Monday, February 4, 2008

Permanent Hair Removal

Recently I posted on using hair for charity--raising money or making wigs. There are many of us who chose to remove unwanted body hair for cosmetic, social, cultural, or medical reasons. This includes both men and women. Even the indications that are considered "Medical indications" are influenced by the social and cultural norms. The hair on a chest like Tom Selleck's should be left alone (just my opinion), hairy backs are another thing.

The medical indications include:

  • Hirsutism, which is excess terminal hair in the distribution of hair growth influenced by androgens (ie, face, chest, back, abdomen)
  • Hypertrichosis, which is congenital or drug-induced increase in hair growth in areas that are not androgen dependent.
  • Pseudofolliculitis
  • Hair growth from a grafted donor site
  • Sex-change operations performed in men.

IMPORTANT TERMINOLGY

Temporary hair reduction is defined as a delay in hair growth, which usually lasts 1-3 months, consistent with the induction of telogen.

Permanent hair reduction refers to a significant reduction in the number of terminal hairs after a given treatment. This reduction must remain stable for a period of time longer than the complete growth cycle of hair follicles at the given body site. It has recently been suggested to add another 6 months to this posttreatment observation time (ie, the time necessary for a damaged follicle to recover from the laser injury and reenter a normal growth cycle). Note that "permanent" does not mean no regrowth of hair.

Complete hair loss refers to a lack of regrowing hairs (ie, a significant reduction in the number of regrowing hairs to zero). Complete hair loss may be either temporary or permanent.

METHODS of HAIR REMOVAL

There are many methods available for temporary or permanent hair removal. Each has its own relative efficacy and adverse effects. Different methods for the removal of body hair include the following:

  • Temporary hair removal - Shaving, epilation, depilation, bleaching

  • Temporary hair reduction - Eflornithine hydrochloride (VANIQA cream 13.9%), laser-assisted hair removal
  • Permanent hair removal - Electrolysis, Laser-assisted Hair Removal (LHR), Intense Pulsed Light Hair Removal (IPL)

Electrolysis

Electrolysis (or electrology) involves the insertion of a small, fine needle into the hair follicle, applying a pulse of electric current that damages and eventually destroys the hair follicle. Multiple treatment sessions are required to achieve a clinically significant result. The 2 types of electrolysis are galvanic electrolysis (direct current electrolysis) and thermolysis (alternating current electrolysis).

Proper electrolysis requires accurate needle insertion technique and appropriate intensities and duration of current. In addition, only anagen-phase hairs should be treated because telogen-phase hairs are believed to be more resistant to damage. Anagen-phase hairs can be distinguished easily from telogen-phase hairs by shaving the area to be treated and, in a few days, treating only those hairs visible on the skin surface (anagen-phase hairs).

Potential adverse effects of electrolysis include:

  • Scarring (ie, keloid formation)
  • Postinflammatory hyperpigmentation
  • Hypopigmentation
  • Pain--can be diminished with the use of topical anesthetic creams (Emla, ELA-Max, Topicaine) applied 1 hour prior to the procedure.
  • Local bacterial and viral infections

The adverse effects (and success) of electrolysis are dependent on technician experience and the duration and intensity of the current. Electrolysis is not safe for patients with pacemakers and should not be used on these patients.

Hair removal with light (laser, IPL)

Since 1996, when hair removal laser technology first became available for general use, numerous advances have occurred in laser hair removal. This has resulted in the many different types of lasers now available for treatment of excessive hair. Laser hair removal is based on the theory of selective photothermolysis, or selective destruction of the follicular unit, resulting in significant hair reduction in treated areas.

  • Selective photothermolysis --This principle predicts that selective thermal damage of a pigmented target structure will result when sufficient fluence at a wavelength, preferentially absorbed by the target, is delivered during a time equal to or less than the thermal relaxation time of the target. [When enough heat damage is done to the target --hair in this case]
  • Melanin is the natural chromophore (light-absorbing molecule)for targeting hair follicles. It's absorption spectrum is 250-1200 nm, which spans the entire ultraviolet, visible, and infrared light ranges.
  • When melanin absorbs energy in the form of heat from a pulse of laser light, there is "selective" heating which causes thermal injury to the melanin-containing cell (in this case, the hair follicle) and its surroundings. Ideally, the laser energy is absorbed selectively by the melanocytic hair bulb and matrix, thus destroying the hair follicle and its capacity to regrow, while protecting the surrounding tissue where the melanin concentration is minimal.
  • Melanin in the epidermis presents a competing site for absorption. In persons with darker skin, the higher levels of melanin in heavily pigmented skin (tanned, Asian, Blacks, etc) compete as a chromophore for the laser light. This light is converted to heat and can cause skin blistering or changes in skin pigmentation.
  • Selective cooling of the epidermis has been shown to minimize epidermal injury. Cooling can be achieved by various means, including ice, a cooled gel layer, a cooled glass chamber or sapphire window, a pulsed cryogen spray, or cooled airflow.
  • Laser treatment usually produces complete but temporary hair loss for 1-3 months, followed by partial but permanent hair loss. Multiple treatments may be necessary.

Before the widespread use of longer wavelengths and pulse durations and more effective cooling devices, laser-assisted hair removal was best used to treat individuals with light skin and dark hair. More recently, however, long-pulsed lasers have been used to safely and effectively treat patients with darker skin types.

Laser light sources currently used in hair removal treatments include:

Long-pulsed ruby

  • The long-pulsed ruby laser was the first widely used laser for hair removal. Its light energy has the most selective absorption by melanin and the shortest depth of penetration (wavelength of 694 nm).
  • Use of this laser for hair removal is indicated in individuals with light skin and dark hair.
  • Its efficacy has been demonstrated in numerous studies, ranging from 20-60% hair reduction after one treatment and up to 50-78% reduction after multiple treatments.
  • The ruby laser penetrates the skin by only 1-2 millimeters and can cause significant absorption by epidermal melanin of thermal energy. The use of this laser on patients with darker skin types is not recommended.

Long-pulsed alexandrite

  • The 755-nm alexandrite laser has now been widely used for laser hair removal. It is recognized as being efficacious and generally safe.
  • This laser is still typically used for patients with lighter skin types, but its longer wavelength allows for deeper penetration into the skin, and it can be used for patients with darker skin.
  • Studies have reported hair reduction from 4-56% after only a single treatment and from 33-95% hair reduction after multiple treatments, depending upon number of treatments and body location.
  • The adverse effects of this laser, when used on patients with darker skin types, can include blistering, crusting, and alterations of pigment, even when skin cooling devices are used. In patients classified as having the darkest skin, residual hypo- or hyperpigmentation is the rule with the alexandrite laser.

Long-pulsed diode

  • The 810-nm long-pulsed diode laser has been demonstrated to have hair removal capacity comparable to those of the ruby or alexandrite lasers. After a single treatment, hair reductions of 32-34% have been reported, and up to 84% hair reduction has been reported after multiple treatments.
  • The diode laser can be used in darker skin types because of its longer wavelength and adjustable pulse duration. It should be used with an efficient skin-cooling device.
  • Still, temporary adverse effects have been reported with the use of the diode laser in the form of postinflammatory hyperpigmentation when used on individuals with dark skin.

Long-pulsed Nd:YAG

  • The Nd:YAG laser is the safest type used to treat unwanted hair on patients with dark skin and is most suitable for patients in this group. At 1064 nm, this laser penetrates the skin deeper than other lasers (to a level of 4-6 mm) with less absorption at the skin.
  • It is also less effectively absorbed by melanin. This leads to lower instances of adverse effects and better tolerance in patients with dark skin, but also lower efficacy for hair removal.
  • Permanent hair loss has been reported, however, with reported hair reductions of 27-53%, depending on the number of treatments administered and the body location.
  • The FDA has approved the long-pulsed diode and the long-pulsed Nd:YAG lasers for use in hair removal in patients with darker skin classifications. All FDA-approved laser systems used for hair removal must have efficient and effective epidermal cooling devices incorporated as part of the system.

Intense pulsed light systems

  • Intense pulsed light (IPL) systems utilize a xenon bulb as a light source, which produces polychromatic light with wavelengths from 550-1200 nm. This is in contrast to laser light sources, which produce monochromatic light of a specific wavelength. Light emitted by the bulb passes through a filter that excludes shorter wavelengths that may severely damage skin.
  • The ability to "tune" the wavelength of light emitted by these systems gives IPL systems the advantage of versatility. Using different filters, a pulsed light system could mimic any number of laser systems, allowing the operator to treat many different conditions amenable to light therapy, including, of course, the removal of unwanted hair.
  • Studies have shown intense pulsed light to be an effective method of hair removal. In a study of 210 patients who underwent hair removal by IPL, a mean hair reduction of 80% was reported after 3-5 treatments.
  • Minimal adverse effects, including transient erythema and localized edema, were reported.

Skin Prep and Safety

  • Patients should be instructed to avoid sunlight and active tanning prior to treatment.
  • Patients may shave or use depilatory creams up to the day prior to treatment. Tweezing should not be done, as the hair follicle/shaft is needed for the treatment to work.
  • Topical anesthetic creams may be applied to the treatment area to reduce discomfort during the procedure. Cold compresses are also effective in reducing discomfort, erythema, and edema at the treatment area.
  • The skin surface must be thoroughly cleansed of all makeup, anesthetic creams, and other applicants immediately prior to laser treatment. This may be done with water, followed by alcohol swabs, and should be allowed to dry completely.
  • Laser systems are dangerous hazards to the eye. The highest concentration of melanin in the body is contained in the retina, which is highly susceptible to damage by laser light. Every person in the room during laser treatment should wear protective eyewear that is certified for the wavelength of the laser in use. Because the patient usually lies supine, he or she may require full occlusive eye protection to prevent laser light from entering underneath a sunglasses or goggle type of protective eyewear.
  • A higher occurrence of adverse effects and adverse reactions has been noted at the neck region in women; higher fluences in this area should be used with caution.
  • For treatment of the chin, perioral region, or upper lip, tooth enamel should be protected from excessive laser light exposure. Inappropriate exposure to certain laser light may induce hard tissue disintegration in the tooth and irreversible damage to dental pulp.
  • During laser treatment, each laser spot should overlap by no more than one third of the spot size. Further overlapping of continuous pulses causes accumulation of thermal injury and potentially causes epidermal damage. No overlapping of spots could result in missed areas in the treatment area.

Post-procedure Care:

  • Cold compress or ice pack may be used to decrease pain and reduce swelling.
  • Patients may also be given a topical corticosteroid cream to decrease local erythema.
  • If minor skin damage has occurred, a topical antibiotic ointment may be applied until the skin has sufficiently healed.
  • For more serious skin damage, an oral antibiotic may be prescribed for prophylaxis if deemed necessary by the health care provider.
  • Makeup may be applied to treated areas the day following the procedure if no epidermal damage has occurred.
  • Patients should be told that hair casts will shed from treated areas over the following week and that this should not be confused with new hair growth.

Future treatments should be planned when they are likely to be most effective. Timing depends upon the body surface area to be treated.

  • Hair on the trunk and extremities grows more slowly than on the face and head, and future treatments to the trunk and extremity should be planned after 2-4 months.
  • In women, facial hair is lighter in color and finer in texture than on other parts of the body. These hair properties make the face a resistant area to treatment. Therefore, greater numbers of treatments are often required, and at shorter intervals. Treatments of the face should be timed at intervals of approximately 4-6 weeks.

Complications:

Immediate effects after a single treatment of laser-assisted hair removal include perifollicular erythema and edema. These are expected after treatment and should not be considered adverse effects. They are minimized by cold application and resolve in a few hours.

The risk of developing adverse effects or complications after laser-assisted hair removal varies widely and depends upon many factors including the type of laser used, skin color, etc.

  • Blistering -- is a result of injury to the epidermis, possibly due to high fluences or increased overlapping of laser pulses. It is the most common complication and can occurs with all lasers/IPL.
  • Scab formation is another common adverse effect of laser treatment. Blistering and minimal epidermal crusting have been reported in up to 15% of patients treated with both ruby and alexandrite lasers. These occurrences are more common in patients with tanned skin and darker skin types.
  • Hyperpigmentation is a darkening of the skin and can occur after laser treatment. This phenomenon is usually reversible and is due to a stimulation of melanin production in skin melanocytes. This reaction is similar to a suntan.
  • Hypopigmentation, or lightening of the skin, can occur after laser treatments. This is caused by damage to the epidermal melanocytes after their melanin absorbs laser light energy, causing destruction of these cells. This type of damage may be permanent and occurs more commonly in patients with darker skin.

JUST FOR FUN! Hairy Back Spoof

REFERENCES

Nonlaser Hair Removal Techniques; Alicia Barba MD, Leslie S Baumann MD, and Esperanza C Welsh; eMedicine Article, December 15, 2004

Electrolysis - DermNet NZ

Laser-Assisted Hair Removal; Christine Dierickx MD; eMedicine Article, April 12, 2006

Laser Hair Removal; Joseph A Molnar MD, Christian N Kirman MD, and Samer Alaiti MD; eMedicine Article, February 21, 2007

On the Physics of Laser-induced Selective Photothermolysis of Hair Follicles: Influence of Wavelength, Pulse Duration, and Epidermal Cooling; Journal of Biomedical Optics, Vol 9, No 2, pp 353-361; Lars O Svaasand, J Stuart Nelson

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