Several panel members mentioned they are getting very good results with prabotulinumtoxinA-xvfs for treating masseter hypertrophy, perhaps somewhat better than with other BoNT-As. They related that such results were difficult to explain, given that some diffusion would seem beneficial. They suggested the agent may be spreading mechanically due to vigorous muscle action. In addition, it was stated that more effective aesthetic injections of prabotulinumtoxinA-xvfs require deep injection in the masseters to prevent superficial herniation when patients clench, chew, or bite.
Panelists discussed 2 ways of shrinking the masseter. For example, in Asian women who are really looking for facial shaping and masseter reduction, some clinicians use 30 to 45 units or more of onabotulinumtoxinA or prabotulinumtoxinA-xvfs per side in a single visit to shrink the masseter quickly. The other option is to use fewer units and shrink it slowly over time. This allows titration over time and prevents jowling or masseter atrophy from high-dose treatment, but results don’t usually last as long.
The platysma is a broad, thin muscle that covers the lower face, throat, and upper chest, and can raise bands on the neck upon contraction.27 Although classically depicted as a distinct muscle on either side of the anterior neck, fibers often decussate across the midline.29 Injections of the platysma in different locations in the lower face and neck with BoNT-A can attenuate lower face rhytides, soften platysma bands, improve the shape of the jawline, and diminish horizontal neck lines.40 By reducing the degree of downward pull, injection of the platysma can also improve lateral cheek lines and marionette lines, lifting the lower face.39 Care should be taken to inject specifically into the bands, as diffusion of BoNT-A to other muscles of the neck can cause difficulty swallowing, neck weakness, asymmetric smile, or life-threatening breathing difficulties.27,29 Observed muscle action is the primary factor for determining the location of injections, although superficial landmarks, muscle palpation, and anatomic diagrams may be useful.27 Platysma bands can be identified by having the patient grimace and jut out the lower jaw.
The amount of BoNT-A for treating the platysma is highly variable, depending in part on the muscle mass, the number of prominent bands, and the length of the neck.39 Less important factors include desired degree and duration of effect, wrinkle severity, and adjacent muscle function.27 While the panelists had a variety of injection techniques, they agreed that just “chasing” platysma bands is not effective. The more recent trend is to use BoNT-As as sculpting agents through paralysis. Several member of the group grasp the contracted band and inject BoNT-A very superficially every 1 to 2 cm down the length of the band to the clavicle. One group member related how crucial it can be to include injection with 5 or so units where the platysma merges with the mandible, and triangulates, perhaps because treatment is shrinking the maxillary salivary gland.
Recruitment can be an issue in the platysma since it is such a wide muscle. In a study by Matarasso and colleagues of 1,500 patients treated in 3 different practices, one of the authors used up to 250 units of onabotulinumtoxinA in some necks, which caused a significant degree of dysfunction in some patients.41 Panel recommendations to help prevent adverse events in this area include staying away from the midline when injecting. In addition, it was suggested that higher doses in the lateral part of the band, which are affecting the jowl, can provide great results with a proper safety margin.
The group agreed that treated correctly, the platysma can be an area of high patient satisfaction, although patients may consider it as being expensive. If a patient is budget-conscious and they are concerned about the cost of treating the entire platysma, it makes sense to treat them with a few units on each side, which can help with jowling. Many patients are not aware that it is possible to define the jawline with BoNTs. When patients notice their jowls improving, they often come back for treatment of the entire platysma. Another option is to treat the platysma at every other patient visit, or every 6 to 9 months, which amortizes the price over time. That’s possible because results can last longer than in other areas. A little soft tissue filler along the jawline on the same visit can also improve results.
The group agreed that a limited and carefully selected population of patients can benefit from treatment of the platysma from the mandibular border to the corner of the mouth (Nefertiti neck lift) to weaken the depressor action of the top part of the platysma and augment the elevator action, redefining the jawline and reducing neck rhytides.32 Best patients typically have good retention of tissue quality and palpable platysma muscle mass, especially posteriorly, with a band that obscures the mandibular border when platysma is contracted while the patient is seated. In many cases, combining this technique with injection of individual platysma bands produces superior results.
VALUE OF COMBINATION THERAPY
The group agreed it is impossible to resolve all facial aesthetic issues with just BoNT-As. Combination treatment with soft tissue fillers is now considered standard of care.14 While the original paradigm was to relax the upper face, fill the midface, and relax and fill the lower face,42 this has evolved toward more equal use of BoNT-As and fillers throughout the face. BoNT-As