21 Botulinum Toxin
Treatment of facial lines and wrinkles (also called rhytids) with botulinum toxin has become the most frequently performed cosmetic procedure in the United States, according to statistics from the American Society for Aesthetic Plastic Surgery.1 It is also one of the most common entry procedures for health care professionals seeking to incorporate aesthetic procedures into their practice.2
Botulinum toxin is a potent neurotoxin protein derived from the Clostridium botulinum bacterium. It reduces muscular contraction through inhibiting release of acetylcholine at the neuromuscular junction. Injection of small quantities of botulinum toxin into specifically targeted muscles causes localized, temporary chemical denervation with resultant muscle relaxation.3
Botulinum toxin has been used for more than 20 years to treat a variety of clinical conditions such as blepharospasm, strabismus, cervical dystonia, hyperhidrosis, migraines, and muscle spasticity.4–6 Botulinum toxin is used in numerous facial aesthetic areas. However, treatment of the glabellar complex,7 frontalis8 and orbicularis oculi muscles,9 which contribute to formation of frown lines, horizontal forehead lines, and crow’s feet, respectively, offers the most predictable results, greatest efficacy, and fewest side effects.10,11 Botulinum toxin treatment of hyperdynamic muscles in the upper one-third of the face are a core aesthetic procedure for providers interested in incorporating aesthetic care into office practice.12
Cosmetic Indications
Alternative Therapies
Botulinum toxin is the only FDA-approved treatment for dynamic wrinkles. Static wrinkles can also be treated with chemical peels, microdermabrasion, topical products such as retinoids, nonablative lasers for soft-tissue coagulation and tightening using infrared and radio-frequency, nonablative lasers for collagen remodeling using 1320 and 1540 nm Q-switched lasers and others, and ablative and fractional ablative lasers using erbium and carbon dioxide. Limited data suggest that an acetylcholine blocker found in topical skin care products, acetyl hexapeptide-8, may reduce wrinkles.13 However, additional studies are necessary to support this finding.
Contraindications
Anatomy
A thorough understanding of facial anatomy in the treatment areas is essential prior to performing botulinum toxin procedures (Figure 21-1). The muscles of facial expression are unique because, unlike most muscles, which have bony attachments, they have soft tissue attachments to the skin through the superficial muscular aponeurotic system. When a muscle contracts, the overlying skin moves with it and wrinkles are formed perpendicular to the direction of the muscle contraction. Figure 21-2 shows lines and wrinkles in the upper one-third of the face and the corresponding underlying musculature.
Glabellar wrinkles, or frown lines, are vertical lines that occur between the medial aspects of the eyebrows. The muscles that contribute to formation of frown lines are the glabellar complex depressor muscles, which pull the brows medially and inferiorly and include the corrugator supercilii, procerus, depressor supercilii, and medial orbicularis oculi (Figures 21-1, 21-2 and 21-3).
Horizontal forehead lines result from contraction of the broad frontalis muscle, which spans the forehead between the temporal fusion lines (see Figures 21-1, 21-2 and 21-3). The muscle fibers are vertically oriented and contraction of this levator muscle raises the eyebrows. The inferior 2-cm portion has the most marked effect on eyebrow height and shape. The goal of treatment in this area is to partially inhibit activity of the frontalis muscle to reduce horizontal forehead lines while maintaining a desirable eyebrow shape and height.
Periorbital wrinkles, commonly known as crow’s feet, result from contraction of the lateral portion of the orbicularis oculi, a thin, superficial muscle that encircles the eye (see Figures 21-1, 21-2 and 21-3). Contraction of the palpebral portion of the orbicularis oculi muscle results in closure of the eyelid. The goal of treatment in this area is to focally inhibit the lateral orbicularis oculi to reduce crow’s feet without excessive orbicularis oculi muscle relaxation.
Many of the muscles of facial expression interdigitate with one another and, while providing treatment with botulinum toxin to one area in isolation will often provide adequate wrinkle reduction results, in some cases an adjacent muscle group may require concomitant treatment to achieve the desired results. For example, the glabellar complex muscles interdigitate to a greater or lesser degree with the frontalis muscle, and treatment of the frontalis in addition to treatment of the glabellar complex muscles may be required to smooth frown lines in some cases14.
Reconstitution
Injectors reconstitute Botox with differing amounts of saline and there is no standardized reconstitution protocol. Botox efficacy is based on the number of units injected rather than the dilution. However, diffusion and the risk of complications are related to greater dilution volumes.15 The author’s reconstitution technique is outlined below.
Handling and Storage
Botox is shipped frozen, on dry ice. Prior to and after reconstitution it should be stored in the refrigerator at a temperature of 2 to 8°C (35.6 to 46.4°F). Prior to reconstitution it may be stored for 24 months. While the manufacturer recommends using Botox within 24 hours of reconstitution, the American Society for Plastic Surgery Botox Consensus Panel recommends using Botox within 6 weeks and notes no loss of potency during that time.3,16