Hair removal with the 3-msec alexandrite laser in patients with skin types IV-VI: efficacy, safety, and the role of topical corticosteroids in preventing side effects

Journal of Drugs in Dermatology, Jan, 2007 by Mohammed S. Aldraibi, Dany J. Touma, Amor Khachemoune

Abstract

Background: Laser hair removal targets melanin in the hair shaft. The abundance of melanin in the epidermis of patients with dark skin color has always been regarded as hazardous due to the increased incidence of side effects in this patient population.

Objective: To establish the efficacy and safety of using the 3-msec alexandrite laser in patients with skin types IV to VI, and evaluate the role of topical corticosteroids in preventing side effects.

Methods: Thirty-seven patients with skin types IV to VI and brown or black hair were recruited and divided into 2 groups. Twenty-six patients were treated with the 18-mm spot size and 11 patients were treated with the 15-mm spot size. Hair shafts in the treatment and control areas were counted and clipped for measurement of the thickness at the base. The laser was used with fluences between 8 and 32 J/[cm.sup.2]. Two 16-[cm.sup.2] areas were treated; one area was pretreated with a class I topical corticosteroid (TCS) cream (betamethasone dipropionate) 10 minutes prelaser and twice a day for 5 days postlaser. The dynamic cooling device (DCD) spray duration was set at 90 msec, and the delay was set at 20 msec. Pain was graded on a scale from 1 to 10. Patients were followed up on day 1 and day 7 and at 1, 3, and 6 months. Histological samples from the 2 treatment areas and control were obtained from 5 patients. At follow-up visits, side effects were graded on a scale from 1 to 3. Hair reduction was evaluated by performing hair counts. The thickness of hair was measured microscopically at the base. Average hair count reduction and hair thickness were recorded at the 3- and 6-month visits.

Results: Thirty-one patients completed the study. The average hair count reduction at 6 months was 35.4%. The average hair thickness reduction was 31.2%. At one week hyperpigmentation was seen in 48.4% of the laser only treated area and in 45.2% of laser/TCS treated area. The effect of TCS was minimal and more prominent at 1 and 3 months. The incidence of hyperpigmentation was higher in the 15-mm group than the 18-mm group as a result of using higher fluence. Hypopigmentation was generally preceded by crust formation and lasted up to 3 months. Reducing spot size resulted in decreased peripheral crust formation. TCS appears to have a role in reducing the erythema and crusting. Histopathology of both groups at day one showed necrosis of the follicular infundibulum and the inner layer of the perifollicular epithelium. No vascular damage was seen.

Conclusion: The 3-msec alexandrite laser utilized in this study provides a safe and effective treatment achieving long-term reduction of unwanted, pigmented hair in skin types IV and V, but is less safe in skin type VI. Using a TCS helps in minimizing post-treatment erythema and edema; it also decreases the duration of hyperpigmentation.

Introduction

Laser hair removal is based the principle of selective photothermolysis. Hair is the only pigmented (melanized) structure normally present in the dermis. The absorption of the laser light by melanin transforms the energy into heat. Heating the follicular epithelium, including the papilla and bulge to approximately 200[degrees]C destroys or damages these structures pivotal to hair growth. (1,2) To permanently damage the hair follicle, it is necessary to damage the stem cells located in the bulge area. (3)

A marked decrease in hair growth is a reasonable expected response following laser irradiation. (4,5) To date, there is no single laser hair removal system that can remove hair of all colors, including gray or white, on all skin types. (6) In darker skin, laser hair removal can be used effectively, although the potential of side effects is greater unless longer wave-lengths are used. (7)

Several alexandrite lasers produce laser light of 755 nm. The 755-nm wavelength is not as well absorbed by epidermal melanin than the 694-nm wavelength of the ruby laser and, thus, may be less damaging to skin in patients with skin types V to VI. (7,8) Relatively long pulse durations enhance thermal destruction of the hair follicle. (2,9) Several studies using the alexandrite laser with significant hair reduction and variable incidences of side effects have already been published. (10-13)

Topical corticosteroids have been used in laser treatment to reduce posttreatment complications by limiting erythema and decreasing inflammation. The ability of a given glucocorticoid agent to cause vasoconstriction usually correlates with its antiinflammatory potency. (14) Penetration of the glucocorticoid cream varies according to the skin site (ie, 4 times greater in the eyelids and scrotum than the forehead, and 36 times greater than the palms and soles). (14-16) It is known that glucocorticoids inhibit phospholipase A2 in cells by directly inducing phosphorylation of the enzyme, which causes liberation of arachidonic acid from cell membranes, thus inhibiting the arachidonic acid pathway. (14) Other proposed mechanisms for the antiinflammatory effects of glucocorticoids include inhibition of phagocytosis and stabilization of lysosomal membranes of phagocytic cells. (14,17)