How To Prevent Nerve Damage While Using Injectable Fillers?

In different non-surgical facial procedures, fillers are used to inject in the dermis and mid-dermis skin layers. Out of these fillers, some are semi permanent while others are temporary fillers. As these fillers are not injected into deeper skin layer where nerves are located, so aesthetician think that there is not going to be any potential harm.

However, the important thing to understand in this regard is that it is not necessary that the fillers directly cause harm to the nerves, the injury can be also be caused due to some indirect cause. If any complication or infection develops at an early treatment stage, it can spread in the surroundings affecting the underlying nerves. Even in some cases, the late complications like granulomas or late skin infections can also involve the underlying nerves.

The procedure of injecting fillers

The key to injecting fillers is injecting the right filler at the appropriate level to the right patient and also at appropriate time.

Steps involved in injecting fillers

• Proper sepsis removal: This should be the first step of fillers administration. It has been observed that some of the practitioners treat the patients without properly cleaning the area with alcohol wipes or without preparing the area before injecting fillers. This can be dangerous practice and proper sepsis removal should be done prior to the treatment.
• Giving proper analgesia: this should be the second step. For this purpose either topical anaesthetic cream or dental block can be used.
• Providing comfortable settings to the patient: also ensure to provide comfortable settings to the patient so that patient feels at ease. This is the key to injecting at accurate point because any movement during injection might lead to nerve damage.
• Precise pre-operative markings: this is also a crucial step. By doing precise markings the danger zones, which should be avoided during the treatment, are identified.
• Considering the filler injection technique: once the filler to be used is decided, the next step is to choose the injection technique for the fillers.

Understanding the facial nerves

Many different studies had been performed regarding the facial nerves which only provide bi-dimensional guidelines to the practitioners. But for treating with precision three dimensional nerve understanding was required which has now been achieved through the redefinition of the various nerve layers, especially located in the temporal area.

• Brief overview of different layers

For better understanding, here is a brief overview of various layers. First is the skin, then some subcutaneous tissue layer followed by SMAS or galea cells and then the superficial temporal fascia. There are also some loose tissues that separate the SMAS and the periosteum layer and are of significant importance.

Developing understanding about the various layers from the perspective of superficial temporal fascia is essential while injecting on the zygomatic arch because it helps in identifying the specific fat pad during the dissection for facelift.

Seven facial danger zones to avoid while injecting fillers

There are seven facial nerves danger zones which should be avoided while injecting fillers to the face.

1. Area behind the ear: the great articular nerves supply this area. But this area behind the ear is of not much concern because it is not particularly treated.
2. Area on the cheek: temporal branch of facial nerve supply to this area which expands all across the zygomatic arch. Particular attention should be paid to this area while doing cheek or zygomatic arch augmentation because the injection is injected into the deep dermis and the layer of zygomatic arch is very thin. If proper care is not taken while injecting fillers, potential harm can be caused to the frontal temporal part of the facial nerve. The injury would affect the forehead area causing the eye ptosis.
3. Area supplied by mandibular or marginal branch: It is a deep area lying under the mass. The location of this area is easy to identify. It’s a circular area with a possible radius of 1.5-2cm lying between oral commissure and the mid-mandible.When the branch of manidbular, moves towards the pre-jowl lines, it makes the anterior of chin extra superficial, innervating the depressor labii inferioris muscle and the depressor angularis oris muscle. In some cases, this area is considered to be common for injecting fillers. So when the filler injection is placed medially in this region, the terminal of facial nerves branches tends to become extra superficial that could lead to an injury.
4. The triangular area formed by eminence of malar, the oral commissure and the posterior border of the mandibular angle: the cheeks and the nasolabial folds are possibly the most commonly injected area for fillers.
   Zygomatic and buccal branches of the facial nerve provide supply to this area which is not considered very sensitive branch. At the terminal branches, lots of nerves are located but if infection or granuloma occurs then evidently nerves are there which can lead to devastating consequences. It would affect the area above the upper lip, cheek and the nose.The zygomatic major and minor are spread all across this particular area, so this area should be marked cautiously while performing fillers treatment.
5. Area located above the Superior Orbital Rim above the mid-pupil line: it is mainly the area of Botox treatment that is supplied with the supraorbital and supratrochlear nerve. Fillers are usually not injected into this area. The injury signals can be the feelings of numbness in forehead, nasal, upper eyelid, dorsum and anterior scalp.
6. Area lying inferior to the orbital rim underneath the mid-pupillary line: this zone is located 1cm inferiorly to the orbital rim below the mid-pupillary line.In this region, infra-orbital nerve is located so extra care should be taken while injecting local anaesthesia or dental block as it may harm the nerves causing numbness in the upper cheek, nose and upper lip and chronic long term pain to the infra-orbital nerve.This landmark is very important- just 1 cm below the infra-orbital rim having a radius of 1.5 cm. All this area is supplied with the infra-orbital nerve.
7. The mental nerve: this nerve can be easily identified as it is located in the mid-mandible just underneath the second premolar. Again, care should be taken while injecting dental block or anaesthetic in this area to numb the lower lip, so that no harm should be caused to the mental nerve.

The injections of fillers in the pre-jowl region are increasingly becoming popular and practitioners should take into consideration that these nerves tend to become more fragile and superficial while leaving from the foramen. All this area is supplied by the nerves so it could lead to the severe complications, if injected wrongly.