6 Deep Danger Points in Facial Filler: Anatomy You Must Know Before You Inject

Every part of the face has a legitimate reason to inject, with indications running from the earlobe to the forehead, and the constant judgement an injector makes is between the aesthetic result they want to achieve and the places where reaching for that result carries a particularly dangerous complication risk. There is no part of the face you might not want to augment for one reason or another, and there are several places where you would hold off injecting even though you can see exactly what you would like to change, because the anatomy underneath does not forgive a misplaced needle. This is the first in a three-part series on facial danger zones, covering the six deep danger points where knowing precisely how to find the structure is what allows you to avoid injuring it.

The thread running through all six of these areas is depth, because nearly every one of them becomes dangerous specifically when a needle is placed deep onto the periosteum where the vessel runs. The recurring principle is to chip away at the risk with everything anatomy gives you, palpating for the landmark, staying superficial where the fat protects you, reaching for a cannula where trauma needs to be reduced, and weighing the size of the potential injury against the benefit before deciding to treat it at all.

The supratrochlear and supraorbital arteries on the forehead

Working from the top of the face down, the first two vessels to respect are the supratrochlear and supraorbital arteries, which supply the forehead and come off the orbital blood supply. That orbital connection is what makes them so dangerous, because they share a blood supply with the retina, and this is the number one area for causing blindness in aesthetic practice. The reassuring side is that you can often locate them precisely, feeling the supratrochlear notch medially and the supraorbital foramen laterally, with the bony shape palpable and a pulse sometimes detectable in slim or nervous patients.

A periosteal injection around the orbital rim is one of the worst techniques you could employ in this area, and a deep needle here is an absolute no. The total risk of blindness remains very small at around a one in a million event, and the working philosophy is to understand the anatomy and chip away at that risk to see how low it can go. Pointing the needle away from the orbit so the filler flows in the opposite direction, compressing the vessel with a finger during injection so product cannot track into the orbit, using a product you know aspirates, and most importantly injecting superficially at a level well away from the periosteum, all stack together to reduce the danger.

A deep frown line that makes a patient look permanently cross genuinely affects how they communicate with other people, which is often a good reason to take a carefully managed risk in this area. Hundreds of these treatments performed with good technique and small amounts of filler at a time have produced no occlusions, with the chance of blindness under those conditions being very small. Each injector is in charge of their own risk tolerance, and anyone uncomfortable with this area should simply not treat it.

Forehead and glabella augmentation

The primary indication around the glabella is a crease, but the entire area can be augmented, with filler under the brow used to masculinise a face by creating a heavier brow ridge, and some patients seeking a more dominant forehead to differentiate the orbit. Large-volume forehead projection using six, seven, or eight mils at a time is a rare procedure in the UK but happens around the world, and it relies primarily on a cannula with a great deal of attention to how gently it is handled, the angle of entry, and checking the mobility of the cannula tip before injecting.

Aspiration works with cannulas, which Dr Amy at SkinViva proved through a series of experiments after the initial assumption had been that it probably would not work. Product viscosity determines whether aspiration is possible at all, with a thick product defeating aspiration and a low viscosity product allowing it, which is one more way of protecting the patient even though nothing guarantees complete safety.

The infraorbital foramen

Sitting just medial to the midpupillary line, the infraorbital foramen is a palpable area that usually feels more tender because the nerve emerges alongside the artery. This is a branch of the maxillary artery, and occluding it can block much of the midface blood supply along with the supply to the hard and soft palate and the nasopharynx, which makes it a genuinely nasty place to cause an occlusion. A deep injection here is an absolute no, and while the nearby nerve means a patient would usually react and remind you, you would never rely on that instead of knowing your anatomy.

The biggest protection is to mark out the area and stay away from it, because there is very little reason to go there when most revolumising happens above, lateral to, or inferior to the foramen. An occlusion of this artery has been seen where an injector treating the nasolabial fold angled slightly upward and caught a branch of the infraorbital artery. Staying superficial is the key protection, because most people have plenty of fat above the foramen, and being up in that fat rather than deep on the bone is a relatively safe place to be. The foramen is deep enough that you can feel the indentation on your own skull, so you should know when you are above it.

The mental foramen

The mental foramen sits on the chin, emerging parallel with the infraorbital artery, and can often be felt though it is a little harder to locate. Going wrong here mostly produces a superficial occlusion of the skin and the mentalis muscle, but the vessel is a branch of the inferior alveolar artery, so a high enough volume can affect the blood supply to the teeth and the floor of the mouth, which covers the whole lower third of the jaw. The distinction is that superficial occlusion of the external branches affects the skin, while filler injected so it flows all the way back through the mandible reaches a much larger and nastier territory.

Chin volumising is the main reason to be in this area, replacing the fat pad rather than defining the region, and the foramen sits about a centimetre lateral to the marionette line for most treatments. The protections are knowing your anatomy, palpating for the foramen, putting small amounts in at a time while gauging the patient’s response, and using a cannula for reduced trauma. As with every artery on this list, the central rule is to avoid deep injection onto the periosteum, with the nearby nerve offering some warning if you go too deep, though that is never something to depend on.

The facial artery at the antegonial notch

Moving laterally, the entry of the facial artery into the face at the antegonial notch is a very dangerous place to put a needle, with the pulse palpable in slim patients or after exercise. Injectors quite often place needles on the periosteum a few centimetres lateral to this point, and there is footage of untrained operators running boluses all the way along the jaw and luckily missing it, but blocking this vessel compromises the blood supply to that entire side of the face.

The way to avoid it is to stop doing boluses along the jaw, to palpate and understand the shape of the bone, and to use landmarks. The gonial angle itself, the actual angle of the jaw, is a fairly safe place to know you are clear of the artery, and getting the patient to bite down lets you feel the masseter, with the artery sitting just anterior to it. A needle is never placed at that depth at that point, and as you move down the mandible you reach the zone where the artery is likely to be hit. Where volume genuinely needs adding, the approach is to cross the area gently with a wide-bore cannula big enough that it cannot easily penetrate a vessel, nudging respectfully through the fat well above the level of the bone.

The deep temporal vessels

The deep temporal vessels run on the periosteum behind the zygoma and supply the temporalis muscle, and they are quite different from the superficial temporal artery. They sit exactly where an injector revolumising the temple onto the periosteum was traditionally taught to work, with the older training treating the temple as dead easy and simply bolusing it without much focus on aspiration. The deep vessels connect with the maxillary artery, so occluding them blocks that important supply to most of the midface.

The blindness cases associated with the temple appear more likely to involve the superficial temporal artery, because of its anastomoses with the supraorbital artery, with the reviewed cases all involving low viscosity products that fit the picture of floating through those connections. The chance of the deep temporal artery connecting to the retina is incredibly low, with only a theoretical route through an accessory meningeal artery in some people. The greater concern with the deep vessels is the midface supply they feed.

The severity of any temple occlusion is amplified by the bolus technique, because injecting half a mil in one spot means that if the whole half a mil enters a vessel the result is catastrophic. Occlusions are weighed in terms of frequency and severity, with the infrequent but very severe events being the ones that cause the most worry, since big occlusions affecting internal structures are extremely hard to reverse. The bullet hole technique applies a significant amount relatively high and lateral at a point often called the Swift point, named after Arthur Swift, where filler can be placed more safely because it sits superior and more medial than the deep temple vessels.

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