| BackgroudSubarachnoid block anesthesia can often cause a kind of neuropathic pain named transient neurologic symptoms, and the incidence of which is positively correlated with the utilization of hyperbaric local anesthetics. Research found that high permeability glucose solution can cause nerve conduction velocity slower, nerve fiber regeneration etc pathological changes. In this research, we take SD rats as experimental animals to investigate the influence of high permeability sugar solution to rat behavior and rat dorsal root ganglion pathology. Then to discuss the hidden danger of the clinical subarachnoid block anesthesia application hyperbaric local anesthetics, to seek a more safety and normative subarachnoid block anesthesia method.Methods70 adult SD rats were used, male and female. Establish animal model which to set the tube under the rat spinal cord arachnoidea. Observe the rats which were points cage bred for 72h, then divide randomly those rats without neurological damage with horizontal wire test into 3 groups. Each group were sheath noted 20ul NS, 5%GS or 10%GS, and then were divided into four subgroups according 2h, 24h, 48h and 72h. Horizontal wire test, thermal withdrawal latency and the change of body weight were used to test the recovery of motor function and common situation as an index of behavioral influences. Executed and separated rat dorsal root ganglions at lumbar 4-5 segments. Four subgroups were colored with hematoxylineosin staining and Bartonella dyeing. Observe cell structural changes of dorsal root ganglions under light microscopy over time and glucose concentration change. The 2h subgroup were also observed ultrastructure changes of dorsal root ganglion under electron microscopy.ResultsOnly 63 in 70 rats involved in final result analysis. One rat died on sheath cathetering.1. Horizontal wire test result: Six rats were abandoned because appearing nerve damage so that failed horizontal wire test after subarachnoid catheter. All the rest 63 rats passed the horizontal wire test after sheath medicine.2. Thermal withdrawal latency changes: After cathetering, the thermal withdrawal latency of all the rats was obviously prolong than the thermal withdrawal latency before cathetering, and this change was statistically significant (P<0.01). After sheath medicine, the thermal withdrawal latency of 10%GS group was prolong according to the other two groups and itself before sheath medicine. But this change showed no statistically significant (P>0.05).3. Body weight changes: The rat body weight changes really existed in and between the groups through three consecutive days'observation after catheter different medicine. But the differences between any two groups showed not statistically significant with T test (P>0.05).4. Pathological structure changes: After HE dying, the dehydrationrate of 5%GS group and 10%GS group showed obviously significant higher than NS control group under light microscope. And so is the 10%GS group according to the 5%GS group. However, it showed not significant difference among the three group after 24h sheath medicine and the dehydrationrate of any experiment group is significant lower than itself after 2h sheath medicine. After 48h and 72h sheath medicine, the dehydrationrate among three groups seem not to be distinctly different. The damage performed as dorsal root ganglion cell obvious dehydration, cell shrink, separating from satellite cells around, karyopycnosis, nucleoli disappear, Nissl bodies reduce and light dye. The dorsal root ganglion cells showed a tendency of apoptosis. After 24h, the dehydration of DRG cells eased, and cells showed compensatory swelling on 48h. After 72h, the DRG cells mainly resumed normal. Under electron microscopy, the NS control group performed mild nerve injury, and the 5%GS group showed mild to moderate nerve injury. But the cells in 10%GS group were severely damaged like mitochondria swelling, vacuolar degeneration, crest disappeared; endoplasmic reticulum swelling expansion, lysosome increased, myelin swelling osteoporosis, or even disintegration, organelle inside unclear and partly neuraxial stripping.ConclusionThe high permeability glucose solution caused damage to both dorsal root ganglion cells and cell fiber in rats. The damage appeared only after 2h sheathing and tend to reverse in 24h, but not the significant behavioral changes. The characteristics of this damage basicly conformed to transient neurologic symptoms caused by subarachnoid anesthesia, but not exactly the same. It needs more research and experiment. |
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