NEW YORK — Botulinum toxin is currently used on- and off-label for various medical and cosmetic indications. One off-label cosmetic indication that is growing in popularity is the treatment of masseter and glandular hypertrophy when performing aesthetic facial contouring.
"Masseter muscle reduction is a procedure often requested by Asian ethnicities and more commonly in the Korean population. The surgical techniques employed to reduce masseteric or parotid and submandibular glandular hypertrophy can be brutal and can be associated with sometimes severe complications and a long recovery period," says Michael Kane, M.D., plastic surgeon and associate attending surgeon, Manhattan Eye, Ear and Throat Hospital, New York. "The use of botulinum toxin can effectively treat the hypertrophy and circumvent unwanted surgical trauma and complications."Upon examination, patients will bite down and the physician palpates for and localizes the masseter hypertrophy. While holding the anterior and posterior aspects of the masseter muscle, the surgeon injects botulinum toxin into the protruding muscle bulk. Though many different injection techniques have been postulated — including four- or five-point injection patterns such as that on a die — Dr. Kane says masseter hypertrophy can vary from patient to patient, so one should inject the toxin only where the hypertrophy is felt and not in a predetermined injection pattern.
INJECTION TECHNIQUES When injecting the hypertrophic masseter muscle, Dr. Kane says he tends to use much lower unit doses than other physicians, injecting 10 to 25 units of Botox (onabotulinumtoxinA, Allergan) per side for the masseter, with a median dose of 15 units per muscle. Using Dysport (abobotulinumtoxinA, Medicis), Dr. Kane typically uses a median dose of 40 units per masseter muscle, he says.
One adverse event that can occur after injecting botulinum toxin into the hypertrophic masseter muscle is a cheek dent or cheek indentation, which typically can be seen in the posterior cheek area along the anterior border of the masseter muscle. According to Dr. Kane, this unwanted side effect is often the result of injecting a normal, nonhypertrophic masseter muscle with botulinum toxin, and it can occur when a predetermined four- or five-point injection technique is followed.
"In my opinion, injecting botulinum toxin into the masseter muscle hypertrophy using a predetermined injection pattern is an error. I think that these standard injection patterns waste a lot of toxin and actually weaken part of the masseter that is not involved in the hypertrophy, thus often resulting in an unwanted indentation of the cheek," Dr. Kane says.
INJECTING GLANDS Injecting botulinum toxin in the parotid or submandibular glands can also prove to be a useful tool when addressing and correcting the unwanted sequelae of a poor facelift, particularly one that results in trauma to the parotid gland. Dr. Kane has used this technique in many patients who were referred to him following facelift mishaps, again using a median dose of 20 units for Botox and 50 units for Dysport to treat the parotid gland.
"Sometimes, a surgeon may nick the outer shell of the parotid, which may result in a draining fistula or a large cavity which will fill up with parotid fluid. In these cases, I inject the parotid to quiet down the production of the gland and decrease its output, allowing the area to heal much faster," Dr. Kane says.
In some patients, the submandibular glands can be enlarged or low-seated in the neck, making their protrusion more apparent. The glands can be more pronounced following a facelift after the removal of fat and tightening of loose skin as well. Botulinum toxin can be very useful in improving the contour of the submandibular region in these patients, Dr. Kane says.
"The glands will not disappear after the injection, but you can soften and improve the contour of the neck. Here, I will typically give about 15 units of toxin into the gland, typically at one injection point for a good aesthetic effect," he says.
LONGEVITY Whether given in the masseter, parotid or submandibular regions, the cosmetic outcome of botulinum toxin injections can last approximately six to eight months. According to Dr. Kane, however, the more often the procedure is performed, the longer the cosmetic effect lasts, in some cases as long as one year.
Exceptions to the longevity of Botox masseter correction would be patients who are teeth grinders, because here, the masseter will consistently revert towards a hypertrophic state. Such patients may have a cosmetic effect lasting approximately four to six months, Dr. Kane says.
Disclosures: Dr. Kane is a consultant, speaker and stockholder for Allergan, Medicis and Revance, and is a consultant for Merz.