Platysma, nefertiti lift, and beyond

Summary and key features

The aging lower face and neck are characterized by a number of features, including loss of jawline contour, vertical banding, horizontal line formation, dyschromia and texture complaints, tissue redundancy, and loss of elasticity. The aging neck is a growing concern among patients and has become as bothersome as lateral canthal lines.
The role of the platysma in the aging of the lower face is more complex than previously appreciated as it interdigitates with many muscle groups. Its role as a depressor is a significant contributor to the evolution of the inverted triangle, a key paradigm associated with the aging face.
The anterior and posterior boarders of the platysma, which become more prominent as we age due to skin atrophy and lipoatrophy, create vertical bands , while repetitive contraction of the platysma, which pulls the neck skin medially, creates lines perpendicular to the direction of the vertical muscle fibers, that is, horizontal neck lines .
An emerging patient complaint is prominent horizontal neck creases caused or exacerbated by the repetitive positional behavior of looking down at a cellphone (“tech neck”).
The use of neuromodulators in the lower face can restore contour, soften lines, reduce banding, and can even address texture irregularities. As such, the use of neuromodulators in the lower third of the face and neck has become a mainstay of treatment.
The recognition of global aesthetic outcomes has led experts to recommend the use of neuromodulators for the lower face and neck as part of a multimodal treatment plan including other minimally invasive treatment strategies, such as dermal filler, cryolipolysis, sodium deoxycholate injections, and laser and energy-based devices.

Introduction

As we age, the changing appearance of the face and neck is bothersome to many patients. Characteristics of aging in these regions are multifactorial and dynamic, involving alterations to the skin and underlying soft tissue, bone, muscle, and fat. Chronic ultraviolent (UV) exposure contributes to skin atrophy and texture alterations and induces vascular and pigmentary changes. The skin becomes lax and redundant due to the depletion of collagen and elastin (also partially UV-induced). The youthful triangle of the face becomes reversed as the downward vector of gravity exacerbates changes in the jawline and neck over time ( Fig. 22.1 ). Bony prominences, which provide structural support, atrophy and elongation of the lower face ligaments allows for inferior displacement of facial fat compartments, leading to sagging skin, accumulation and/or redistribution of submental fat, and loss of jaw definition and contour. In the neck specifically, muscle hypertrophy and increased resting tone of the platysma, coupled with persistent muscle contractions, lead to horizontal lines, or wrinkling, of the overlying integument. Dermal and subcutaneous atrophy further highlight the platysmal hypertrophy and separation, particularly during movement, presenting as prominent vertical bands ( Fig. 22.2 ).

Fig. 22.1, The youthful triangle of the face and its inversion over time.

Fig. 22.2, Platysmal banding highlighted by progressive dermal and subcutaneous atrophy.

As our understanding of contributors to lower face and neck aging has evolved, an increasing number of noninvasive treatment strategies have emerged. A customized multimodal approach is recommended and may include neuromodulators, dermal filler, cryolipolysis, sodium deoxycholate injections, laser and energy-based devices, among others. In this chapter, we will focus on the role of neuromodulators to delay and manage changes related to aging of the neck and lower face.

Anatomy

The platysma is comprised of two broad and flat muscular components that cover the anterior and lateral aspects of the neck and serve as a key muscular contributor to the structure and function of this anatomic area. This muscle arises inferiorly from the anterior chest, inserting into the superficial fascia of the pectoralis and deltoid muscles. It then ascends superomedially, partially inserting into the underside of the periosteum of the mandible, with remaining fibers continuing superiorly. Some of its fibers then insert into the modiolus while the remaining platysma fuses, at its most cranial position, with the subcutaneous musculoaponeurotic system (SMAS). The facial component of the platysma, frequently referred to as the upper platysma, is described in three parts: (1) pars mandibularis, which inserts onto the lower border of mandible and onto the skin and subcutaneous plane of the lower face, some fibers interdigitating with the depressor anguli oris (DAO) and mentalis muscles; (2) pars labialis, which travels deep to DAO, interdigitates, and blends to orbicularis oris, risorius, depressor labii inferioris (DLI), and mentalis muscles and in some cases occupies the space between the DLI and DAO; and (3) pars modiolaris, which includes all remaining fibers of upper platysma that are posterolateral to the DAO ( Fig. 22.3 ). Given these complex and varied insertions with bone and muscles of the lower face, the platysma functions as a major depressor, pulling down bilateral oral commissures and cheeks, exacerbating marionette and lateral cheek lines.

Fig. 22.3, Cadaveric dissection of the facial components of the platysma muscle, demonstrating (A, B) pars mandibulairis, (A) pars labialis, (B) pars modiolaris.

In the neck region, contraction of the platysma leads to compression of the overlying skin in a manner that is comparable to that of a compressed accordion. Repetition of this movement leads to the development of horizontal neck wrinkles, also called necklace lines, which lie perpendicular to the direction of the underlying, vertically oriented muscle fibers. These horizontal rhytids are static and dynamic, such that they are visible during muscle contraction and while at rest. The anterior and posterior platysmal borders, which become more visible as the skin and subcutaneous tissue atrophy as we age, are responsible for vertical banding. While the vertical bands often tighten and become more prominent when the neck is animated, they can also be seen at rest due to increased muscular resting tone.

Botulinum toxin

Botulinum toxin type A (BoNT-A) has been particularly useful as a treatment modality to manage anterior vertical bands, to soften horizontal neck lines, to improve or restore jawline definition, and texture complaints. Targeted neurotoxin to the lower face for the purpose of contouring was first reported in 1999 by Matarasso et al. Brandt and Bellman later showed that high dose regimens of onabotulinumtoxinA tightened and recontoured the jawline and cervicomental angle, improved skin laxity of the neck, and addressed banding and lines. However, the high doses (up to 200 U) required for efficacy led to an increased incidence of adverse events, including difficulty swallowing, neck weakness, asymmetric smile, dysphonia, or difficulty breathing, which can be life-threatening. These undesirable effects are due to the diffusion of toxin into underlying muscles such as the sternocleidomastoid. Despite the excellent results seen with this technique, after discussion at several consensus meetings, experts recommended a dramatic reduction in the total dosage injected per session, usually no more than 50 units of onabotulinumtoxinA. In 2007, Levy introduced the “Nefertiti lift,” a lower dose regimen that focused on redefining the jawline in which individuals were injected horizontally along the lateral edge of each mandible and in the upper portion of the posterior platysmal bands. As a result, most of Dr. Levy’s cases achieved visible release of the downward pull on the face by the platysma, successful recontouring of the jawline, and elevation of the bilateral oral commissures.

Patient selection

Proper patient assessment and selection is important to optimize neuromodulator treatment outcomes of the lower face and neck. Ideal candidates include those with platysmal hyperactivity whose retaining ligaments are intact, with adequate skin elasticity and minimal descent of submental fat. Alternatively, patients who are surgical candidates for rhytidectomy, platysmaplasty, or liposuction tend to have suboptimal outcomes with a neuromodulator approach.

Clinically, we can predict who may respond by asking patients to frown, grimace, or clench their teeth and observing their individual muscle movement during these maneuvers. If the platysmal bands become obvious, then the injector can feel comfortable that they will be able to target the underlying tissue effectively.

Treatment techniques

After removing makeup and cleansing the skin with topical antiseptics, a topical anesthetic cream and/or ice may be applied for the comfort of the patient and kept in place for up to 30 minutes.

Though reconstitution of neurotoxin varies, we typically recommend diluting a 100-U vial (Botox®/Xeomin®) in 2 mL of preserved saline solution for a final concentration of 50 U/mL. AbobotulinumtoxinA (AboBoNT-A), which requires 2.5 times the units of onabotulinumtoxinA (OnaBoNT-A), is diluted comparably, so the injection volume is the same regardless of the product used.

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