Cryotherapy or ice therapy is the application of cold to the body tissues after injury. This practice is as old as medicine itself. Nowadays, local cold application may be applied by the use of various forms of ice or frozen gel packs, or by evaporation of volatile fluids from the skin.Often skin temperature is reduced to 10 C°.

A. Physiological Effects of Cold Application Circulatory Response The initial skin reaction to cooling is an attempt to preserve heat. It is accomplished by an initial vasoconstriction. This haemostatic response has the effect of cooling of the body part. After a short period of time, the duration depends on the area involved, a vasodilatation follows with alternating periods of constriction and dilatation. This reaction of “hunting” for a mean point of circulation is called “Lewis’s Hunting Reaction”. During the vasodilatation, the arteriovenous anastomosis is closed, thus causing an increase blood flow through the capillaries. This is beneficial in the treatment of swelling and tissue damage.

Physiotherapeutic Uses of the Circulatory Effect: The initial vasoconstriction is often used to limit the extravasations of blood into the tissues following injuries (e.g. sports injuries). Ice therapy is then usually followed by some forms of compression bandage. The alternate periods of vasoconstriction and vasodilatation affect the capillary blood flow and it is across the capillary membrane that tissue fluid can be removed from the area and returned in the systemic circulation. Increased circulation allows more nutrients and repair substances into the damaged areas.

Thus ice therapy is very useful in removing swelling and accelerating tissue repair. i.e. ice cubes massage may be used to accelerate the rate of repair of pressure sores. The reduced metabolic rate of cooled tissues allows cooled muscle to contract many more times before fatigue sets in.

Neural response The skin contains primary thermal receptors. Cold receptors are several times more numerous than warm receptors. The cold receptors respond to cooling by a sustained discharge of impulses, the rate of which increases with further cooling. The rate of conduction of nerve fibers in a mixed (motor and sensory) peripheral nerve is reduced by cooling. The first fibers affected by gradual cooling are the A fibers (myelinated) and eventually at very low temperatures the B and C fibers (non-myelinated) are affected. In practice, motor nerve paralysis is never produced by ice.

Excitatory Cold Mechanism When cold is applied in an appropriate way on the skin, ice can be used to increase the excitatory bias around the anterior horn cell. Combined with other forms of excitation (brushing, tapping,…) and with the patients’ volitation, this can often produce contraction of an inhibited muscle (only with intact peripheral nerve supply). This effect can be used when muscle are inhibited postoperatively or in the later stages of regeneration of a mixed peripheral nerve

B. Uses of Ice Therapy Reduces pain. Reduces spasticity. Reduces muscle spasm. Reduces swelling. Promote repair of the damaged tissues. Provide excitatory stimulus to inhibited muscles.

Reduction of Pain Pain reduction is one of the major effects of ice application which has been used for many years. The probable mechanism is that by the stimulation of cold receptors, impulses will be send back which will pass into the posterior root of the spinal cord. These impulses, arriving through large diameter nerves, effectively block out any other (pain) impulses attempting to access the spinal cord (pain gate theory). This reduces the pain temporarily. For permanent pain relief, positive physiotherapy (strengthening, mobilization) has to be given during this period of transient pain relief.

Reduction of Spasticity Spasticity is the pathological state of increased muscle tone resulting from damage to the upper motor neurons. The small anterior horn cell from the higher control of extrapyramidal system and fires spontaneously at an increased rate. The net result of this is ultimately to increase tone in the extrafusal muscle fibers, when the hypertonic spastic state appears.

Spasm is a normal response to injury or pain and is manifested as an increase in muscle tone in a specific area with the apparent aim of limiting movement and further damage. However the amount of spasm is often exceeding and the sustained contraction of muscles will in turn start to produce pain, often resulting then in more spasm.

The mechanisms by which cold reduces spasticity and spasm are probably: the reduced velocity of nerve conduction. the depressed sensitivity of receptors such as the muscle spindle.

These structures are fairly deep and it would take several minutes to produce a sufficiently low temperature to affect them. As it was clinically demonstrated that the reduction of spasm and spasticity occurs within 30 seconds of ice application, the reaction to cooling can only be at the superficial tissues at the skin. The skin stimulus produced by cold must have an effect on the general level of excitation and inhibition in the region of the anterior horn cells. Once spasm and spasticity have been reduced, more long-time treatment is given in order to sustain the condition. In the case of spasm, active movements are used to break down the vicious circle of pain-spasm- more pain- more spasm. With spasticity, the technique will depend upon the preference of the physical therapist.

Techniques of Application of Cryotherapy The way which ice is applied will vary according to the required effects. It may be applied in the following ways: –Ice towels –Ice packs –Immersion –Ice cube massage –Excitatory cold ( quick ice) –Ice spray –Cold gel

D. Contraindications to Ice Treatment: Cardiac Conditions Psychological: Peripheral Nerve Injuries Vasospastic Disease Peripheral Vascular Disease Cold Sensitivity