SAN DIEGO – .
“Men generally have larger facial muscle mass,” Dr. Green, a dermatologist in Coral Gables, Fla., said at the annual Masters of Aesthetics Symposium. “We need a higher dose to treat them, or they will not be happy. In general, I try to increase the dose by about 50% for my male patients.”
Dr. Jeremy B. Green
Two early trials of dose adjustments support this practice, he said. In one, 80 men were randomized to receive a total dose of either 20, 40, 60, or 80 U of botulinum toxin type A (Botox) in the glabellar area. The researchers found that the 40, 60, and 80 U doses of botulinum toxin type A were consistently more effective in reducing glabellar lines than the 20 U dose.
In a subsequent study, researchers administered botulinum toxin type A (Dysport) 0.5 to 0.7 mL for men (60, 70, or 80 units), based on procerus/corrugator muscle mass. Efficacy was assessed by a blinded evaluator and patient self-evaluation at several time points up to 150 days post treatment. The median duration of effect was 109 days vs. 0 days for placebo in the blinded evaluator evaluation and 107 days vs. 0 for placebo in the patient self-evaluation.
Most injection algorithms for treating the glabella rely on a 5- or 7-point injection technique, but in 2021, researchers led by Sebastian Cotofana, MD, PhD, of the department of clinical anatomy at Mayo Clinic, Rochester, Minn., reported results from a study of the efficacy and safety of a refined 3-point injection technique targeting horizontal and vertical lines to prevent brow ptosis.
“Prior to this study Sebastian asked me, ‘Why do you guys always inject the body of the muscle?’ ” Dr. Green said. “‘If you inject the origin of the muscle on bone, you could more effectively wipe out the entire muscle’s movement. You’re going to get a better result at a lower dose, so let’s study this.’”
The injection technique involves targeting the midline level of the connecting line between left and right medial canthal ligaments with a 90-degree injection angle with bone contact, as well as the medial and inferior margin of eyebrows with a 45-degree injection angle in relation to midline with frontal bone contact. These three points are located inferior to the traditional (on-label) glabellar frown line injections used to treat the frontalis and the brow depressors.
The researchers used the 5-point glabellar line severity scale to evaluate the time of effect onset and the injection-related outcome 120 days after the treatment in 27 men and 78 women. They found that the onset of the neuromodulator effect occurred in an average of 3.5 days, and no adverse events such as eyebrow ptosis, upper eyelid ptosis, medial eyebrow ptosis, and lateral frontalis hyperactivity occurred during the study period.
“If you inject the origin of these muscles, you can get a brow lift with this technique by avoiding frontalis altogether,” Dr. Green said. “The caveat is, it’s so great at lifting the brows that if you treat the forehead, you may create a midline horizontal ‘shelf’ like I’ve never seen before, where the eyebrows elevate into an immobile superior frontalis.”
To avoid this when treating the forehead as well, he’s learned to split the dose of neuromodulator. “If I was injecting 5 units in the procerus before, I’ll do 2.5 units on nasal bone at the insertion of the muscle and then 2.5 units higher up in the traditional midline procerus injection site,” Dr. Green said.
“Same with the corrugators,” he continued. “Then, remember to inject more superficially in the lateral part, the tail of the corrugators, because the tail of the corrugators is inserting into the undersurface of the dermis. That’s why you see that skin puckering in the lateral brows when people frown. You’re pretty safe to chase that laterally if the brow’s already flat as in men, but I caution you [not] to do that in women, because you may flatten the brow.”
Dr. Green said that he is aware of two cases of lid ptosis from the 3-point technique, one of which happened to him.
“When you’re on the bone with your thumb you can feel that liquid traveling along the bone,” he said. “It can travel all the way to the midline pupil where the levator palpebrae superioris muscle is. I now don’t come in contact with bone with my corrugator origin injections, but rather float the needle a couple of millimeters off bone (in muscle) to hopefully prevent that from happening. Alternatively, some people will compress the brow along frontal bone lateral to that corrugator injection site while they’re injecting to prevent backflow of the neuromodulator.”
Dr. Green reported having received research funding and/or consulting fees from many device and pharmaceutical companies.