CryosurgeryCHAPTER 1

Cryosurgery is the term used to describe procedures that achieve surgical outcomes by using freezing temperatures. Tissue destruction and healing by secondary intention usually follow, resulting in tissue/structural change and remodeling. Low temperatures are obtained by cryogens, usually molecules that exist as gases at normal room temperature. They generate the cooling effect by absorbing heat for expansion, evaporation and/or boiling. Non-destructive use of cold temperature to modify disease is termed cryosurgery.

Cryotherapy has a long history. ¹ The benefits of cold have been appreciated past many thousands of years. Ancient Egyptians and later Hippocrates used cold for its analgesic and anti-inflammatory properties. In early 18th century, James Arnott, an English physician, used mixture of salt and ice to achieve extreme cold in the palliation of tumors.² The modern cryosurgery began with the discovery of the liquefaction of gases. In 1898, Dewar developed the vacuum flask for storage of liquid gas. The first cryosurgeon in Modern Medicine was an American Dermatologist, White, who used cotton-tipped applicators to apply liquefied air to treat certain skin conditions. Pusey reported use of carbon dioxide snow for cryotherapy.³ Allington first used liquid nitrogen as a cryogen in the year 1950.

Several terminologies have been used. They include cryotherapy, cryocautery, cryocongelation, and cryogenic surgery, but cryosurgery and cryotherpy are in vogue and often used interchangeably. However, some experts restrict the term cryotherapy for non-destructive treatment of skin conditions, such as acne, alopecia areata.⁴

Commonly used cryogens are:

Mammalian/ human tissues function optimally in a normal range of temperature, which is maintained by elaborate mechanisms. Extreme variations in temperature progressively results in dysfunction and then death.

The amount of destruction obtained by cryosurgery is determined by the amount of tissue that attains the temperature that is destructive for it. For skin the target temperature is in the region of –50°C (to attain total destruction, important for treating malignant lesions of basal cell carcinoma and squamous cell carcinoma, etc.)

Gaseous cryogens are stored in metal cylinders as compressed gas (Fig. 1.2). Liquid nitrogen is stored in specialized insulated flasks (Dewar's) with inbuilt internal pressure equalization mechanism.

Special steel alloys are used in transferring equipment that can withstand abrupt lowering of temperatures without fracturing.

Needle thermocouple solid state thermometers reading from –200ºC to 40ºC (not available in India).

The patient is explained the procedure and the necessity to make the site of operation accessible, visible and held steady. The patient is then made comfortable and any anxiety allayed and analgesic, if felt necessary, administered and given time to take effect. The area (field) is cleaned with iodine/alcohol/acetone and draped. Special care is taken to protect surrounding area with insulation, if spray cooling is being used, by sterile gauze pad covered with surgical tape. If cryoprobe is being used, the appropriate sized, sterilized, cryoprobe is selected and layered thinly with petroleum jelly, as is the lesion surface to allow smooth uniform contact.

Cooling is applied (either by spray or probe) till ice crystals appear on the lesion and for a few millimeters around the probe (or the cooled target area) and this is maintained for 30 to 60 seconds (holding time).8

The frozen lesion is then allowed to thaw and get back spontaneously to room temperature after holding the freeze for 30 to 60 seconds. The freeze thaw cycle may need to be repeated again, particularly to ensure complete destruction of malignant lesions. The probe or cone that gets attached to the lesion while freezing should be allowed to spontaneously work loose while thawing and must not be pulled away earlier.

The patient is explained that subsequent to the freezing there will be some pain, blistering and peeling, after crust formation, over the lesion in the next couple of weeks. The patient may be prescribed an non-steroidal anti-inflammatory drug (NSAID) medication for a few days after cryosurgery and some mild antibiotic or antiseptic cream to apply daily after a bath/wash. The patient may be asked to come for follow up, weekly, for evaluation of results, assessment of healing and repeat therapy, if necessary. On exposed, trauma prone areas, light sterile gauze dressing in the initial few days, over antiseptic/disinfectant may need to be prescribed till the lesion dries.

Various techniques for use of liquid nitrogen described above involve freezing of the lesion from the surface. With these techniques, freezing up to a depth of 1 to 2 cm can be achieved. Moreover, in these procedures, the major brunt of the lethality falls on the surface epithelium. Therefore, for lesions located in dermis and subcutis, these techniques may not always be successful. To overcome this drawback, Weshahy developed a new technique of intralesional cryosurgery.⁶ He introduced one or more needles into the skin from one end of the lesion, which run through the deeper part of the lesion and surface on the opposite border. Liquid nitrogen is the passed through the needle, which exits through the other end. During its passage through the needle, liquid nitrogen freezes the deeper tissue, with a relatively less destruction on the surface.⁷

Assembling the intralesional cryosurgery device requires a small liquid nitrogen Dewar cylinder with spray tip, an intravenous drip-set, an adhesive tape and single use lumbar-puncture (LP) and/or hypodermic needles. The latex rubber tube with its attached plastic tube is removed from the drip-set and one of its narrow parts is cut. It is then connected to the spray tip and fixed tightly with adhesive tape (Fig. 1.3). The tip of the plastic tube fits snugly on to the single use injection or LP needle.

Absolute contraindications to cryotherapy are relatively few, and include the following:

Relative: Dark skinned individuals are more likely to have permanent hypopigmentation/depigmentation.

Cryosurgery is a useful modality for the treatment of certain infectious diseases of skin, such as condyloma accuminata, verruca vulgaris, molluscum contagiosum, Kaposi's sarcoma, chromoblastomycosis and Leishmaniasis.⁸ The advantage of cryosurgery is that it is a bloodless procedure, therefore, can be used safely in patients with HIV or hepatitis B infections. Certain modifications have been used for treatment of infectious lesions. Disposable hypodermic needles of various gauges can be used in place of probes. The needle can be attached with to cryoprobe stem with a plastic tube (Fig. 1.3). Otoscope cones may be used to limit lateral spread of the cryogen. Only small, thin lesions of Kaposi's sarcoma on the face, ear, hands, and forearms should be treated with cryosurgery. A cure rate of 80 percent can be achieved, though cosmetic improvement occurs only in 50 percent of the patients.⁹

For common warts, weekly cryotherapy produced more rapid cures, but the overall cure rate depended on number of treatments. Plantar warts require two freeze-thaw cycles of 30 to 60 seconds and paring before freezing to improve the cure rate.¹⁰,¹¹ Periungual warts require 10 to 15 seconds freeze using cryospray. A 2 to 3 mm halo surrounding the wart should be achieved in order to bring about the complete eradication of the wart.¹² Irreversible matrix destruction can occur with prolonged freezing, which may lead to permanent nail atrophy.¹³

Multiple skin tags can be easily frozen with a cotton bud or a spray technique, however, care should be taken to avoid freezing the surrounding skin, which may lead to unsightly pigmentary changes.

These superficial lesions are easily treatable with a single freeze of 5 to 10 seconds. Bulky lesions of seborrheic keratosis may require more freeze-thaw cycles of 10 to 20 seconds.

Cryotherapy has some role in cystic acne. Individual cysts can be treated with liquid nitrogen spray for 5 to 10 seconds. A small Eschar is formed which dries in about a week.14

Cryosurgery has been used for years in the treatment of keloids. The therapeutic effect of cryosurgery in keloids depends on direct cell damage as well as on changes in the microcirculation. The resulting anoxia causes tissue necrosis and sloughing, followed by tissue flattening. Liquid nitrogen is the suitable cryogen. Freeze time varies depending on the characteristic of the individual lesion. Approximately 1 cm³ lesion requires 10 to 30 seconds freeze. Larger lesions require longer duration freezing and lesions on cosmetically prominent sites should be treated with a shorter duration freezing. Rusciani et al obtained good results in 73.8 percent of the lesions.¹⁴ Success rates are even more when cryosurgery is combined with intralesional triamcinolone injections. Many experts use cryofreezing to cause mild tissue edema enabling easier injection of intralesional steroids.¹⁵ However, there is a risk of permanent hypopigmentation, especially in patients with darker skin types. Many patients may not return for follow-up cryosurgery because of the post-operative pain, morbidity and slow healing.

Cryosurgery is an effective treatment modality for non-melanoma skin cancers. The procedure is done under local anesthesia. Preliminary curettage should be carried out and the lesion is treated with open spray technique using liquid nitrogen.

Recommended freezing time ranges from 40 to 90 seconds depending on the size and thickness of the skin cancer. The frozen area should extend at least 3 to 5 mm beyond the margin of the cancer. In most reported studies, the cure rate for non-melanoma skin cancers is more than 90 percent (Figs 1.4A and B).¹⁶,¹⁷