September 9, 2008

LOCAL ANALGESIA/ANESTHESIA VIA ICE THERAPY^©

Lyn Paul Taylor, A.A., B.A., M.A., R.P.T.

(Editing Assistant and Computer Consultant: Joanna Soon, B.S.)

Ice therapy, the application of ice or other coolants (cryotherapy), may be used to provide relief of localized pain arising in the musculoskeletal system, as well as providing local anesthesia (numbing) of dermal (skin) layers.  Pain relief (analgesia) from cryotherapy results from (1) the elevation of the pain threshold as cooling affects pain receptors and sensory fibers in the involved tissues, (2) slowing of the inflammatory process, and (3) the reduction of muscle spasm.

Local anesthesia results from unrelieved cooling, through hyperstimulation and the eventual overwhelming of the sensory nerves and sensory nerve endings in the skin and muscles below.  Each class of sensory receptor will fire, in turn, as they are cooled and their individual resistance to the cooling is exceeded. They will continue to fire as cooling continues until fully exhausted and anesthesia occurs.

The most commonly used mode of cryotherapy is the ice pack.  It is easy to apply to most treatment sites, requires little time or equipment to make, and places a minimal demand on the practitioner's time during treatment.  Local anesthesia is usually produced by a crushed-ice pack in 10 to 12 minutes.

It should be noted that an ice bag is a poor substitute for a crushed-ice pack (see ICE THERAPY), if anesthesia is desired, since it generally doesn't get the skin cold enough, though it may be effective for providing some local analgesia.

The use of cryotherapy to produce analgesia or anesthesia is most remarkable when used in the acute phases following traumatic injury, providing almost immediate relief from the excruciating pain of joint sprain or strain, muscle spasm, contusion, and muscle strain.  The relief of pain, while comforting to the recipient, may also allow the practitioner the opportunity to use treatment techniques that might otherwise be painful (soft tissue manipulation and taping are examples).  Additionally, cryotherapy may have the effect of slowing down or inhibiting the pathological processes of injury, including inflammation.

[See ICE THERAPY, Precautions]

References:

A.E. Grant, "Massage with Ice (Cryokinetics) in the Treatment of Painful Conditions of the Musculoskeletal System," Arch Phys Med & Reh, vol. 45, May 1964. Pp. 233-238

L.R. Haldovich, W.J. Personius, H.P. Clamann, R.A. Newton, "Effect of Fluori-Methane Spray on Passive Hip Flexion," Physical Therapy, 61:2, February 1981. Pp. 185-190

J.F. Lehmann, Therapeutic Heat and Cold, Williams and Wilkins, Baltimore, Md., 1982. Pp. 563-602

S. Michlovitz, S.L. Wolf (Ed.), Thermal Agents in Rehabilitation, F.A. Davis, Philadelphia, Pa., 1986. Pp. 73-97, 263-275, 277-294

R.A. Newton, "Effects of Vapocoolants on Passive Hip Flexion in Healthy Subjects," Physical Therapy, 65:7, July 1985. Pp. 1034-1036

L.P. Taylor, T. Hui, The Taylor Technique of Soft Tissue Management, Inflammation: Evaluation & Treatment, 2002.  p. 38

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