Phenol Nerve Block

Excerpt

Neurolysis is the temporary denervation of a targeted nerve or nerve plexus by directed infiltration of chemicals, obliteration from cryotherapy, or radiofrequency ablation. The first report of chemical neurolysis for the treatment of pain was made in 1863 by Luton who administered irritant chemicals subcutaneously into painful body areas and claimed substantial benefit to those with sciatic neuralgia. It was not until 1926 that the use of phenol as a neurolytic agent was described by Doppler et al., followed by a description of intrathecal injection of phenol in 1955. In 1959, Nathan et al. and Kelly et al. described the earliest use of phenol for spasticity and reported relief following intrathecal injections.,

Phenol is a chemical composite agent that is comprised of carbolic acid, phenic acid, phenylic acid, phenyl hydroxide, hydroxybenzene, and oxybenzone. It denatures protein readily and may cause denervation when injected near neural structures, leading to loss of cellular fatty content, separation of the myelin sheath from the axon, and axonal edema. Phenol’s effects may be a combination of both neurotoxicity and ischemia. Histologic specimens have demonstrated non-selective nerve destruction, muscle atrophy, and necrosis with phenol injections.,

Currently, neurolysis is most often performed with ethanol and phenol, although hypertonic saline, glycerol, ammonium salt solutions, and chlorocresol have also been used in the past.