Cryotherapy

Cryotherapy is a guided and selective removal of the diseased tissue by low-temperature application.
For the treatment of multiple dermatoses, it is a simple, cost-effective, safe, and esthetically appropriate method.

An extensive range of skin disorders, including benign cancers, acne, skin lesions, viral infections, inflammatory skin conditions, infectious diseases, and some pre-malignant and malignant tumors, are reported in the treatment of cryotherapy.

There are many cryotherapy methods available, such as liquid nitrogen, nitrous oxide, and carbon dioxide, but the most widely used is liquid nitrogen.
The timed spot freeze (open spray and confined spray) technology, the use of cryoprobes, or the dipstick process, are some techniques for the application of cryotherapy.
The procedure is chosen according to the type of injury.
The process is carried out without anesthesia under aseptic conditions.

The amount of freeze-thaw cycles required can vary from injury to injury. To acquire effective reconstructive results with minimal complications, it is necessary to know the freeze period for and condition, the number of interventions required, and the interval between sessions.

Contraindications: The prescriber should be conscious of the absolute and relative contraindications of 

the operation, such as cold urticaria, cryoglobulinemia, Raynaud's disease, vascular collagen diseases,

In the current age, cryotherapy continues to hold a very significant role in a dermatologist's therapeutic collection, following the emergence of many emulative procedures such as radiofrequency or laser therapy.   

• It is a very secure, inexpensive, reproducible, repeatable, and simple bureau procedure. 
• It demands a short preparation span, 
• is a suture-free procedure with a limited risk of infection and 
• typically does not require anesthesia.

Cryotherapy can be conducted at any age, including in older patients with pacemakers with contraindicated electrocautery, patients with anticoagulants, patients allergic to anesthetic agents, patients with transmissible conditions such as human immunodeficiency virus (HIV) and hepatitis, during pregnancy and on most areas of the body. Even in difficult areas, it provides excellent curing levels, with outstanding cosmetic outcomes if done correctly. Despite all of these advantages, it is regarded by many dermatologists as a treatment of choice for both benign and malignant dermatoses.

Cryoablation mechanism: The deconstruction of tissue occurs as a result of the rapid transfer of heat from the tissue, causing tissue injury, vascular stasis, and occlusion and inflammation. A prompt removal of heat from the membrane to the cryogen occurs when the cryogen is sprayed, with ice forming in the extracellular compartment. The extracellular solutes are concentrated, creating an osmotic gradient, with extracellular fluid movement and concentration of solutes inside the cell, causing cell damage. The ice crystals physically damage the cell membrane too.  Besides, there is intracellular ice development, which destroys organelles such as mitochondria and reticulum endoplasma. Owing to cold temperature, significant vasoconstriction and endothelial damage is leading to platelet aggregation and microthrombi formation, causing ischemic tissue necrosis. In response to cell death, there is inflammation, which causes further destruction. Cryodamage has a differential sensitivity of any cell or tissue, with melanocytes and deeper layers of epidermal cells varying in responsiveness and being cryo-resistant to dermal collagen. 

Physician qualification: Cryodamage has a differential sensitivity of any cell or tissue, with melanocytes and deeper layers of epidermal cells varying in responsiveness and being cryo-resistant to dermal collagen. 

 
Facility: Cryotherapy can be performed with a high degree of aseptic protection in the office procedure room of a physician or in the minor venue. It is ideal to have a fully fitted minor operating theatre with strong lighting, sufficient minimum sterilization, and storage.    

1. Cryogun/cryogen spray canister: it is a portable,lightweight, hand-held device with a controllabletrigger to begin and end cooling.
2. Cryospray nozzle, cryoprobes, spray tips, neoprene,or polystyrene cones.
3. Cryoprobes: they are available in various shapesand sizes and get attached to the cryogen. They arecooled by the spray of the cryogen.
4. Cryogen storage device: they are metal cylinders/containers that store gaseous cryogens ascompressed gas and have an inbuilt internalpressure equalization mechanism, e.g., Dewar's gascontainer. The cryogen is transferred to the cryogunbefore the procedure by a siphon or by tilting thecontainer to pour the cryogen into the gun via afunnel. Insulated gloves must be worn whiletransferring the cryogen. e.g., Brymill cryogenicsystem.
 

Counseling and consent: 

The patient obtains a written informed consent after describing the treatment, the expected outcomes, the risk of recurrence, and other clinical complications. The consent form will state the possibility of temporary post-inflammatory blister development and modifications in pigmentation.

History taking and examination:

A comprehensive history of the general medical condition, earlier diagnosis with results obtained for the disorder, and whether it is a chronic or persistent lesion is taken. History of sensitivity to cold, cold urticaria, Raynaud's phenomenon, or insufficiency of the vascular system can be reported. Physical examination should be performed to determine the patient's skin type, lesional characteristics such as scale, margin, position, distance, biological activity and approximation to superficial nerves and previous treatment sites.

Pre-operative preparation: 

The surface to be treated with spirit or povidone-iodine is adequately exposed and thoroughly washed. Intralesional or topical anesthesia is often not required.
It should be used for malignant lesions since longer freezing time can result in extreme pain to ablate deeper malignant tissue.
An anxious patient is consulted and may be given an analgesic or antianxiety medication. The natural skin around can be coated to avoid spraying of surrounding areas. Sites like eyes, nares, and ears need to be covered by gloves, gauze, or padding.
 

Different methods of applying the cryogen to the skin lesion include:

• timed spot freeze technique
• open spray technique
• confined-spray technique
• use of cryoprobe
• dipstick method
• histofreezer
• post-treatment care

• vascular lesions
• benign tumors
• pigmented lesions
• viral infections
• inflammatory dermatoses
• infectious dermatoses
• pre-malignant and malignant tumors