The role of ultrasound in aesthetics injections of botulinum toxin and dermal fillers: part 2
Updated: Jan 14
The use of ultrasound guided dermal filler injections
Hyaluronic acid fillers are the most commonly used dermal filler products with over 2.4 million treatments performed in the United States in 2016 (Schelke et al 2018). Classed as a minimally invasive procedure hyaluronic acid filler treatments have become popular for the treatment of fine lines and wrinkles by replacing the loss of soft tissue volume caused by fat pad atrophy in the face (Descates 2021). Complications of
are rare but can be termed
mild, moderate or severe and include allergy, local erythema and swelling, palpable nodules, hyperpigmentation (Wortsman and Wortsman 2011), as well as vascular compromise, tissue necrosis and blindness (Sito 2019) from vascular compression or intravascular injection (Schelke et al 2018, Descates 2021). Reports of complications have increased over the last decade with the growth of the nonsurgical cosmetic procedure industry as most cosmetic injections are performed without ultrasound guidance (Mehta et al 2022, Wortsman and Wortsman 2011). The use of ultrasound in aesthetics practice can have a number of advantages: 1) pre injection mapping of important facial anatomy and vasculature to avoid complications – this requires Doppler ultrasound which helps to detect directional movement such as blood in vessels (Kaproth-Joslin et al 2015) , 2) the identification of previous filler type used where applicable, and 3) identify the location of filler and treatment directly with hyaluronidase in the case of complication (Schelke et al 2018).
Pre scan mapping of important facial anatomy and vasculature
Serious adverse reactions to filler injections have been previously described in this paper. Knowledge of facial vascular anatomy prior to injection is desirable however it is not clinically visible (Schelke et al 2018). Using safe injection techniques taught on training courses such as using cannulas in moderate to high-risk areas, aspirating and injecting slowly (Iwayama 2018) may reduce the risk of adverse events. However, there is variability in individual facial anatomy (Kim et al 2021) and pre-injection ultrasound scanning can help to identify vascular structures to be avoided (Schelke et al 2018).
A common area treated with hyaluronic acid filler is the nasolabial fold. There is risk of injection into or vascular compromise to the facial and angular artery in this area. A retrospective case series study of 50 patients by Lee et al (2021) aimed to visualise the arterial anatomy of the nasolabial fold using Doppler ultrasound prior to cannula injection of filler and to investigate whether Doppler ultrasound insured safe filler procedure. The ultrasound examination demonstrated that in about one third of cases the facial artery was detected lateral to the nasolabial fold with the remaining cases showing the facial artery beneath the nasolabial fold. The artery was also detected in different layers of the subcutaneous tissues. The study demonstrated that after ultrasound guided hyaluronic acid injections no patient experienced severe vascular complication and only mild to moderate adverse events such as bruising were reported. This has also been highlighted by Iwayama (2018) in a case study where the same subject had each nasolabial fold injected with hyaluronic acid, one side using a cannula under ultrasound guidance and the other side using a conventional injection technique. No adverse reactions were reported but interestingly skin blood flow was maintained more effectively after using the US guided procedure than with the conventional method.
Injection of filler into the supratrochlear artery and thus the internal carotid artery increases the risk of blindness and injection of filler into the glabella is a high-risk procedure. Lee et al (2021) investigated the use of Doppler ultrasound to determine the relationship between glabella wrinkles and the supratrochlear artery pathway and the safety of filler injections in this area. 42 subjects were enrolled into this study and injected with hyaluronic acid under ultrasound guidance. In 59% of subjects the supratrochlear artery was lateral to the glabella wrinkle line and in the remaining subjects the artery was located under the glabella line. As in the previous nasolabial fold study discussed by Lee et al (2021) there were no severe vascular complications with only mild adverse events such as bruising reported. The authors concluded that the use of ultrasound prior to glabella dermal filler injection to confirm the location of the supratrochlear artery and avoid vascular complication is recommended.
These studies highlight the usefulness of using Doppler ultrasound to increase the safety of filler injections in high-risk areas to prevent vascular compromise and adverse events. The evidence that is evolving remains of low level with small sample sizes and no control groups or randomisation of injection technique. Future research that addresses these methodological issues will add to the evidence base.