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Cryotherapy
  Cryotherapy is a broad term that
covers a number of specific techniques, including ice packs, cold gel
packs, ice massage, ice immersion, and cold whirlpool.
Initially,
after application of an ice pack, the patient feels cold, which
progresses to burning, warming sensation. Aching, tingling, and finally
numbness follow.
First response is constriction of arterioles
and venules (within 15 minutes or less). Blood flow to area decreases,
and body attempts to conserve heat. The vasodilation can be
cold-induced after initial period of vasoconstriction when cold is
maintained for longer than approximately 15 minutes or when temperature
is reduced below 10° C.
A period of alternating vasodilation and
vasoconstriction also may occur, known as "hunting response." This
response is most predominant in apical areas where arteriovenous
anastomoses are located in skin and has been shown to be absent in
deeper tissues. After cold is removed, temperature rises in adjacent
body parts.
Additional effects of cryotherapy
Decrease in local metabolic rate.
Decreased conductivity of pain receptors and nerves (when cooled to 10° C).
Decreased tissue extensibility.
Spasticity
reduction results from decrease in gamma motor neuron activity by
excitation of cutaneous afferents. It also acts by decreasing
afferent-spindle discharge.
Finally short applications of cold can be effective adjunct to therapeutic exercise by stimulating muscle function.
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