Dermal fillers improve volume loss or enhance facial features. Their use is increasing at rate of 10% or more per year worldwide. Adverse events are usually minor and consist of bruising, swelling, asymmetries, and nodularity. More significant complications are fortunately rare and include infection, granuloma, skin necrosis, and blindness. This blog will concentrate on techniques to minimize the risks of having a vascular event.
There are 2 ways a blood vessel can become occluded. If an artery is entered and filler is injected within the lumen (Intraluminal), filler will travel down the vessel until it gets lodged. At this point, the filler stops the flow of blood to areas which are dependant on this blood supply. Smaller pieces of the filler can break off and flow into areas far from the initial injection and into the very small arterioles. There are theories that an inflammatory response/cascade exacerbates the injury to the skin and dependent structures. This is Dr. Weiner’s opinion for the etiology of the majority of vascular occlusion cases.
A second way a vessel can occlude is if there is external compression of the vessel by filler. This is plausible in areas of compartmentalization, such as in the nasal tip. If the pressure within the nasal tip exceeds the pressure within an artery, flow will stop. Unfortunately in this area, vascularity is so poor that peripheral flow doesn’t occur. External compression is not a major problem in most areas of the face in Dr. Weiner’s opinion. Most vessels can be ligated during surgery and there is no resultant skin necrosis – proving that peripheral flow can make up for an externally compressed vessel.
The worst cases of vascular occlusion result in blindness. This is the result of a filler embolus that travels through an anastomosis between the external and internal carotid systems. The filler backs up into the central retinal artery which feeds the retina. Blood flow is blocked to the retina and blindness ensues.
In most cases, early recognition of a vascular event can be reversed with hyaluronidase if a hyaluronic acid filler was used. Minimal or no sequelae are seen if action is taken within the first 4-6 hours. Unfortunately, even immediate action for blindness related to a filler complication, has little or no success.
There have been about 100 reported cases of blindness from fillers, with most of the cases coming out of Asia. This is certainly underreported though. The areas of most risk for blindness are injections in: glabella, nose, periocular, and NLF. Fat is the most common filler causing blindness, but all fillers have been implicated. Any area of face is at risk for vascular occlusion/necrosis.
The key to avoiding vascular complications from fillers is implementing safe techniques and knowledge of the vascular anatomy. While there is a paucity of data to support this, Dr. Weiner believes that cannula injections are less risky than needles for a vascular event. Larger cannulas, 25g or larger, are less likely to enter a vessel than a needle. While there have been cases of vascular occlusion with cannulas, to the author’s knowledge, none have been reported with 23g or larger. The smaller the cannula, the closer it becomes to looking like a needle, and therefore the advantages are less. (Please read Dr. Weiner’s blog about cannulas to understand their advantages.)
Techniques for optimizing safety during dermal filler administration:
- Know the major vascular structures and their landmarks
- Avoid areas you (the injector) are not comfortable with. Particularly the high risk areas: glabella, nose, periocular
- Consider using only reversible fillers if there is any concern regarding vascular occlusion or experience
- Use cannulas whenever feasible, preferably 25/23g or larger
- Avoid boluses, small linear threads are safer
- Constantly move tip of cannula/needle. If more filler is needed in a particular area, revisit the area with another pass.
- A NEGATIVE ASPIRATION DOESN’T EQUATE TO BEING EXTRAVASCULAR AND CAN GIVE A FALSE SENSE OF SAFETY
- Injection onto periosteum is safest but does not guarantee a vascular free injection
- Pressure on the supratrochlear vessels during glabellar or nasal injections might limit reflux of filler into the orbital vessels
- Retrograde injections are safer than anterograde injections
- Dermal injections should be relatively safe
- Avoid deep injections in the lips. Stay superficial to the muscles
- An injection that is perpendicular to a vessel is purported to be safer than one which is parallel because the time within the vessel should be less if it is entered
- Have on hand 6-8 vials of Hylenex
- Any unusual bruising, pain or visual change needs immediate evaluation
The bottom line is that complications can occur with dermal fillers, even during a routine procedure. Many measures can be taken to minimize the risks. Choosing an experienced injector will result in safer and better outcomes.
Dr. Steven F. Weiner is the #1 physician trainer for Galderma (Restylane, Silk, Lyft, Sculptra, Defyne, Refyne). He has been using cannulas since 2011 and is one of the most experience injectors in the US.
Source: Dr. Steve Weiner, Facial Plastic Surgeon Blog