Phenol block of peripheral nerve conduction: Titrating for optimum effect.
OBJECTIVE
To verify the dose-response relationship in phenol nerve block and to determine the concentration and volume of phenol injectate required for effective nerve conduction block.


METHODS
Before-after, experimental study.


METHODS
A research institute laboratory.


METHODS
Seventy-one New Zealand white rabbits.


METHODS
Group I (n = 48) received tibial nerve block by perineural injection (phenol, n = 40; saline, n = 8), group II (n = 21) by submerging the nerve in phenol solution. The 6 subgroups of group I each received different concentrations (3%, 4%, 5%) and volumes (0.1mL, 0.2mL, 0.3mL). The 2 subgroups of group II received 3% (n = 8) and 5% (n = 13) phenol.


METHODS
Compound muscle action potential (CMAP) and tension of triceps surae muscles by electric stimulation of the sciatic nerve were measured preintervention and at day 1, and weeks 1, 2, 4, and 8 postblock. Histologic studies were performed on 2 animals from group I.


RESULTS
Two rabbits in group I died before results were obtained. In the remaining animals, CMAP amplitude reduced significantly (p <.05) as the volume of 5% phenol solution increased from 0.1mL, 0.2mL, to 0.3mL. A high concentration of phenol produced a more pronounced conduction block; however, no significant (p =.0589) difference existed among the 3 concentrations. Submerged tibial nerve had a greater degree of conduction block than perineurally injected nerve. Depth of the degeneration area in nerve fascicle varied with distance from the injection point.


CONCLUSIONS
The nerve block effect of phenol can be titrated by adjusting the concentration and volume of phenol solution if the technique of application and localization of a block site are standardized.
Sung
D H
DH
Department of Physical Medicine and Rehabilitation, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul National University College of Medicine, Korea. dhsung@smc.samsung.co.kr
Han
T R
TR
Park
W H
WH
Je Bang
H
H
Kim
J M
JM
Chung
S H
SH
Woo
E J
EJ
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D007267:Injections; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation* / Q000503:physiopathology; D009407:Nerve Block / Q000379:methods*; D009410:Nerve Degeneration / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology; D009431:Neural Conduction / Q000187:drug effects*; D019800:Phenol / Q000008:administration & dosage*; D011817:Rabbits; D012597:Sclerosing Solutions / Q000008:administration & dosage*; D013979:Tibial Nerve / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D017186:Titrimetry / Q000379:methods*
D012597:Sclerosing Solutions; D019800:Phenol