LASERS AND THEIR TREATMENT
LASER is an acronym for Light Amplification by Stimulated Emission of Radiation, and the underlying principle of laser action was first described by Albert Einstein in 1917. A laser is a device that generates an intense beam of light. Light is a part of the spectrum of electromagnetic energy. The emissions that make up this spectrum travel at the speed of light. Under certain conditions, light exhibits the characteristics of a wave, and the wave length determines the functional properties of laser energy. Medical lasers are generally based on wavelengths in the infrared, visible and ultraviolet portion of the spectrum.
In the early 1960's the only medical lasers available were those having wavelengths in the visible electromagnetic spectrum. So treatment was generally limited to pigmented lesions. But continued research and comprehension of the significance of wavelength, power density, beam quality, and pulse format, and their effect on tissue cutting, vaporizing, and coagulating have resulted in an explosion of medical laser technology.
There are several types of lasers commonly used in medicine. Based on their specific parameters, some are better suited for certain applications than others. The most frequently used lasers in medicine are the carbon dioxide (CO2 ), erbium:yttrium-aluminum-garnet (Er:YAG), homium: YAG (Ho:YAG), neodymium:YAG(Nd:YAG), double neodymium:YAG (KTP), argon ion, krypton ion, helium neon (HeNe), visible dye, and excimer. And within these types of lasers, there are scores of "brands" of lasers.
Lasers have been used in plastic surgery for 40 years, mostly for the treatment of vascular or pigmented skin lesions - those in the visible wavelength. Since the development of high energy pulsed laser systems in the mid 1990's, laser skin resurfacing has truly emerged as the premier mode of treatment for skin "recontouring" (improvement of roughened surface texture), correction of severely sun-damaged skin including sun-induced wrinkles and pigmentation changes, and improvement of scars.
Vascular Lesions
Vascular skin lesions are categorized according to pathology and age of onset. Congenital lesions begin in infancy and include port-wine stains, hemangiomas, venous malformations, and lymphangiomas. Congenital lesions are found most commonly on the head or neck and may be isolated or found as part of a congenital syndrome. Acquired lesions develop in persons of any age and include telangiectasias, cherry angiomas, pyogenic granulomas, venous lakes and poikiloderma. Acquired lesions may occur spontaneously, or they may be caused by trauma, ultraviolet exposure, or hormonal changes.
The pulsed dye laser has been used successfully to treat a variety of vascular lesions due to its ability to destroy the target of vascular structures, oxyhemoglobin. These lesions include superficial vascular malformations (port-wine stains), facial telangiectasias, hemangiomas, pyogenic granulomas and poikiloderma. Vascular malformations associated with smaller more superficial blood vessels respond better to treatment than deeper larger vessels. Multiple treatments at approximately monthly intervals are often required for better results. Further treatments may be necessary if the vascular lesion recurs. Because pulsed dye laser efficacy is limited by the depth of vascular injury, deeper vascular lesions may be better treated with a more aggressive light source system.
Pigmented Lesions/Tattoos
Pigmented lesions have been associated with beauty as well as disease. "Beauty marks" may be the signature of those who have a unique facial birthmark, but others may seek to remove unsightly moles or pigmented skin lesions. Sun exposure may also produce pigmentation changes that may be either cosmetically undesirable or are pathologically of concern.
As a physician who treats many skin problems, it is Dr. Rasmussen's role to determine which pigmented skin lesions warrant biopsy with histologic evaluation as opposed to those lesions that are candidates for cosmetic removal - either by shaving, definitive excision, or laser treatment. With the advent of pigment-specific lasers, selective treatment of many pigmented skin lesions is possible, leaving the non pigmented portion relatively undisturbed and making an excellent outcome probable. Among pigmented lesions amenable to laser treatment are solar lentigenes ("sunspots"), cafe-au-lait spots, freckles, post inflammatory hyperpigmentation, melasma, and a variety of benign nevi ("moles").
Some pigmented skin lesions should not be treated by laser. These include melanoma, lesions that could be confused with melanoma (such as dysplastic nevi), and lesions that have the potential to develop into melanoma (such as lentigo maligna and certain nevi). Biopsy should be performed prior to laser treatment of any uncertain pigmented skin lesion because ablative therapy carries the risk of disguising it.
The range of effects of laser on a pigmented lesion depends on the amount of pigment in the lesion, the depth the pigment is located within the skin, and skin type and condition. Laser factors that effect successful treatment include wavelength, energy and exposure time. The goal is to select the laser which delivers sufficient amount of energy of the proper wavelength and pulse durations to destroy a target with limited damage to surrounding normal tissue. Commonly used lasers include the pulsed dye pigment laser, tunable pulsed dye laser, Q-switched ruby, Nd:YAG, and Q-switched alexandrite laser. Like the vascular laser, multiple treatments are frequently necessary for best results.
Of note, the same principles noted above for pigmented skin lesions apply to the removal of pigmented tattoos. However, there are several other factors which effect results. These are based on whether the tattoo was placed professionally, since this affects depth of pigment (professional tattoos are usually deeper in the skin and more refractory to treatment), type of pigment used (professional tattoos usually contain many different dyes, occasionally mixed with metallic elements, and pigments with iron or titanium oxides can undergo immediate pigment darkening), color (professional tattoos often have a variety of colors, and the best wavelength must be selected to treat the individual tattoo pigment), and complexity (professional tattoos may result in textural changes of the skin, even scarring, that may not be evident on casual inspection). Therefore, while amateur tattoos can usually be removed completely in a few treatments with superior cosmetic results, laser treatment of professional tattoos may result in hyperpigmentation, hypopigmentation, areas of faint ink persistence, and mild textural skin changes. The goal of laser treatment of the complex multicolored tattoo is to provide the patient with a result that is unrecognizable as a tattoo on casual inspection.
Laser Skin Resurfacing
To understand the mechanism behind laser skin resurfacing for rejuvenation of photo-aged skin, it is helpful to understand how chronic sun exposure alters normal components of skin.
Collagen is the main structural extracellular matrix component of skin. Elastic fibers, while composing a relatively small portion of skin (1-2 %), are critical to the ability of skin to stretch and recoil. Glycosaminolglycans, proteoglycans and fibronectin are widely distributed in skin, and while they compose only a small percentage of dry weight of skin, they bind a large amount of water and thus regulate skin hydration which in turn affects cellular mobility. Proteoglycans and fibronecin also play a role in cell migration necessary for skin remodeling or wound healing.
Aging of the skin occurs as a result of 2 distinct processes - chronologic aging is related to our "biologic clock" and continues with less influence from outside agents. Chronologically aged skin demonstrates thinning of the dermis and decrease cellularity, including loss of elastic fibers and collagen. This results in loss of resiliency and a slower healing response. Photo-aging however, is a direct result of continued exposure to UV rays and our ability to fight this damage with melanin pigment synthesis and antioxidant capabilities of our skin. In contrast to the more subtle changes from chronologic aging, the changes from chronic sun exposure can be quite pronounced. The normal fine meshwork of elastic fibers superimposed on a background of dense, well-organized collagen fibers is replaced with a massive accumulation of elastic fibers in an abnormal and haphazard arrangement against a backdrop of poorly organized collagen strands. In contrast to the large increase in abnormal elastic tissue is the decrease in collagen fibers.
To achieve an improvement in photo-aged skin, the skin must be injured in order to promote dermal wound healing and regeneration. To simplify a complex process, after tissue injury occurs, repair takes place in a series of interrelated steps including cell migration and collagen production and deposition forming the final matrix in the evolving scar. The collagen network matures, contracts and strengthens over months; normal elastic fibers may or may not appear or reform only partially in a mature healed wound.
What this means is that to achieve more dramatic improvements in photo-damaged skin, modalities that destroy the surface of the skin will promote more "wound healing" with skin regeneration. The deeper one treats the skin, the more dramatic the result, the longer lasting the result, but with longer healing time, and greater sequelle and potential risks. Dr. Rasmussen offers 2 levels of laser skin resurfacing - FRAXELTM and the CO2 laser.
The CO2 laser is the most effective tool for improving sun-induced wrinkles and pigmentation changes and smokers-damaged skin. After healing, the facial skin looks like a "baby's butt". But there is significant downtime and it will result in a persistent pink tinge to the skin, often lasting several months. It will also result in a lightening of the skin resulting in a line of demarcation below the jaw line. This limits treatment to the face.
The FRAXELTM laser results in only 2 to 4 days of social downtime, but requires several ( 3 - 5 ) sessions to attain the best results. Unlike the CO2 laser, it will not result in "baby's butt" skin, but the results can be very satisfying without the sequelle and potential risks. Plastic surgeons like Dr. Rasmussen who perform FRAXELTM usually report that it attains approximately 75% of the CO2 laser results. Another significant advantage is that it can be used on body sites other than the face, such as the neck, décolleté and hands.
Hair Removal
Hair serves various functions in humans, including thermoregulation, photo protection, and dry lubrication. But unwanted pigmented hair is a common cosmetic problem for both men and women. Until recently, the only long-lasting method of hair removal was electrolysis which permanently damages 15-20% of hair follicles but with a small risk of scarring (especially "follicular bumps"). Laser hair removal has emerged over the last several years as a viable alternative. To understand hair loss, it is first helpful to understand hair growth.
All hairs undergo a cycle of active growth, transition, and resting phases. Understandably, laser treatment is most effective when the hair is in the active growth phase. Different body sites have different amounts of duration in the active growth phase. And even all hairs in a given region are not in the active phase at any given time. Therefore, hair removal sessions must be repeated to "capture" hairs during the active growth phase. As an example, the resting phase on the leg may be as long as a year. So treatments should be "timed" so that the largest numbers of hairs are in the active growth phase based on the body location; put another way, several treatment cycles are required with the spacing between treatments dependent on the body area being treated. This can range from 4 to 6 sessions.
Laser best treats dark hair on fair skin. Complications are rare such as superficial burns and scarring, but pigmentation changes are more likely in less fair skin. Increased growth of fine dark hair in untreated areas in close proximity to treated areas have been reported.
Laser treatment usually produces complete but temporary hair loss for 1-3 months, followed by partial but permanent hair loss. Permanent hair removal is defined as significant and stable loss of hair for a period longer than the complete natural hair growth cycle. The FDA defines "permanent hair loss" as loss of hair for at least 6 months. With the evolution of long-term hair removal, lasers have become smaller, faster, and more effective, and Dr. Rasmussen is pleased to offer for purchase Silk'nTM a personal hair removal system with Home Pulsed LightTM. Silk'nTM was featured on Good Morning America and received rave reviews. The cost of Silk'nTM is less than the cost of a single treatment area by laser hair removal centers.
