After localization of electrically sensitive points in hypertonic muscles, it was possible in all but 20 of 394 muscles in 95 patients to achieve significant relaxation resulting in improved function or posture with intramuscular chemical neurolysis. Injections of dilute phenol solution in small amounts were used. The injections can be repeated, and relaxation has been maintained by a single series or multiple series of injections as long as a year to 17 months. Relaxation persisted six months or longer in 60% of the muscles injected and four months or longer in 84%.
Halpern D, Meelhuysen FE. Duration of Relaxation After Intramuscular Neurolysis With Phenol. JAMA. 1967;200(13):1152-1154. doi:10.1001/jama.1967.03120260048007