Dr Maas: Masseteric hypertrophy broadens the lower face and can be seen in people of Asian descent and those with bruxism. BTXA injection to reduce masseteric mass alters the shape of the lower face, thereby creating a narrower contour that is more aesthetically pleasing in women and can also treat bruxism. I believe that some benefit might be due to a reduction in parotid gland size, although imaging studies are required to confirm this idea. Because bruxism can lead to dental trauma, pain, and temporomandibular joint dysfunction, patients with masseteric hypertrophy suspected to be related to bruxism should be referred for dental evaluation if they are not already under a dentist’s care.
The patient in this case was treated with a high dose of onaBTXA because I knew her well and was comfortable starting at this dose. Typically, I will use just 20 U per side for initial therapy. Then, I will increase the dose by 10-U increments to a maximum of 40 U when the patient returns for repeat treatment after the benefit has disappeared. I use a 31G short needle and keep the delivery posterior, staying away from the anterior border of the masseter to avoid hitting the facial nerve.
Dr Yoelin: Injections for masseteric hypertrophy should be kept posterior to avoid weakening of the risorius, zygomaticus major, and zygomaticus minor muscles, which could result in an asymmetric smile or the appearance of facial paresis. Weakening of the masseter itself usually does not interfere with the ability to chew because several other muscles are also used for mastication.
Older patients, in particular, might be at risk for developing skin laxity after BTXA injections that reduce the space occupying masseter muscle mass. Filler injections along the ramus, angle of the mandible, and even the lateral portion of the mandible can correct this issue.
ABOUT CASE 6
From the Files of Shino Bay Aguilera, DO, FAAD
A 55-year-old white female requested neck-skin rejuvenation and lifting (Figure 7A). She was treated with 30 U of incoBTXA, with 15 U per side distributed evenly across 15 sites (Figure 7B). The injection was delivered deeper on the jawline and with a microinjection technique into the dermis on the neck. With this technique, the first 3 injection sites are along the medial fibers of the lower border of the mandible. Then, the patient was asked to grimace to expose the platysmal bands, and a total of 3 U was injected down along the bands 1 cm apart for a total of 9 injection sites along the lateral fibers of the platysma. Each injection site received 1 U separated by 1 cm, as illustrated in Figure 7A. Alternative treatments would be 30 U of onaBTXA or praBTXA-xvfs and 75 U of aboBTXA. Figure 7C shows the patient’s appearance after treatment.
Dr Aguilera: The Nefertiti lift redefines the jawline using deep injections into the platysmal bands and intradermally along the mandibular border and upper neck.31 This patient was treated with a variation of the Nefertiti lift, one that I find provides more enhanced lifting by relaxing the posterior lateral fibers of the platysma.
Dr Cohen: The Nefertiti lift was quite popular in 2007 for a few years after Phil Levy, MD, described it. In my experience, it is rarely a standalone success along the jawline. I think BTXA can soften platysmal bands that are present at rest quite nicely (particularly in people who have had a neck lift or recent submental fat minimization treatment). However, I find jawline contouring to be especially enhanced with the use of a lifting filler (such as a calcium hydroxylapatite or hyaluronic acid dermal filler) in the prejowl sulcus as well as along the postjowl jawline. In addition, some patients show a nice added improvement to the jawline with the use of microfocused ultrasound or radiofrequency in the lateral jawline.