The Clinical And Experimental Study On The Relationship Between The Pathogenesis Of Cervical Radiculopathy And Related Pathway In Cervical Spinal Cord

Objective: Explore the relationship between the pathogenesis of cervical radiculopathy and certain pathway in cervical spinal cord. Describe the pathway and projections of nerve fibers which finally construct the nerve root. Discuss the existence and location of short propriospinal tracts that connect and regulate the segments of cervical spinal cord.Methods: (1) Clinical study: 62 cases of cervical radiculopathy were selected into a retrospective study on the relationship between the clinical manifestation and imageology (including X-ray & MRI). (2) Selective retrograde tract tracing on C7 nerve root of rat: 36 adult SD rats were selected and divided randomly into 3 groups (Group A: executed 6 hrs after tracer injection; Group B: executed 12 hrs after tracer injection; Group C: executed 12 hrs after tracer injection.), 12 rats for each group. For each animal, nerve roots which joined the right brachial plexus were abscised except C7 nerve root. As the tracer, 4% WGA-HRP were injected into the brachial plexus on the right side. After 6, 12, and 24hrs since the tracer were introduced, animals were executed, and the cervical spinal cords were obtained to prepare frozen sections. And then, samples were reacted with DAB before microscopic observation. The researchers recorded the location and counts of positive nerve fibers and neurons. All data were processed with statistical treatment. (3) The study on c-fos and c-jun expression in rat cervical spinal cord that answered to the injury of right C7 nerve root: 84 adult SD rats were selected and divided randomly into several groups: abscise group for Fos(Group F), abscise group for Jun(Group J), sham operated group for Fos(Group WF), sham operated group for Jun(Group WJ), control group for Fos(Group NF), control group for Jun (Group NJ). Within abscise group and sham operated group, different time period since injury were concerned, so that subgroup of 2hrs, 4hrs, and 6hrs were additionally discriminated. For each animal in the abscise group, the right C7 nerve root was abscised. On certain time points after operation,animals were executed, and the cervical spinal cords were obtained to prepare frozen sections. And then, samples were stained with the method ABC immuno histochemistry. The researchers recorded the location and counts of positive neurons. All data were processed with statistical treatment.Results: (1) What we found in the clinical study is: 88.7% cases presented the manifestation of multiple nerve roots impairments. The MRI showed lateral stenosis of the spinal canal in 61.3% cases and central-lateral stenosis in 21% cases. Only 17.7% cases presented direct compression of the nerve roots in the intervertebral foramen. (2) Selective retrograde tract tracing on C7 nerve root of rat:①6hrs after the tracer injected, in the samples of C7 spinal cord, positive nerve fibers could be observed in the white matter, started from the dorsal lateral and ventral lateral grooves of spinal cord, and ended in theⅨlayer of anterior horn andⅠ,Ⅱlaminae of the posterior horn. Similar location of positive fibers also could be seen in C5 and C6 segment, but the ratios of positive area of latter laminae were much less than that in C7.②In 12 hrs group, positive neurons were found in gray matter of C7, C6, and C5, located inⅨlayer of ventral horn andⅠ,Ⅱlaminae of the dorsal horn. Counts of positive neurons showed largest number in C7, and smallest in C5.③In 24 hrs group, positive fibers were observed from C7-C5 segment. Compared with the situation of 6 hrs group, the distribution of fibers is wider. Location of positive neurons of this group is different from that of 12 hrs group. More stained neurons gathered inⅢ,Ⅳ,Ⅴ,Ⅵ,Ⅶ,Ⅷlaminae of gray matter. (3) The study on c-fos and c-jun expression in rat cervical spinal cord that answered to the injury of right C7 nerve root:①The counts and location of C-Fos and C-Jun positive neurons are quite similar in all groups and all segment of spinal cords.②Much more positive neurons could be found in the abscise groups compared with the sham operated groups and control groups, the differences were significant during statistical treatment.③There were significant differences in the count of positive neurons and distribution between time points: Positive neurons were mainly found inⅠ,Ⅱ,laminae andⅨlaminae of C5-7 gray matters 2 hrs after nerve root injury. So long as 6 hrs after injury, more positive neurons were found inⅣ,Ⅴ,Ⅵ,Ⅶ,Ⅷlaminae, no significant differences could be observed between segments.Conclusion:①Stenosis of the intervertebral foramen should not be the only reason for cervical radiculopathy. The clinical manifestation may partially from the compression of the spinal cord in the lateral portion.②with the method of selective retrograde tract tracing, the pathway, grouping, and projection of fibers which construct the nerve root could be described.③Besides C7 doral horn, the afferent fibers of C7 nerve root also project to the dorsal horn of proximal segments; Along with the motor fibers of C7, some efferent fibers from C5 and C6 ventral horns join the construction of C7 nerve root.④Propriospinal tracts that connect the consecutive segments of the cervical spinal cord exist in the white matter, the location is near the gray matter. Neurons responsible to the propriospinal tracts locate inⅣ,Ⅴ,Ⅵ,Ⅶ,Ⅷlaminae of gray matter.⑤The expression of immediate early genes that answer to the nerve root injury can be used in the evaluation of morphology and function for certain pathway in spinal cord.⑥The expressions of c-fos and c-jun gene at 2 hrs after selective C7nerve root injury describe the projection of nerve fibers which construct C7 nerve root.⑦The expressions of c-fos and c-jun gene at 6 hrs after selective C7nerve root injury describe the location of neurons responsible to the propriospinal tracts. Those neurons located in theⅣ,Ⅴ,Ⅵ,Ⅶ,Ⅷlaminae of gray matter.