The role of ultrasound in aesthetics injections of botulinum toxin and dermal fillers: part 3
Effective management of complications
Mlosek et al (2020) in a study of subjects with palpable nodules following dermal filler injection report hyaluronic acid deposits visible on ultrasound as well-defined round or oval, anechoic lesions and fibrosis as a large hyperechoic region of different size within normal tissues with posterior acoustic shadowing. However, they found it more difficult to evaluate granulomas based on ultrasound criteria. Identifying the cause of a nodule may better inform a practitioner dealing with an adverse reaction on the correct choice of management.
Jaguś et al (2021) in a retrospective study of 12 subjects have described the use of Doppler ultrasound for the diagnosis of vascular compromise following hyaluronic acid filler injections, highlighting symptomatic subjects with vascular compromise. Colour Doppler detects directional flow within blood vessels and can highlight to the user the course vessels travel through the tissue planes (Kaproth-Joslin et al 2015). Most machines depict arterial flow as red and venous flow as blue on colour Doppler. Hyaluronic acid is hydrophilic so appears anechoic or hypoechoic on ultrasound and depending on the technique used; multiple small hypoechoic deposits can be seen if a cannula was used or a large hypoechoic area if a bolus was delivered via needle injection (Schelke 2018). The case studies presented by Jaguś et al (2021) nicely depict the hypoechoic fillers in close proximity to the brightly coloured blood vessels which can help to highlight vascular compromise.
In the case of an adverse event US guidance can be used as part of the treatment protocol. Hyaluronic acid fillers can be dissolved using hyaluronidase so adverse events can be clinically managed if identified early enough (Schelke et al 2018). Hyaluronidase can be delivered directly into the hyaluronic acid deposit under US guidance adjacent to vascular structures relieving the vascular compression.
Identification of previous filles types
All fillers including hyaluronic acid are visible on ultrasound (Schelke et al 2018). Dermal fillers can broadly be classified as temporary or permanent (Lei et al 2019). Temporary fillers include hyaluronic acid, calcium hydroxyapatite, poly L lactic acid (PLLA) and polycaprolactone (PCL). Permanent fillers include polyacrylamide and liquid injectable silicone (Lei et al 2019).
A retrospective study of 60 subjects by Urdiales-Gálvez et al (2021) aimed to determine if dermal fillers are recognisable on ultrasound and the ultrasound patterns corresponding to different dermal fillers. In this cohort studied most of the subjects were unaware of the filler they had been injected with previously but were verbally informed the filler was natural and resorbable. Based on their small sample size the authors define four ultrasound patterns corresponding to the echotexture on ultrasound, attributing this to a particular type of filler injected and highlight how this allows clinicians to identify the nature and behaviour of the different injected fillers over time. Schelke et al (2018) outline the importance of identifying previous fillers used prior to administering further filer injections as combining different products could lead to unwonted side-effects such as inflammatory reactions. As with many studies in the field of ultrasound and aesthetic injections Urdiales-Gálvez et al (2021) acknowledge study limitations such as a small sample size, and heterogeneity of the technology used and the expert individual interpretation of their findings.
This paper has highlighted that ultrasound and the use of colour Doppler is becoming more widely used in the practice of aesthetic injections. Protocols for ultrasound scanning and mapping of facial anatomy have been reported as has the use of ultrasound for guiding botulinum toxin injections for aesthetic procedures, however this practice is perhaps mostly unnecessary. However, colour Doppler ultrasound use has been shown to be very useful for safely guiding dermal filler injections to prevent vascular compromise and serious adverse events. With the development of ultrasound technology improving and the costs of machines become more affordable there should be wider use of this technology and more training courses established to allow practitioners to up-skill in the field of aesthetic procedures under ultrasound guidance. It is the intention of the author, already competent in musculoskeletal ultrasound, to develop facial ultrasound skills and incorporate them into clinical practice to increase safety and reduce the likelihood of adverse reaction and complications.