What is the role of phenol in the treatment of spasticity?

Updated: Mar 01, 2018
  • Author: Krupa Pandey, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Answer

Phenol is inexpensive, easily compounded, and has an immediate onset of action. It is injected, usually in a 5% concentration, near motor points in the affected muscle. A neurostimulator with a Teflon-coated needle electrode is used for guidance.

Gamma fibers are demyelinated for about 6 months, resulting in a less irritable, weakened muscle that can more easily be stretched.

Because 5% phenol injections do not cause permanent reduction in spasticity, a focus on obtaining functional improvements after injections is important.

Injections can be uncomfortable for some patients, and children may need to be sedated before injection. Possible adverse effects include pain and swelling at the site of injection. In a very small number of patients, dysesthesias may occur if injections are done near sensory-rich nerve branches.

If lengthening of a shortened muscle is desired, serial casting following injections may enhance effectiveness.

Intrathecal bolus injection of phenol

Jarret et al have reported that intrathecal bolus injection of phenol can reduce lower-limb spasticity. Twenty-five patients with advanced multiple sclerosis received 1.5-2.5 mL 5% phenol in glycerol at L2/3 or L2/4, and improvements were seen in the Ashworth score, spasm frequency, and pain, although the duration of the beneficial effect was not indicated. No serious adverse effects were reported. [23]


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