Botox injections are well known to effectively reduce unwanted wrinkles and folds in the skin that are caused by facial muscle movement. This is why Botox is known as a dynamic wrinkle reducer. While Botox has been used all over the face and neck, its use around the eyes is by far what most people seek to treat. Glabellar furrows, horizontal forehead creases and crow’s feet constitute the vast majority of neuromuscular modulation, whether it is done by Botox, Dysport or Xeomin.
But any facial muscle whose action is problematic, either causing cosmetic distortion or pain, can be treated. One of these uncommon areas is the chin in the management of mentalis muscle spasm, strain or hyperkinesis. The mentalis muscle is the dominant muscle of the chin as it crosses in front and over it. It is a paired muscle that originates on the chin bone and extends upward to insert into the lower lip tissues. Its action is to primarily lift and protrude the lower lip or to make a pout. As a result, it also wrinkles the skin of the chin and can make the labiomental fold between the lower lip and the chin deeper. Abnormal mentalic muscle movements can create unaesthetic dimpling of the chin or even hyperkinetic movements known as geniospasm.
The mentalis muscle can be weakened or denervated by Botox injections to treat abnormal mentalis muscle movements. The injection points are best done just above the inferior border of the mandible, where the muscle originates, on both sides about one cm. off the midline. Some may prefer to do central chin injections but it is important to remember that the paired nature of the mentalis muscles often leaves just a fat pad between them in the midline unless one injects fairly high. The dose injected should be 4 to 8 units per side with a total of no more than 16 to 20 units for the entire chin.
Like all Botox injections, it takes a week to see its full effect. Its effects will also last just as long as anywhere else on the face of around four months. Decreased chin dimpling, central straining and a more shallow labiomental crease are the treatment objectives. I have seen a few cases where the mentalis muscle has been completely paralyzed resulting in abnormal lower lip movements. For this reason, it is usually best to start with a low total dose of 10 to 12 units and add more later if needed. In some cases, Botox injections can be supplemented with injectable fillers for a deep labiomental fold and wrinkles for a more profound overall effect…and may be the perfect recipe for severe chin muscle and wrinkles problems.
Dr. Barry Eppley
Indianapolis, Indiana