POCUS for Botox & Fillers: Necessary or Excessive?



Botox injections are booming. At least 11 million people have injected their faces with this bacteria-inspired, paralyzing neurotoxin to reduce wrinkles and achieve a more youthful appearance. In addition, over 2.6 million people have injected fillers into their faces to volumize lips, reduce asymmetry, or attain the fickle beauty standard of the times.


Any "lay medical professional" with aspirations of wrinkle zapping power can become a botox "injector" with a 1-day certification course. With such tiny needles (usually about a 30 gauge) injecting such superficial structures, it sounds safe... Right?


Fillers


According to plasticsurgery.org, injectable dermal fillers "can plump thin lips, enhance shallow contours, soften facial creases, remove wrinkles and improve the appearance of scars." Among the many types of fillers, there are calcium hydroxyapatite fillers, that are biosynthetically produced, lowering the risk of allergic reaction and producing a more natural result. There are also hyaluronic acid fillers, which are similar to the cartilage/connective tissue found in our tendons. Hyaluronic acid fillers are reversible with hyaluronidase, which becomes important when they are botched.


Fillers can be injected into lips, chin, cheeks, or anywhere else. They are performed blind (i.e. without ultrasound guidance) with little to no regard for the facial arteries or veins, which...can be a problem.






Shockingly, there have been at least 190 cases of blindness from filler injections reported in the literature (and presumably many more that weren't reported), most commonly from injections to the glabellar complex (between the eyebrows), nose, and nasolabial folds. Most of these cases were irreversible, except for 6 in which hyaluronic acid was used and therefore hyaluronidase injection was able to reverse it.


In another study of adverse events reported to the FDA over 10 years, out of over 5,000 events the most common complications were nodule formation (2952 cases), infection (2575 cases), inflammation (711 cases), allergic complications (594 cases), and vascular complications (590 cases). Of these vascular complications, vascular occlusion occurred in about 3 per 1,000 injections, with resulting downstream tissue - be it eyeballs or skin - suffering ischemia and necrosis. Of course, getting into the retinal artery and causing blindness is the most concerning. As a group of plastic surgeons described it,


under conditions of high-pressure injection, filler product may be driven upward in the ascending vessels and forced retrograde down the vessels exiting the orbit. Once the pressure is released, the filler product is once again carried by the normal arterial pressure gradient and is forced outward from the intracranial regions. During this outflow, filler product may be carried into the central retinal artery (as well as the adjacent arteries that exit the periorbital area), which might result in blindness that is rarely, if ever, reversible.

So...can this be prevented?



Botox


Compared with fillers, botox injections appear to be far safer. There are also many non-cosmetic indications for botox injections with good evidence to support them, such as to treat migraine headaches, bruxism, or hyperhidrosis. Yet complications still arise, like if you accidentally inject directly into the superficial temporal artery when injecting the temporalis and cause a pseudoaneurysm.


POCUS, Botox, & Bruxism


Bruxism and Temporomandibular dysfunction (TMD) is an extremely common complaint among adults (and sometimes kids as well). This chronic, pathologic clenching results in ground-down teeth and pain at the temporomandibular joint, as well as chronic headaches and the need for a night guard.


Botox injection of the masseter and/or temporalis muscle is a very effective treatment, a treatment that some dentists and orthodontists are now offering. But even with such a seemingly simple botox injection, multiple studies have shown that POCUS guided injections result in safer and more effective treatments.


In one small study, half of the patients underwent standard palpation and marking techniques (with injections at the white dots pictured above) while the other half had ultrasound-guided injections.


In 30% of the non-ultrasound-guided cases, the anterior marking was actually outside of the masseter muscle, a big deal considering the fact that just anterior to the masseter lies the risorius muscle which functions to draw your lip laterally and help you smile. Accidentally injecting risorius could result in facial droop and drooling which will last for 2-3 months until the botox wears off, as seen below:


Via Bae et al. 2014

In another 20% of the cases, the muscle was deeper than the standard 30-gauge 8-millimeter needle could reach, which meant the botox injection was only reaching the dermis and not actually entering into the masseter. In those cases, a longer 13-mm needle was needed - something that would not be knowable without ultrasound. They also found that about 50% of the time, a segment of the parotid gland was covering the upper 3rd of the masseter muscle. To the unsuspecting clinician, injecting the parotid with botox could result in irritation and inhibition of the parotid function (i.e. no unilateral saliva production) for 2-3 months.


Another complication that can arise from masseter injections is what is called Paradoxical Masseteric Bulging (PMB), an uneven bulging of muscles on the facial surface that occurs 2 to 4 weeks after injection, especially in male patients with thin facial skin. Its incidence is anywhere from 0.2% to 27%.


Lee et al. 2016. https://www.mdpi.com/2072-6651/9/1/14/htm

PMB is thought to be related to injecting deep to the deep inferior tendon (DIT in the image below) located inside the muscle, preventing the spread of Botox to the superficial part of the masseter:




The fix is simple, just injecting some Botox into the superficial portion above the DIT, however, without ultrasound it's impossible to determine how deep to inject.


In another study comparing ultrasound-guided injections to the standard method, the masseter reduction was greater and the facial contour was improved in the ultrasound-guided group.

Bae et al. 2020. https://www.mdpi.com/2072-6651/12/9/588

These anatomic considerations, techniques, and variants are summarized nicely in this video by Dr. Steven Weiner, an expert in what he calls 'Sonoesthetics.'



And here is a demonstration of an ultrasound-guided botox injection into the masseter:




Sonoesthetics


Former ENT surgeon turned aesthetic physician Dr. Steven Weiner has become an expert in what he calls Sonoesthetics, or using ultrasound to map out the important vessels, inject filler and botox safely, as well as pinpoint complications that arise afterward. He uses a Clarius ultra high frequency probe to scan each patient prior to their injections, mapping out the depth and location of each major vessel in the face and recording this in the patient's chart for future reference. He gives a great lecture on it here:





In summary - like in other areas of medicine - POCUS adds certainty, safety, and precision. Can you do a paracentesis or arterial line without POCUS? Of course you can....until you can't. Anatomical variants are always going to be there. Why would you do it blind if you don't have to? The same is true with botox and fillers. Can you inject without ultrasound? Of course, but why would you want to when you can use POCUS and virtually eliminate the risk of blindness.




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