Ethyl alcohol is one of the most commonly used neurolytic agents in the treatment of chronic intractable pain of various causes and the spastic muscular diseases.
It is applied to the nerves or plexuses via direct injection, such as celiac plexus block or indirect route, such as subarachnoid injection.
Like other chemical neurolytic agents, ethanol has several disadvantages and adverse effects and so limitation to its use. Ethanol neurolysis. also, is frequently not permanent in action and so performed repeatedly at various intervals. There were some efforts searching for optimal concentration of the ethanol and optimal interval to repeat the neurolytic block but still lack of data.
The authors experimentally observed the morphological changes of the rat sciatic nerve four weeks after perineural injection of 50%, 75% and 100% ethanol through the light and electron microscope and compared the results with those of 0.9% normal saline in each ten cases. Also we observed other adverse effects. the skin change and muscular weakness.
The results are as follows .
1. Three of ten cases in the group of 100% ethanol showed skin redness and one of them showed skin ulceration, discoloration and at last skin slough after three weeks.
2. Complete loss of motor function was not seen in any case. But six cases in the group of 100% ethanol. three cases in the group of 75% ethanol. and t재 cases in the group of 50% ethanol showed partial loss of motor function, such as limping gait. They all recovered after two weeks. but a case in the group of 100% ethanol did not even after four weeks.
3. In the light microscopic findings, four cases in the group of 50% ethanol and all cases in the group of 75% and 100% ethanol showed typical wallerian degeneration but the degree and extent of the degeneration were dose-dependent.
4. In the transmission electron microscopic findings, relatively large myelinated axons survived in the group of 50% ethanol, but they were all destroyed in the group of 75% and 100% ethanol.
5. The regeneration of the injured axons were observed at their various stages.
In conclusion, 100% ethanol should be used clinically with special caution about the loss of motor function and skin injury. Because the integrity of the basement membrane of Schwann’s cell must be maintained by the perineural injection, the regeneration of the injured nerves take place with certainty. But it is difficult to find out the optimal time for repeated neurolysis due to the variability of duration of regeneration.
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