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Cryosurgery |
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Equipment: The coolants (usually nitrous oxide or liquid nitrogen) act via a cryoprobe and a tubing system. The probe tip is applied to the lesion with an intervening layer of lubricant jelly, this gives rise to an ‘iceball’, which is essential for success. Liquid nitrogen can also be directly sprayed onto the lesion.
Mechanism: Cell death and subsequent tissue necrosis by cellular disruption, dehydration, enzyme inhibition, and protein denaturation follows application of extreme cold. Indirect effects include vascular stasis and an immune response. There is a curious lack of infection and scarring following cryosurgery.
Indications: 1. Vascular malformations (haemangiomas) 2. Areas of leukoplakia unsuitable for excision, and providing they have not undergone malignant change 3. Extensive hyperplastic lesions e.g. palatal hyperplasia under F/- dentures may respond 4. Viral warts 5. Mucoceles—in most instances 6. Superficial basal cell carcinoma—controversial in more aggressive malignancy 7. Following enucleation of keratocytes 8. Intractable facial pain—the freezing of peripheral nerves induces a period of analgesia which extends beyond the original post-op numbness
Technique: ¨ Warn the patient about the procedure, post-op oedema and a slough which forms over frozen sites. ¨ LA for larger lesions or if biopsy needed ¨ Select a probe-tip suitable for the lesion, overlap ice zones if the lesion is large ¨ Use KY jelly to improve contact between probe and tissue ¨ Usual freeze-thaw cycles around 1 minute, repeated at least twice ¨ Do not remove probe until defrosting has occurred ¨ Careful follow-up and check histology of the lesion, except when using cryoanalgesia
Limitations ¨ The treatment of frank malignancy by cryosurgery remains controversial ¨ No tissue available for histopathology investigation ¨ No way of determining adequate margins and depth of tissue destruction.
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Cryosurgery is the therapeutic use of extreme cold |
