With the U pattern, there is medial brow depression, which is caused by corrugator contraction. I find that patients with this pattern have a short corrugator muscle and require little or even no injection into the distal/lateral end of the corrugator. Injecting BTXA at 3 sites concentrated in the center would probably lift the medial brow.
The inverted-omega pattern has a deep nasal root crease as a distinguishing feature. Treatment of patients with this pattern would include a standard 5-point injection plus a nasalis injection to address the deep nasal crease, thereby resulting in a 7-point injection pattern.
Dr Yoelin: Achieving the best results for each patient requires individualizing the approach to BTXA injection. In addition, assessing individuals on animation is critical because this will guide injection placement. Lastly, the doses used take into account muscle mass or strength.
Dr Cohen: Data from cadaveric studies show that the medial corrugator is much thicker than the lateral corrugator.24 This information argues against injecting equal doses medially and laterally into the corrugators when treating glabellar lines.
Dr Gold: The informed consent that patients sign should mention all possible complications because health care practitioners who perform enough BTXA injections can expect to encounter every potential complication at some time. Bruising is the most common complication after a BTXA injection, and it can be persistent. Treating bruising with energy-based devices, including ultrashort-pulse Nd:Yag (neodymium-doped yttrium aluminum garnet) lasers and pulsed-dye lasers, has been widely accepted as an option to make posttoxin bruising diminish faster than time alone.25 I use a short-pulsed 1064-nm laser to reduce postbruising time, and have observed nice results in my patients.
Dr Yoelin: I try to use a 33G needle for my injections because I think the thinner needle reduces the risk for bruising.
Dr Cohen: Eyelid ptosis is an uncommon complication after treatment of glabellar lines. It is thought to result from BTXA diffusion from the lateral corrugator injection site through the orbital septum to the levator palpebrae superioris, which elevates the upper lid. The ptosis typically appears 3 to 7 days postinjection, lasting 2 to 4 weeks.26
Eyelid ptosis can be managed with an ophthalmic alpha-adrenergic agonist drop to contract the Müller muscle.27,28 Products are available over the counter (naphazoline) or by prescription (apraclonidine). The prescription medication can be more effective, but not all pharmacies stock it. Having a supply of the over-the-counter drop in the office provides a convenience for patients who might need treatment for eyelid ptosis.
Avoiding BTXA injections below the orbital septum or at or under the midbrow can help minimize the risk for eyelid ptosis. Care should be taken if there is concern about integrity of the orbital septum in older patients, those with a history of lid surgery or traumatic injury, and patients who experienced lid ptosis after previous BTXA treatment.
Brow ptosis can also occur. Preventive measures include being conservative in frontalis dosing when treating older patients and avoiding treatment of the frontalis altogether in patients with more advanced degrees of dermatochalasis (brow-lid redundancy, in which the lid is literally touching the lashes at baseline). Another instance is in those with prior brow ptosis who have experienced neuromodulator therapy.
With descent of the medial brow and lifting of the lateral brow, a “Spock-like”, Mephisto, or devil-like appearance might also occur, especially when using the standard 5-point injection in men, who tend to have strong frontalis muscles. The problem could be prevented by treating these men with a 7-point injection technique that includes lateral frontalis injections. Undesired or excessive lateral-brow lift can be corrected by injecting a small dose of BTXA (eg, ≤ 1 U of onaBTXA) into the lateral frontalis.
Widening of the interbrow distance is another possible complication of corrugator muscle weakening after glabellar-line treatment. There is no known therapy for this problem, and its potential should be discussed with patients, particularly those who already have wide spacing between their eyebrows.
To minimize the risk of potential unwanted migration of neuromodulators, which can lead to complications such as eyelid ptosis, I instruct patients to avoid yoga or other activities in which they would invert the head during the first couple of hours after their injection.
Dr Yoelin: When recommending an alpha-adrenergic agonist to treat lid ptosis, I tell patients to put a drop of the medication in the affected eye(s), gently close the lids, and keep them closed for approximately 15 seconds without blinking. This promotes contact of the medication with the Müller muscle and minimizes drainage through the lacrimal duct, which can lead to systemic absorption and side effects.