[Spinal pathologic changes and axonal regeneration after brachial plexus root anastomosis in rats].
OBJECTIVE
To evaluate the feasibility of direct anastomosis in the rat model of the brachial plexus extravertebral foramen nerve root division of C5-7. Methods Forty-eight SD rats (male or female) aging 4-6 months and weighing 250-300 g were selected to make the model of extravertebral foramen nerve root division of C5-7. The left C5-7 nerve roots, as the experimental sides, were separated to the brachial plexus nerve trunk and the transected roots were sutured to the proximal stump immediately after cutting off the brachial plexus extravertebral foramen nerve root division. The right C5-7 nerve roots, as the control sides, received no operation. The general condition of rats after operation was observed. The gross observation, the histological observation and BDA nerve tracing technology were adopted to observe the wet weight of musculus biceps brachii, the cross section of biceps brachii and the spinal cord and distal nerve trunk at 3 weeks, 3 months and 6 months after operation. Results All rats survived well after operation. Claudication and unfold claw reflex were observed in the experimental sides, and the unfold claw reflex disappeared 3 months later. Comparatively, the control sides were normal. Nerve adhesion aggravated gradually and the neural stems were shriveled within 6 months after operation in the experimental sides. Comparatively, the control sides were normal. The wet weight of biceps brachii in the experimental sides and the control sides at 3 weeks, 3 months and 6 months after operation was (0.28 +/- 0.12), (1.37 +/- 0.33), (0.58 +/- 0.10), (1.36 +/- 0.35), (1.39 +/- 0.31), (1.37 +/- 0.38) g, respectively, indicating significant differences between two sides at 3 weeks and 3 months (P < 0.05), but no significant difference at 6 months (P > 0.05). The modified Marsland and the LFB staining of spinal cord and superior trunk of brachial plexus showed that the number of neurons, cell nuclear and Nissl body decreased and cell bodies changed from swelling to shrinkage, dyeing nerve fibers increased, neural axone was thin and myelin sheath was slightly stained at each time point in experimental side. The number of motor neurons in cornu anterius medullae spinalis in the experimental side was 84.5% +/- 3.2%, 74.4% +/- 4.5%, 73.7% +/- 3.8% of that in the control side at each time point, respectively. HE staining of biceps brachii detected that the muscle denaturation was very serious at 3 months after operation and then recovered. Neural tracing used BDA showed that the closer to the proximal of nerve trunk, the more obviously stained it was of myelin sheath and the more massive of axon at 6 months after operation. And there was almost no myelin and axon stained in musculocutaneous nerve.


CONCLUSIONS
In the rat model of brachial plexus extravertebral foramen nerve root division, the motoneuron in cornu anterius medullae spinalis necrosis rate reaches 20%-30%, and most of the residual neurons are pathologic. The regenerated fibers manifest as insufficient dynamic power and incomplete development, making no sense for the recovery of end organ function. Therefore, the exact mechanism of the recovery of biceps brachial muscle demands further study.
Xuan
Zhaopeng
Z
Department of Hand and Foot Surgery, First Hospital of Jilin University, Changchun Jilin, 130021, P.R. China.
Zhang
Xiaojie
X
Lu
Laijin
L
Liu
Zhigang
Z
D000714:Anastomosis, Surgical; D000818:Animals; D000870:Anterior Horn Cells; D001917:Brachial Plexus / Q000601:surgery*; D009416:Nerve Regeneration; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000473:pathology* / Q000503:physiopathology*