of 9 adult rabbits were harvested and stained with sucrose-phosphate-glyoxylic acid (SPG), which is a specific fluorescence staining method for sympathetic postganglionic fibers. In human research, cervical PLL of 8 patients of cervical spondylosis with sympathetic symptoms were harvested during surgery and stained with SPG. All sections were observed under fluorescence microscope. Sympathetic symptoms were evaluated using the sympathetic symptom 20-point score preoperatively and at 1 week, 2-month, and 6-month postoperatively.

Results: In rabbit specimens, a large number of sympathetic postganglionic fibers were distributed in the cervical PLL of every segment. The density of sympathetic fibers distributed in the intervertebral portion of PLL was more than that in the vertebral portion. Compared with deep layer section, the nerve fibers in the superficial PLL layer section were thicker and more densely populated. Existence of sympathetic postganglionic fibers was also confirmed in human specimens. Those nerve fibers were mostly short and isolated in areatus form, with non-interwoven branches. The mean sympathetic symptoms score decreased significantly from 6.6 ± 2.6 before surgery to 2.0 ± 1.9 at 6 months postoperatively after anterior cervical decompression and fusion with PLL removed.

Conclusion: According to the experimental result and clinical practice, we hypothesized that sympathetic nerve fibers distributed in PLL may represent a pathologic basis of stimulation induced by cervical vertebral degenerative changes and thus are susceptible to being a potential causative factor in cervical spondylosis with sympathetic symptoms.