Radio Surgery in Dermatology:
Radiofreqeuency Surgery is a versatile dermatosurgical procedure used for surgical management of skin lesions by using various forms of alternating current at an ultra high frequency. The major modalities in radiofrequency are electrosection, electrocoagulation, electrodessication and fulguration. The use of radiofrequency ablation in dermatosurgical practice has gained importance in recent years as it can be used to treat most of the skin lesions with ease in less time with clean surgical field due to adequate hemostasis and with minimal side effects and complications.
The basic equipment comprises a radiosurgical unit with a ground plate (dispersive electrode), foot switch and hand piece , It is provided with tungsten electrodes of various shapes and sizes with bendable shafts that are fitted into hand piece. A suction device for the evacuation of smoke in extensive surgery is also attached to the equipment. Radiofrequency uses various waveforms with the following tissue effects.
a. Electrosection: The fully filtered and rectified waveform applied to the tissues in biterminal fashion provides a smooth cutting current resulting in elecrosection. An electrode tip in the shape of a fine needle, wire loop, diamond, ellipse or triangle is advanced slowly through the tissue, causing a steam envelope to advance around the tip and producing a smooth cutting effect. The fully rectified current simultaneously produces cutting and coagulation. This waveform produces least amount of lateral heat spread with minimum tissue destruction.
b. Deep tissue destruction (electrocoagulation): The partially rectified waveform applied to the tissues in a biterminal fashion causes electrocoagulation. It gives instant homeostasis and is used in the treatment of the vascular lesions in which coagulation is primarily required.
c. Superficial tissue destruction (electrodessication and electrofulguration): This is achieved by the application of markedly dampened current to tissues in monoterminal or biterminal fashion. Fulguration causes the greatest amount of lateral heat spread and has a potential dehydrating effect. It causes the superficial tissue destruction through dehydration and surface carbonization. The electrode is held at a distance from the skin lesion in fulguration, while the tissue is touched with the electrode in desiccation.
Anesthesia for This Procedure:
Local anesthetic, i.e., lignocaine is administered before most radiosurgical techniques. The use of lignocaine with epinephrine further reduces blood loss, but the use of epinephrine at the tips of digits and the nose should be avoided. Another alternative is to use a eutectic mixture of local anesthetics cream that contains 2.5% lidocaine and 2.5% prilocaine. It is applied under occlusion to skin at least 1 h before the procedure to achieve topical anesthesia. Anesthesia may not be necessary for the electrosurgery of small lesions such as telangiectasias and small skin tags.
Intensity of the power setting:
The cutting of the tissue should be brisk and with the smallest electrode and power setting that is required to minimize the tissue damage and bleeding. The correct output power can be determined by starting at a low power and increasing the power until the desired outcome is attained (destruction, coagulation or cutting). In general, coagulation requires higher power settings than cutting, which requires higher power settings than desiccation or fulguration. The power settings for treating cutaneous lesions are generally low (10-20W).
Surface area of the electrode and contact time : An electrode of a small size causes less lateral heat spread and requires lower power setting. The cutting current procedures are best accomplished with a fine needle or wire electrodes. Movement of the electrode through the tissue should be continuous and fast to avoid build-up of lateral heat that causes tissue damage.The type of current selected : The selection of the waveform depends upon whether cutting or coagulation is the primary aim. This gives precise results with minimal tissue damage.
Presence of moisture : The presence of moisture on the surface of the tissue prevents charring. Therefore, the surface should be moistened with saline soaked gauze.
Waiting period : A waiting period of 10s is ideal between two passages of electrode used for cutting in the same surgical field. It allows adequate cooling and prevents cumulative heat damage.
Advantages of Radio Surgery:
Radio Surgery is a simple, safe procedure with wider applications. It causes less lateral heat spread and tissue damage and provides better control in comparison to electric cautery. The cutting mode of radiofrequency is more effective and versatile in comparison to the carbon dioxide laser. As hemostasis occurs simultaneously, the time required for the surgery is less. There are fewer side effects and complications. RFA can be easily combined with other surgical modalities such as cryotherapy and laser for treatment.
Dermatological Indications of Radio Surgery:
- Diagnostic: Skin biopsy, excision of cysts and abscesses.
- Infections: Verrucae, pyogenic granuloma and molluscum contagiosum.
- Metabolic: Xanthelasma, xanthomas
- Benign skin conditions: Freckles, dermatitis papulosa nigra, acne, skin tags, cherry angiomas, spider angiomas, naevi, trichoepithelioma, syringomas, apocrine hidrocystomas, stucco keratosis, papilloma, neurofibromas, cutaneous horn, keratocanthoma, rhinophyma, sebaceous hyperplasia and keloids.
- Senile skin conditions: Actinic keratosis, sebborheic keratosis and senile lentigenes.
- Malignant skin tumors: Squamous cell carcinoma, basal cell carcinoma, dermatofibroma sarcoma protuberans and carcinoma in situ lesions of the skin and orogenital mucosa.
- Nail procedures: Nail matrixectomies, surgical hemostasis of ingrown toenail and onychogryphosis.
- Cosmetic indications: Mole removal, telangiectasia, unwanted hair removal, scar revision, ear-lobe repair, development of flaps, oculoplastic procedures and blepharoplasties.
Precautions of this Procedure:
Radio Surgery should be avoided in unstable cardiac patients and in the treatment of the lesions of the skin overlying a pacemaker. Special care should be taken while performing radiosurgery near eye. Radio Surgery should not be done in presence of oxygen as there is risk of explosion. It should be made sure that patient is in contact with the ground plate during procedure. The operator should consider wearing a surgical mask and eye protection when working on lesions containing HPV.
Side Effects and Complications:
The common side effects that occur with radiofrequency are pain, tissue edema, bleeding, infection, post inflammatory hypo/hyper or depigmentation, scarring and keloid formation. The bacterial transference of Staphylococcus aureus through electrode from one patient to another is possible; however, it is much more possible during electrodessication than during electrocoagulation.