19 Aesthetic Principles and Consultation

Minimally invasive aesthetic procedures have become the treatments of choice for rejuvenation of aging skin and facial enhancement.¹ Since approval of botulinum toxin, dermal fillers, and lasers by the Food and Drug Administration (FDA) for cosmetic use, there has been a shift away from more traditional invasive surgical procedures that may radically alter appearance toward procedures that can enhance appearance in more natural and subtle ways. According to statistics from the American Society for Aesthetic Plastic Surgery, over 10 million aesthetic procedures are performed in the United States and more than 80% are minimally invasive.² The most commonly performed procedures include onabotulinumtoxinA (Botox; formerly known as botulinum toxin type A) and dermal filler injections for treatment of wrinkles; lasers and intense pulsed light technologies for hair reduction, skin resurfacing, and photorejuvenation; and chemical peels and microdermabrasion for exfoliation.

These aesthetic procedures are associated with high patient and provider satisfaction because they are efficacious, have low risks of side effects, involve minimal patient discomfort with short recovery times, and can be safely performed in the office setting.^3,⁴ As the popularity and demand for minimally invasive aesthetic procedures continues to grow, more health care providers are choosing to incorporate these types of treatments into their practice. This introduction to the aesthetic section of the book presents basic aesthetic principles for providers who wish to get started with aesthetic medicine. The succeeding chapters demonstrate the most commonly performed aesthetic procedures that can be readily incorporated into office practice.

Facial Aging

Facial aging is associated with a gradual thinning of the skin and loss of elasticity over time accompanied by the diminishment of dermal collagen, hyaluronic acid, and elastin. Ultraviolet (UV) radiation from sun exposure accelerates this process at a higher rate than does chronologic aging. This UV aging process is termed photoaging. To appreciate the contribution of photoaging to the appearance of aged skin, one needs only compare photoprotected skin, such as skin on the inside of the upper forearm or under the chin, to the appearance and texture of skin on face and back of the hands. Photoaged skin typically exhibits the following changes (Figure 19-1 for a computer-enhanced image demonstrating these signs)⁵:

FIGURE 19-1 Photoaging changes (computer-enhanced image).

(Copyright Rebecca Small, MD.)

• Textural changes

• Wrinkles (also called rhytids)

• Dry and rough skin

• Dyschromia

• Solar lentigines

• Mottled pigmentation

• Postinflammatory hyperpigmentation

• Degenerative changes

• Benign

• Preneoplastic and neoplastic.

In a study by New York plastic surgeon Dr. D. Antell on aging in identical twins, extrinsic factors, such as prolonged sun exposure, resulted in advanced aging changes (Figure 19-2A) relative to the intrinsic aging seen in non–sun-exposed twins (Figure 19-2B).⁶ Habitual facial expressions also contribute to formation of visible lines and wrinkles, particularly in the upper one-third of the face, because repetitive muscle contractions etch in frown lines between eyebrows and crow’s feet radiating from the corner of the eyes. In addition to skin laxity, volume loss, and dynamic musculature, facial aging also results from biometric facial changes such as descent of malar fat pads, which contributes to deepened nasolabial folds, and resorption of maxillary and mandibular bone, which contributes to radial lip lines and mental crease formation.^7,⁸

FIGURE 19-2 Facial aging differences in identical twins. Advanced photoaging changes of (A) skin wrinkling and laxity with prolonged sun exposure and (B) mild changes with minimal sun exposure.

(Courtesy of Dr. D. Antell, New York City, www.Antell-md.com.)

Skin Anatomy

The skin is divided into three layers: the epidermis, dermis, and hypodermis or subcutaneous layer (Figure 19-3). The epidermis is the top layer of the skin and is composed of four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. The epidermis is further divided into the outermost nonliving layer, the stratum corneum, and the living cellular layers of the stratum granulosum, stratum spinosum, and stratum basale.

FIGURE 19-3 Skin anatomy.

(Modified from White CR, Bigby M, Sangueza OP. What is normal skin? In: Arndt KA, LeBoit PE, Robinson JK, Wintroub BU, eds., Cutaneous Medicine and Surgery. Philadelphia: Saunders; 1996:3–41.)

The stratum corneum is composed of corneocytes and lipids, which serves as a barrier against microbial pathogens and environmental irritants and also keeps the skin hydrated and protected from injury. Constant renewal is necessary for the epidermis to maintain its integrity and function effectively. In healthy young skin, it takes approximately 1 month for keratinocytes to migrate from the living basal layer of the epidermis to the stratum corneum surface and desquamate, during the process of epidermal renewal. Figure 19-4 shows the structure of the epidermis with the keratinocyte maturation highlighted. Photoaged skin demonstrates slower keratinocyte maturation and abnormal retention of cells in the epidermis. This results in a rough and thickened stratum corneum with impaired barrier function, reduced hydration capabilities, and increased pigmentation from retention of melanin-laden keratinocytes in the epidermis.