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the therapeutic use of cold.
Since ancient times ice packs and sheets soaked in water have been used in treating disease. Moderate cooling (without causing freezing) is used to reduce inflammatory phenomena, stop bleeding, relieve pain, and decrease swelling. The effect of cold is explained by reflex reaction (the constriction of blood vessels and the slowing of blood flow) or by lowering of the metabolism in the given region. Cold (the application of ice bags) is used for a variety of inflammations (in the region of the gall-bladder, appendix, stomach, pancreas), bruises, and fractures. Application of ice bags to the affected area or swallowing pieces of ice is prescribed for pulmonary, nasal, and gastrointestinal bleeding. Dressings with chilled alcohol are applied to burns. Specially designed rubber helmets through which cold water constantly flows are worn to control edema by individuals suffering from brain concussions or contusions. In the case of short operations (for example, the lancing of abscesses or phlegmons), anesthesia is achieved by spraying the tissues with ethyl chloride, removing the heat, freezing them, and lowering their sensitivity. Cooling the body generally, or hypothermia, is used in operations on the heart, major blood vessels, and brain.
V. A. DUMCHEV
One of the most important branches of cryotherapy is cryosurgery, a new field that uses low temperatures to destroy organs and tissues. Attempts to use cold to destroy tissues were first made in the 1940’s, when the American surgeon T. Fay subjected malignant tumors in inoperable patients to prolonged chilling and obtained noticeable, although brief, remissions. Many dermatologists use local freezing (mostly with carbon dioxide) for certain diseases and malignancies of the skin.
It has proved to be much more difficult to freeze tissues locally deep within the body. Chilling mammalian tissues to the freezing point results in their total and irreversible necrosis. This is a consequence of the dehydration of the cells implied in the formation of ice crystals (both within the cells and in the extracellular fluid), the sharp increase in the concentration of electrolytes within the cells (”osmotic shock”), the mechanical injury to the cellular membranes and organelles by the ice crystals, and the cessation of the blood flow in the region frozen.
The local refrigeration of deep structures in the human body became possible with the creation of suitable apparatus. As a result, cryosurgery has been introduced into various medical fields. Tests with Freon and other refrigerants have shown that liquid nitrogen (boiling point, −195.8°C) is the most suitable for cryosurgical purposes.
Cryosurgery is widely used in brain operations. It was used for the first time in 1961 in the USA in stereotaxic operations in order to create a strictly local focus of destruction (7–9 mm) in the deep subcortical structures of the brain. In 1962, the Soviet scientists A. I. Shal’nikov and E. I. Kandel’ constructed an original instrument for the cryogenic destruction of deep structures in the brain. Its principal element consists of a thin metal tube, or cannula, with a reservoir of liquid nitrogen. The tip of the cannula, stereotaxically guided to the appropriate structure, produces a temperature sufficiently low to turn the prescribed area of brain tissue to ice. Since the thin cold-conductor inside the cannula is insulated against heat by a deep vacuum (10−7 mm Hg), the cannula itself remains warm; a temperature of −70° is created only at the tip (2 mm long). A ball of ice, 5–9 mm in diameter, forms in its vicinity only. The nitrogen is then boiled away and the ball thaws; the frozen brain tissue, thawing in turn, then dies.
Another model of this instrument, developed in 1970, is capable of freezing a substantial amount of tumor tissue (as much as 50–55 mm in diameter).
Cryosurgery is used in stereotaxic operations on the brain for parkinsonism, torsion dystonia, athetosis, spastic torticollis, and severe pain. Cryodestruction of the normal pituitary is effective against metastases of certain types of cancer. The freezing of pituitary tumors is a promising procedure for acromegaly and Itsenko-Cushing syndrome. Promising results have been obtained in the cryodestruction of tumors of the cerebral hemispheres. Cryosurgery is also used in the treatment of certain eye diseases (retinal detachment, intraocular tumors) and to remove tonsils, nasopharyngeal polyps, tumors of the nose, and prostatic adenomas.
E. I. KANDEL’