Treatment of orbicularis oris, mentalis, depressor anguli oris with neuromodulators

Summary and key features

The aging lower face is characterized by perioral rhytides, flattening of the lips, development of deep marionette lines, oral commissures, and pebbling of the chin.
While its use is currently off-label for the lower face, botulinum toxin type A has been successfully used for lower facial rejuvenation.
Treatment of the lower face targeting the orbicularis oris, mentalis, and depressor anguli oris with neuromodulators is an effective, noninvasive, and increasingly popular procedure with a low risk profile.
It is important to inquire about relevant hobbies and professions (i.e., musicians, singers, frequent public speakers) prior to treatment of the lower face with neuromodulators, as treatment can affect lip function.
Proper injection technique is paramount to optimize treatment outcomes and avoid adverse effects due to unwanted paralysis of adjacent structures.
Botulinum toxin type A leads to significant improvement as monotherapy and may even enhance cosmetic outcomes when used in combination with other treatments, including soft tissue fillers and/or light, laser, and energy-based devices.

Introduction

The face undergoes notable changes with age, resulting in specific characteristics of the aging upper, middle, and lower face. Bony remodeling, volume loss, deterioration of skin quality and padding, inferior descent of fat, and weakening of retained ligaments contribute to the progressive manifestations of aging in the perioral region, jawline, and chin. The lips flatten, the oral commissures turn downward, forming deeper marionette lines, and the chin develops a pebbled appearance due to repetitive mentalis activity and loss of underlying subcutaneous fat ( Fig. 21.1 A and B). Therefore, rejuvenation of the lower face involves control of muscle hyperactivity and restoration of volume loss. Botulinum toxin type A helps to control muscle hyperactivity and has been shown to successfully rejuvenate the appearance of the aging lower face by improving the appearance of perioral rhytides, pebbling of the chin, marionette lines, and oral commissures. In addition to reducing muscle hyperactivity, botulinum toxin may also contribute to lower face rejuvenation via dermal neocollagenesis as prior studies have demonstrated increased levels of procollagen type 1 carboxyterminal peptide levels in dermal fibroblasts, upregulation of type 1 collagen, and reduction of matrix metalloproteinase production following injection of botulinum toxin. Currently, there are four formulations of botulinum toxin type A available and approved by the United States Food and Drug Administration (FDA), including onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and prabotulinumtoxinA. DaxibotulinumtoxinA is a newer formulation of botulinum toxin type A in clinical development for aesthetic and therapeutic indications, shown to be safe and effective for the treatment of moderate or severe glabellar lines in phase 3 trials (SAKURA 1, SAKURA 2, SAKURA 3). Of the currently available formulations, onabotulinumtoxinA has been the most extensively studied, although all formulations appear to be equally effective and safe when used for aesthetic indications. Botulinum toxin type A injection is notably one of the most common aesthetic procedures performed in the United States. According to the 2019 American Society of Dermatologic Surgery survey on Dermatology Procedures, the number of botulinum toxin type A treatments has increased by 60% since 2012, with 2.3 million procedures performed in 2019. While onabotulinumtoxinA is currently only FDA approved for aesthetic indications in the upper face (i.e., glabellar lines/crow’s feet/horizontal forehead lines), it has been successfully used off-label in the lower face in limited studies and clinical practice. In addition, and more importantly, treatment with botulinum toxin type A has led to improvement in patient-reported outcomes, with positive effects on perception of youthfulness, attractiveness, mood, and self-confidence. Monotherapy treatment with neuromodulators for the lower face offers many benefits, including the noninvasive nature of the procedure, notable efficacy, and low risk profile. However, understanding the anatomy of the lower face, appropriate dosing, and proper injection technique are paramount to preventing common adverse effects that may occur following treatment. This chapter will discuss treatment of the orbicularis oris, mentalis, and depressor anguli oris (DAO) with neuromodulators ( Fig. 21.2 ), focusing on common pitfalls and recommendations for optimizing outcomes (see , , ).