**4. Physical therapies for depigmentation**

Depigmentation with topicals is effective; however, they come with their share of side effects and can take up to 10 months or more for completion of the process and rarely complete depigmentation may not be achieved. Depigmentation by physical means, i.e., by cryotherapy and lasers, can be done when rapid depigmentation is desired or when patients have not responded well to topicals or have had contact dermatitis or any side effects due to the same.

#### **4.1 Cryotherapy**

Cryotherapy is nothing but cold therapy or the use of low temperatures to treat a variety of tissue lesions. With cryotherapy, it is possible to achieve rapid and permanent depigmentation via irreversible tissue damage resulting from intracellular ice formation. Liquid nitrogen is used as a cryogen for clinical use. The degree of damage depends on the rate of cooling and minimum temperature achieved. Further, inflammation develops within 24 hours of the treatment, which contributes to destruction of lesions via immunologically mediated mechanisms. In areas of koebnerization, cryotherapy is more effective.

#### *4.1.1 Procedure*

Initially, spot testing by a single freeze-thaw cycle is done. Once the edema and erythema subside, patches are treated with cryotherapy 3–6 weeks later. Either CO2 or liquid N2 can be used. A 2-cm flat-topped and round cryoprobe is used at approximately 40 mm from the skin surface. The whole patch is frozen with a single freeze-thaw cycle from the periphery followed by forming successive rows inward.

**61**

*Depigmentation Therapies in Vitiligo*

*4.1.2 Pros and cons*

**4.2 Laser therapy**

therapies [16].

• Fast and safe

*DOI: http://dx.doi.org/10.5772/intechopen.84271*

visible by the end of 4 weeks after the procedure.

• Low cost and simple to perform.

• Does not require anesthesia.

• Safe and efficacious.

Procedure should be terminated when a narrow (<1 mm) frost rim forms around the periphery of the cryoprobe. The rim can develop within 10–20 s by a cryogun

around the orbits or uneven areas of the nose, cryoprobes having smaller diameters may be required. No more than one freeze-thaw cycle is advised per session. There have been cases reported which have used two freeze-thaw cycles [18]. Results are

Alternatively, a cryospray/cryopen or the traditional dip-stick method of appli-

. For lesions

connected to a container with barometric pressure above 80 kg/cm2

cation can be used following the same freeze-thaw cycle protocol.

• Minimal wound care with no dressing or antibiotics.

• It can be performed only on smaller areas.

• Multiple sittings may be required.

dermatologist. A maximum of 80 cm2

• Selectively targets melanosomes and destroys

melanocytes and keratinocytes • Works better on tanned skin

• Duration of treatment is short • Larger areas can be treated effectively • Reduced risk of scar formation

• No scar formation if performed by an experienced dermatologist.

• If performed aggressively, it can lead to permanent scarring.

**Q-switched ruby Q-switched alexandrite**

Another faster method of depigmentation is the use of laser therapy. Lasers have been advocated more than MBEH and other bleaching agents due to their failure rate, as they have been proven to selectively destruct the melanocytes causing depigmentation. Further the risk of scar formation is minimized with laser

Mainly, the Q-switched ruby (QSR, 694 nm) and alexandrite (755 nm) lasers have been used in depigmentation. Both of these lasers operate in a similar manner in terms of mechanism of action. They induce photothermolysis of the pigmented lesions as they have wavelengths between 600 and 800 nm. These wavelengths are more readily and well absorbed by melanin. The frequency and pulse width is adjusted according to the skin type of the patient by a trained and experienced

area is treated per session.

pigmentation

with improved results

• Is efficacious in treating naturally occurring pigmented lesions as well as exogenous pigments • Safe, simple, and effective in treating recalcitrant

• Faster pulse frequency, hence rapid therapy • Higher wavelength so greater tissue penetration

#### *Depigmentation Therapies in Vitiligo DOI: http://dx.doi.org/10.5772/intechopen.84271*

Procedure should be terminated when a narrow (<1 mm) frost rim forms around the periphery of the cryoprobe. The rim can develop within 10–20 s by a cryogun connected to a container with barometric pressure above 80 kg/cm2 . For lesions around the orbits or uneven areas of the nose, cryoprobes having smaller diameters may be required. No more than one freeze-thaw cycle is advised per session. There have been cases reported which have used two freeze-thaw cycles [18]. Results are visible by the end of 4 weeks after the procedure.

Alternatively, a cryospray/cryopen or the traditional dip-stick method of application can be used following the same freeze-thaw cycle protocol.
