Objective: To evaluate the axonal degeneration after nerve block with phenol and ethanol injection into tibial nerve.

Method: Tibial nerves of thirty Sprague-Dawley rats were exposed. For the developement of neuropathic pain, the method of intraneural injection was performed. Five percent phenol, 90% ethanol or normal saline were injected into the epineurial sheath of tibial nerve at each group. The mechanical and thermal allodynia were evaluated in post- injection 1, 2, 3, and 4 weeks. The mechanical allodynia was evaluated by withdrawal response to 10 stimulations with von Frey hair. Thermal allodynia was tested by withdrawal response to 5 stimulations with acetone. Motor nerve conduction study was performed in post-injection 1, 2, and 4 weeks.

Results: In behavioral test, the experimental group exhibited increased withdrawal response to mechanical and cold stimulation, but there was no significant difference between two groups, phenol and ethanol groups. In motor nerve conduction study, compound motor action potential amplitude loss were observed in experimental group, but there was no significant difference between two groups, phenol and ethanol groups.

Conclusion: These results suggest that axonal degeneration of ethanol is roughly similar to those of phenol block. (J Korean Acad Rehab Med 2002; 26: 470-474)

Objective: In the management of spasticity, intramuscular neurolysis with small amount of dilute aqueous phenol has proved to be a useful measure. But, considerable problem has taken place in utilization of phenol. This study was attempted to compare the effect of phenol and alcohol for the peripheral nerve blocking in the management of spasticity.

Method: Intraneural injection of 5% phenol, 50% alcohol and 90% alcohol solution carried out in each group of 10 rats. A total of 30 rat were injected and examined electrophysiologically before and after blocking the nerve (24 hour, 1 weeks, 2 weeks, 4 weeks, 8 weeks). The randomized one rat of each group was sacrificed for the histological examination of the sciatic nerve at every examined day.

Results: There was no difference of the distal latencies and amplitudes of compound muscle action potentials among the groups before injection. The latencies were prolonged at 24 hours post-injection and shortened at 1 week post-injection in all the groups. The amplitudes were markedly decreased at 24 hours post-injection and increased at 1 week post- injection and reached the pre-injection value at 8 week post-injection in all the groups. Histologic studies showed necrosis at 1 week post-injection and regeneration at 2 week post- injection in 50% and 90% ethanol groups. Phenol injection group showed necrosis at 4 week post-injection and regeneration after 8 weeks.

Conclusion: Our preliminary experience with alcohol for peripheral nerve blocking with encouraging result has been described.