ORLANDO – Dose is the most important consideration when injecting botulinum toxin in the lower face – even more important than during treatment of the upper face, according to Dr. Doris Hexsel.
"You should always use the lowest effective dose in the lower face," said Dr. Hexsel. This strategy reduces the risk for asymmetry, muscle dysfunction, and temporary oral paralysis. "These are dose-related and technique-related side effects."
Botulinum toxin can treat perioral wrinkles and marionette lines, as well as improve the appearance of a patient’s chin or gummy smile. However, only treat one or two areas in the lower face during the same session to minimize the risk of "sum of effect," she said. In other words, the effects of multiple, simultaneous injections around the mouth can be cumulative.
Also consider a combination of the botulinum toxin and filler injections, Dr. Hexsel said at the annual meeting of the Florida Society of Dermatologic Surgeons.
Dr. Hexsel shared her expertise with botulinum toxin for the following indications:
• Perioral wrinkles. Injections should be superficial and at least 1.5 cm from the corners of the mouth. Any closer and you increase the risk of undesirable relaxation of the depressor anguli oris muscle, the zygomaticus major muscle, and the risorius muscle, said Dr. Hexsel of the department of dermatology at Pontificia Universidade Católica do Rio Grande do Sul, Brazil.
She said that she typically injects 1.25 U-2.5 U abobotulinumtoxinA (Dysport, Ipsen/Medicis) per point, or 0.5 U-1.0 U onabotulinumtoxinA (Botox, Allergan). With two to six injection points, the total dose varies from 4 U-18 U for abobotulinum toxin or 4 U-10 U for onabotulinumtoxinA.
As a bonus, she said, "We observe a slight increase in the volume of the lips due to just the relaxation."
• "Cellulitic chin." Loss of collagen and subcutaneous fat, along with action of the jaw muscles, can cause a chin to have a cellulitic or "peau d’orange" appearance. Botulinum toxin can treat this area as well, said Dr. Hexsel. "I prefer two point injections – bilaterally at the most distal point of the mentalis muscle.
Again, keep the injections superficial and avoid high doses to minimize undesirable relaxation of the depressor labii inferioris muscle, she said. The total dose for a dimpled chin ranges from 15 U to 20 U of abobotulinumtoxinA and from 5 U to 10 U of onabotulinumtoxinA.
"I touch up patients 15 to 30 days later, if necessary," she added.
• Marionette lines. Botulinum toxin can improve the appearance of patients when the corners of their mouth appear permanently turned down. Better results may be obtained by combining toxin with fillers, she said.
For mild presentations, treat the mentalis muscle first, she advised. Treatment of this muscle also recruits the depressor anguli oris (DAO) muscle less (the mentalis is the agonist muscle to the DAO). Dr. Hexsel said she generally uses a total dose of 10 U-20 U of abobotulinumtoxinA or 3 U-6 U of onabotulinumtoxinA for this indication.
• Gummy smile. Consider botulinum toxin when a patient complains of a gummy smile. To foster a more natural look, also treat any natural asymmetries or posterior gummy smile, Dr. Hexsel said.
To treat posterior gingival exposure, inject two points on either side of the malar region. Inject in the nasolabial fold at the point of greatest lateral contraction during a smile.
Total doses vary from 5 U to 15 U of abobotulinumtoxinA or from 4 U to 10 U of onabotulinumtoxinA.
A final tip is to take before and after clinical photos, both during movement and at rest, when injecting the lower face.
Dr. Hexsel reported receiving grants and research support from Allergan, Galderma, and Ipsen. She also is a consultant for Allergan and Ipsen.