Cosmetic Dermatology

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Cosmetic Dermatology

As our population ages, its desire for cosmetic dermatology increases. For the aim of cosmetic dermatology is not to alleviate disease, but to try to make the skin look young again. Perhaps the desire to look young and beautiful seems frivolous, but success has measurable benefits. Studies consistently show that good-looking men and women earn more, are more successful at interviews and have a higher sense of self-worth. In contrast, well-constructed trials and impartial data on the results of cosmetic dermatological procedures are scanty.

In the United Kingdom, with its relatively few dermatologists, hardly any deal only with cosmetic skin problems, but in the United States the proportion is much higher. Dermatologists have been at the forefront of cosmetic procedures. They have made numerous contributions in this field, including the introduction of tumescent anaesthesia, laser physics, hair transplantation and the use of fillers and botulinum toxins. Thus, all dermatologists should know which cosmetic procedures can be performed, and their risks and benefits. This chapter gives an overview of the most common techniques in current use.

Ageing of the skin

Ageing of skin is a mixture of environmental influences and chronological ageing. Exposure to extrinsic factors such as ultraviolet radiation, smoking, poor nutrition and exposure to chemicals result in skin that is more deeply wrinkled, with reduced elasticity, and an epidermis showing solar lentigines, telangiectasia, enlarged pilosebaceous units and keratoses, and scattered pigmentation (see also p. 212). Photoaged skin has reduced levels of the fibrillar collagens, a major structural element in healthy dermis, and a disrupted elastic fibre network. The loss of collagen correlates with the depth and number of wrinkles, and is the result of a combination of reduced procollagen synthesis and increased breakdown by matrix metalloproteinase (MMP) enzymes. Ultraviolet radiation generates free radicals in the dermis and epidermis that alter protein structure directly, as well as initiating signal transduction cascades that activate MMPs. Histologically, the epidermis is thinned, with reduced proliferation and a flattened rete ridge pattern. The Glogau scoring system can be used as a clinical indicator of degree of photoageing (Table 22.1).

Table 22.1 Glogau photoageing grade.

Grade	Skin findings
I	No wrinkles Mild pigmentary changes No keratoses
II	Wrinkles in motion Early senile lentigines Palpable but invisible keratoses
III	Wrinkles at rest Dyschromia and telangiectases Visible keratoses
IV	Yellow–grey skin colour Prior skin malignancies Wrinkled throughout

Chronological ageing, on the other hand, is largely due to genetics. Intrinsic factors including redistribution of subcutaneous fat, bone remodelling and repeated facial muscular activity contribute to the ageing appearance of the face. The loss of subcutaneous fat in the forehead, temples, malar cheeks and peri-oral area and descent of fat along the jowl and peri-orbital area result in a sagging, sunken appearance. Bone resorption in the inferior orbital rim and mandible further exaggerates the volume loss to the lower face. Finally, repeated muscular contracture around the peri-orbital area give rise to dynamic and static glabellar lines and crow’s feet.

In medical dermatology, several different treatments may be needed over time to treat, for example, a psoriatic patient. Similarly in cosmetic dermatology no one technique can reverse all the changes of photoageing, and treatments must be tailored to the individual. The techniques used most commonly are the application of emollients and retinoid creams, facial peels, injection of botulinum toxin and dermal fillers, and laser and light sources. As a general rule, the choice of treatment depends on the depth of the pathological changes. Superficial changes, such as pigmentary ones and early keratoses (Glogau I and II), are best treated with agents acting on the epidermis, such as topical retinoids and shallow facial peels. In contrast, wrinkles caused by dermal changes and underlying volume loss need treatment that reaches the deeper layers of the skin – such as ablative laser therapy or the injection of fillers.

Cosmeceuticals

The over-the-counter cosmetics industry is worth $160 billion per year worldwide, and in America more is spent on beauty products than on education. However, the definition of what is a cosmetic, as opposed to a medicine, is still confusing. The term ‘cosmeceuticals’ further confuses consumers, as these topically applied products claim to be a blend of cosmetics and pharmaceuticals, with claims to reduce wrinkles and improve skin tone and texture. In 1938, the American Food and Drug Administration (FDA) defined a cosmetic as anything that can be ‘poured, sprinkled or sprayed on, introduced into, or otherwise applied to the human body…for cleansing, beautifying, promoting attractiveness, or altering the appearance without affecting the body’s structure or functions’. This has led to confusion in which the cosmetic industry wants to claim rejuvenating properties for its products, but not such dramatic ones that they become classified as medicines, and so are available only with a medical prescription and subject to the review by the FDA. This discourages the open publication of research carried out by the industry, as the absence of effect of their products will not help sales, and the finding of true alterations in the structure of the skin carries the risk having the product classified as a medicine. European regulations are less conservative, and state ‘almost every product usually perceived as a cosmetic…does, in some way or another, modify physiological function…the modification has to be more than significant’ for the Medicinal Product Directive to apply.

Emollients (p. 397)

Even mildly aged skin looks better after the application of moisturizers. The scaliness of aged skin is due to corneocytes (p. 10) clumping together into lamellae, instead of being shed separately. Emollients help to ‘unstick’ the corneocytes, and contain two main types of ingredient: occlusives and humectants. Over-the-counter preparations are usually mixtures of these, prepared either as oil-in-water emulsions (creams and lotions) or water-in-oil emulsions (hand creams). Occlusives (such as soft white paraffin or lanolin) are poorly permeable to water, and so reduce trans-epidermal water loss when applied to the skin. Humectants absorb water, generally from the environment, but also from the epidermis. They draw water into the stratum corneum, and the resulting swelling of corneocytes gives an impression of wrinkle reduction, although this is only temporary. Over-the-counter moisturizers advertised as ‘anti-wrinkle creams’ usually rely on this mechanism. Urea, glycerine and hydroxy acids are all humectants.

Retinoids (p. 405)

Trial data confirm that topical tretinoin improves the appearance of mild to moderate photodamage. Fine and coarse wrinkles, pigmentary changes and keratoses improve as new collagen is formed in the dermis. Skin irritation is common, and both this and the improvement in appearance correlate with the concentration of tretinoin used.

Botulinum toxin

Clostridium botulinum was identified at the end of the nineteenth century as the organism responsible for the potentially fatal disease botulism, in which paralysis of the cranial and autonomic nerves follows the ingestion of its toxin. There are seven serotypes of botulinum toxin, of which A, B and E account for the majority of human disease. The toxins work at the neuromuscular junction, where they produce a chemical denervation by binding irreversibly at the presynaptic junction and blocking the release of acetylcholine. Despite the permanent binding of the toxin, paralysis wears off after several months as collateral axonal sprouts develop, able to release acetylcholine.

Botulinum toxin was first used clinically in the 1980s to correct squints and cervical dystonia, but moved rapidly into cosmetic use when it was found to be effective at reducing wrinkles. Its use is one of the most popular cosmetic procedures because it is easy to administer and starts to work after only a few days.

Types of botulinum toxin

Four types of botulinum toxin are available in the United Kingdom (Table 22.2). Vistabel® (Botox cosmetic® in the United States) is a type A botulinum toxin, licensed to treat glabellar lines, for which it should now be used in place of the identical Botox®. Azzalure® (identical to Dysport®) and Bocouture (identical to Xeomin) are also type A botulinum toxins, while Neurobloc® is a type B toxin. All three type A botulinum toxins contain the same type A toxin molecule consisting of a light chain that promotes its translocation into the presynaptic terminal and a heavy chain that cleaves SNAP-25 (synaptosome-associated protein), inhibiting the release of acetylcholine. They differ in the amount and size of the complexing proteins. Clinical data show similar efficacy and duration of action. All except for Neurobloc are licensed for cosmetic use to treat glabellar frown lines. Type A botulinum toxins do not take effect for several days after injection, and their actions last for 3–4 months. With repeated injections, patients often note the aesthetic improvements last longer than 6 months. Neurobloc® (Myobloc in the United States) has a shorter action of around 6 weeks. Neurobloc is not licensed for cosmetic use and this must be explained to patients. Clinical studies have suggested that Bocouture is bioequivalent to Vistabel or Botox (1 unit Bocouture = 1 unit Botox). The potency of Azzalure is calculated differently, with 1 unit of Botox/Vistabel® being roughly equivalent to 2.5 units of Azzalure®.

Table 22.2 Botulinum toxins available in the United Kingdom.

Toxin type	Trade name	Drug name	Manufacturer	UK license for cosmetic use?
Type A	Vistabel (Botox cosmetic)	OnabotulinumtoxinA	Allergan	Yes, 2006
	Azzalure (Dysport)	AbobotulinumtoxinA	Galderma/ Ipsen	Yes, 2009
	Bocouture (Xeomin)	IncobotulinumtoxinA	Merz	Yes, 2010
Type B	Neurobloc (Myobloc)	RimabotulinumtoxinB	Eisai	No

Uses of botulinum toxin

Botulinum toxin is primarily used to treat ‘dynamic wrinkles’ (i.e. wrinkles produced by muscle contraction). The upper part of the face is most amenable to treatment, as wrinkles here are caused by the contraction of specific muscles, such as the frontalis (leading to horizontal wrinkles on the forehead), procerus and corrugator (causing vertical glabellar frown lines) and lateral orbicularis oculi (resulting in crow’s feet). While botulinum toxin is only indicated for glabellar lines, experienced physicians have also found other off-labelled uses in treatment of wrinkles of the upper lip, marionette lines, bunny lines from nasal scrunching, mental creases and platysmal bands. These areas should be approached with caution, however, as poor technique may result in difficulty with facial expression and physiological function.

A glabellar frown typically needs injection into each corrugator and the procerus muscle. Five injection sites in a V distribution is often used to eliminate the vertical and horizontal rhytides in the glabellar complex. To avoid lid and brow ptosis, the most lateral injection should be placed slightly medial to the mid-pupillary line and 1 cm superior to the orbital rim. To treat horizontal wrinkles on the forehead, botulinum toxin is injected roughly every 2 cm along the frontalis muscle (Figure 22.1). A more feminine arched brow appearance can be created by raising the lateral injection sites slightly to allow some function of expression in the lateral brow. In men, a horizontal pattern is used to prevent the cockeyed appearance. ‘Crow’s feet’ (peri-ocular rhytides) are treated with injections 1 cm lateral to the lateral canthus.

images — **Figure 22.1** Before (a) and after (b) photographs of the effect of botulinum toxin injections on glabella and horizontal forehead frown lines. “X” marks typical injection sites to reduce glabella and forehead rhytids.

As botulinum toxin is beneficial for wrinkles caused by muscular contraction, it is not suitable for the ‘static wrinkles’ associated with photoageing and dermal collagen loss, for which laser and dermal fillers are more effective. It is therefore most commonly used in younger patients. Potential side effects include bruising, ptosis and an asymmetrical or unwanted appearance, but fortunately these go away as the effects of the toxin wear off. Patients should be instructed to avoid massaging the area as diffusion of the botulinum toxin can lead to weakness of muscles adjacent to the injected site. Botulinum toxin is also used to treat hyperhidrosis (p. 167). Contraindication to the use of botulinum toxin include patients with known hypersensitivity to any component of the formulation, those with neuromuscular disorders such as myasthenia gravis, pregnant or lactating women and patients on aminoglycoside antibiotics.

Dermal fillers

‘Wrinkles at rest’ respond poorly to botulinum toxin. The underlying cause here is a loss of elasticity and volume in the dermis and subcutis: and the aim of using dermal fillers is to replace that volume. The ageing face is characterized by loss of volume in the temple, cheeks and peri-oral area and deep wrinkle lines along the nasolabial folds and corners of the mouth. Dermal fillers can fill in specific furrow lines but also revolumize the sunken, sagging face which results in a more youthful appearance. An ideal filler would be non-inflammatory, non-allergenic, non-carcinogenic, non-migratory, long-lasting and provide a natural appearance. However, no such product exists and there are few trials comparing the different agents.

Fillers are based on naturally derived or synthetic polymers – usually of collagen or hyaluronic acid. Most are injected into the upper or mid-dermis and are useful for wrinkles at rest, acne scars and wrinkles in the lower two-thirds of the face where botulinum toxin is less effective. They are commonly used for the nasolabial folds (Figure 22.2), ‘marionette lines’ (which radiate from the lateral border of the mouth to the chin), crow’s feet and for augmenting the lips.

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