Objective To study the functional change of nerve trunk after removing the partial bundles of ulnar nerve, to propose the concept of functional reserve of peripheral nerves and to investigate the functional reserve quantity of peripheral nerves. Methods Two hundred and twenty SD rats (male or female), aging 3 months and weighing 300-350 g, were randomized into the experimental group and the control group (n=110 per group). And the experimental group wassubdivided into group 1/8, group 1/4, group 1/3, group 1/2 and group 2/3 according to the resection portion (n=22 per group). In the experimental group, the section of the lowest level on ulnar nerve trunks was exposed, and a certain portion of its bundles was separated and cut, while in the control group the bundles were only separated without resection. The general condition of all rats was observed, and the motoneurons in cornu anterius medullae spinal is were detected at 1 week, 2 weeks and 2 months after operation. The neuro-electrophysiology and the function of dominated muscles were detected at 2 weeks, 2 months, 3 months, and 4 months after operation. Results All the rats survived without infection and obvious ulcer in the l imbs. The number of motoneurons in cornu anterius medullae spinal is in various experimental subgroups witnessed no obvious changes (P gt; 0.05). The superstructure changed obviously at the early postoperative stage in group 1/2 and group 2/3, but restored well at 2 months after operation. For the latent period of evoked potential, there was no significant difference between the various experimental subgroups and the control group at each time point (P gt; 0.05), but there was a significant difference among the various experimental subgroups when compared the time points of 2, 3 and 4 months to that of 2 weeks (P lt; 0.05) and no statistically significant difference at other time points (P gt; 0.05). For the wave ampl itude of evoked potential of motor nerves, the maximum wave ampl itude and the persistence time of the dominate muscle, there were significant differences between the various experimental subgroups and the control group at each time point (P lt; 0.05), and there were significant differences among the various experimental subgroups when comparing the time points of 2, 3 and 4 months to that of 2 weeks (P lt; 0.05) and no statistical significance at other time points (Pgt; 0.05). Conclusion The functional reserve of the ulnar nerve withoutcompromise accounts the 1/3 of the whole trunk diameter.
Objective To evaluate the feasibil ity 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 theproximal stump immediately after cutting off the brachial plexus extravertebral foramen nerve root division. The right C5-7nerve 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 lt; 0.05), but no significant difference at 6 months (P gt; 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 swell ing to shrinkage, dyeing nerve fibers increased, neural axone was thin and myel in sheath was sl ightly stained at each time point in experimental side. The number of motor neurons in cornu anterius medullae spinal is 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 thatthe 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 myel in sheath and the more massive of axon at 6 months after operation. And there was almost no myel in and axon stained in musculocutaneous nerve. Conclusion In the rat model of brachial plexus extravertebral foramen nerve root division, the motoneuron in cornu anterius medullae spinal is 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.