Permanent neuropraxia and brow ptosis after cannula temple filler
Dr Tim Pearce recently came across a case of a patient who suffered permanent brow ptosis or eyebrow drop because of dermal filler treatment to revolumise the temple administered using a blunt cannula. The patient immediately suffered brow asymmetry after the procedure that was expected to improve with time, but instead persisted. Several months later, the patient still lacks movement on one side.
In this blog, Dr Tim Pearce reviews what can happen when using a cannula for dermal filler revolumisation in the temple, exploring the nerve anatomy, and how to avoid the occurrence of a neuropraxia complication.
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The anatomy of the temple region: the facial nerve
Let’s start with the anatomy of the frontal branch of the facial nerve. This nerve emerges from underneath the zygoma and passes through the masseter muscle, coming up through and on top of the fascia of the muscle. It then makes its way up into the temple.
In making its way into the temple, the nerve elevates through the tissue layers, eventually passing into the zone where many aesthetic clinicians place a cannula when revolumising the temple with dermal filler. For this reason, it is quite commonplace to initiate some adverse effect on the nerve, however, this is usually only temporary.
Neuropraxia by Frotox
By contrast, the facial nerve can be injured on purpose. Several years ago, there was a treatment referred to as ‘Frotox’ that used cryo-neuromodulation with focused cold nitrous oxide to cool the nerves and freeze or numb an area, causing a neuropraxia for long enough to restrict contraction of the frontalis muscle, for example, to improve lines and wrinkles temporarily, in the same way as botulinum toxin.
Neuropraxia by Lidocaine
There is no need to panic if you perform the cannula technique with filler in temples, reassures Dr Tim. You will be relieved to find that, in most cases, if it results in brow heaviness, this is both quite common and temporary as an effect of the lidocaine within the dermal filler.
The space between the deep and superficial fascia, where the nerve resides, is exactly where the lidocaine is spreading out, thus affecting the nerve. This occurs in a large proportion of such treatments, and patients must be warned beforehand to avoid unnecessary anxiety and concern.
Most often, the effect will wear off in a matter of hours as the lidocaine anaesthesia wears off, in some cases taking up to 8 hours to fully resolve. Lidocaine blocks the sodium channels on the nerves meaning the impulse does not get through; as soon as the lidocaine disperses, activity returns to the muscle.
However, Dr Tim has encountered cases where something else has happened that is causing a much longer effect on the patient.
Neuropraxia by nerve trauma
Another type of neuropraxia is caused when a cannula damages the nerve. If you are unlucky with placement and it results in prodding, pulling, or compression of a nerve, you can temporarily stop it from working. According to Dr Tim, this is probably the most common type of nerve injury that you see after dermal fillers, particularly when delivered by cannula.
This type of injury is often the same as that experienced if you spend too long in a particular seated or resting position causing compression of the nerve in your leg, for example, resulting in a ‘dead leg’ progressing to ‘pins and needles’ upon movement. The same thing can happen with nerves in the face where a compression affects function, temporarily decreasing nerve activity, known as neuropraxia.
A key consideration is how long it took for the weakness to occur. If the muscle weakness occurred immediately during the procedure, rather than a few minutes or hours afterwards, it is more likely to be because of a more severe injury to the nerve. Thinking of the general action of neuropraxia, we know that it takes some time, with prolonged compression of the nerve before there is an outcome. Therefore, a compressed nerve is less adverse than a severed nerve, and a severed nerve would result in a more immediate change in the muscle activity in the area. However, continuous compression can also cause long-lasting neuropraxia.
In summary, the different types of temporary neuropraxia following dermal filler treatment can be commonly caused by lidocaine or compression, for example from post-procedural swelling, but the rarest type is because of a complete severing of the nerve which has a permanent neuropraxic outcome.
Techniques for injecting the temporal region
Dr Tim comments that he has noticed an anecdotal increase in complications from temple treatment. In the absence of published studies, it is difficult to ascertain if this is a random observation or a consequence of increased numbers of practitioners performing such procedures. Similarly, is there any link between the two different techniques often used in this area?
For example, some schools of thought believe that The Gunshot technique proposed by Dr Arthur Swift is particularly dangerous and they favour a cannula technique. Conversely, others feel the same level of nervousness at the thought of using a cannula.
In Dr Tim’s experience, both in clinical practice and during training at Skinviva Clinic and Skinviva Training Academy, where both techniques are employed, he has seen three different complications caused by cannula use. One compression of the vein in the area that caused swelling and protruding veins, resulting in the reversal of the dermal filler procedure, and two vascular occlusions to the superficial temporal artery.
He notes that he has yet to see any complications from injecting using the so-called Gunshot technique, but caveats that his sample size is not large enough for definitive evidence.
However, Dr Tim is keen to gather more data from the experiences of others as a learning opportunity. So, if you have seen complications from either temporal injection technique, do get in touch. You can find Dr Tim Pearce on Instagram.
What could cause long-lasting neuropraxia and facial weakness following temple filler with a cannula?
When using a cannula for dermal filler treatments, you cover a much larger area with your instrument than you do with a needle, by contrast, when using the gunshot technique in the temples.
Therefore, when moving a large instrument in and out of that tissue layer, you are much more likely to encounter and engage with a nerve, to poke or prod it, or potentially if you are relatively rough, you could even tear or break it. Damaging the nerve in this way causes a more severe injury classified as axonotmesis that can take months or years to improve but is most likely to be a permanent injury for the patient if the nerve is severed.
We often believe that using cannulas is safer for dermal filler treatment due to their ability to avoid penetrating blood vessels which could cause vascular occlusion, but they may not be appropriate for all areas of the face, especially if used relatively roughly which can injure tiny nerves in some areas, warns Dr Tim.
To avoid harm if you intend to use a cannula for temple filler treatments, he recommends small, slow, smooth movements. If you encounter any resistance, you should stop and attempt to find an alternative, easier path through the tissue. The gentler the better. Once you have opened the area by depositing a little of the filler product, the cannula will slide more easily without putting any pressure on additional structures.
Read up on other complications associated with dermal filler treatment at the temples, including temple lift complication: dermal filler-induced hair loss and understanding complications: scalp necrosis and temporal lifting.
Aesthetics Mastery Show
PERMANENT brow ptosis from a cannula?! Temple filler safety tips & cannula advice
Dr Tim says:
“I recently came across a patient who suffered from a permanent brow drop as a result of temple filler with a cannula. This patient immediately suffered brow asymmetry after the procedure that we thought would improve with time, but instead just persisted. So, how could this happen? In this episode I discuss why this has happened, the anatomy of the area, and how you can avoid this happening to your patients.”
Watch the full Aesthetics Mastery Show here.
The video has received feedback from subscribers and viewers on the YouTube channel, including the following comments:
“You are the best plastic surgeon professor”
“Thank you dr tim as always, eye-opening”
Read more comments and join in the debate on our YouTube channel.
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