| InjeCTIon TeCHnIque | ARTicle The intradermal technique applied for the platysma to
redefine the facial contour is in two parallel rows, below the temporomandibular joint along the mandible towards the mandibular angle, perpendicular to the direction of the platysmal fibres. The medial row is approximately 1 cm from the lateral row, with the injection points between those of the lateral ones16
(Figure 4). For those with
submandibular fatty jawline, additional row(s) may be required under the mandible, depending on the width of the face. The dosage of onabotulinumtoxinA for the platysma of both sides is between 20–30 units (50–100 s.u). Additionally, the intradermal technique may be applied
to the lateral orbicularis oculi, in the lateral canthal area to soften the crow’s feet, to chase along the under-eye wrinkles, into the lines caused by repetitive frowning, and along the perioral lines; this uses approximately 40–50 u of onabotulinumtoxinA (100–150 s.u) for the entire facial treatment. The injection sites may be modified according to the extent of the wrinkles. Repeated treatment may be required in some areas for a more pleasing outcome.
Discussion Administering toxin for the entire treatment of the face is not as straightforward as injecting toxin in the isolated procedure. Injecting toxin to relax the frontalis is promising to reduce the forehead lines, while relaxing the platysma relieves the downward pull to redefine the facial contour. Relaxing both of these muscles rejuvenates the face but alters its shape. Without the pulling up and pulling down strength, the face appears somewhat rounder or fuller (Figures 5a and 5b). The facial configuration, balance and harmony are features considered as attractive. oval and heart-shaped faces, with sculpted cheekbones and fashionable hollow jowls are the classic ideal of any pleasant look, as illustrated by the concept of a phi mask or divine proportion. The key to achieve this goal is to consider not only the muscle function, but also its tone.
For the intradermal injection technique, toxin is injected
more superficially into the dermis to target the superficial part of the muscle inserting on the skin. Indeed, the muscle contracts from the insertion towards its origin; the intradermal injection technique is capable of relieving the muscle contraction while allowing the deeper part to function. Additionally, partially treated muscle initiates an increased resting tone in the remainder of the muscle17–18
.
Figure 5 Before treatment (A). Intramuscular injection to the frontalis and platysma rejuvenates the face with fuller configuration (B), compared to slightly oblong facial configuration created with the intradermal technique (C)
As a result, the intradermal injection technique minimises wrinkling, while preserving both muscle function and tone. The procedure is suitable for broad, flat, sheet-like muscles, rather than small muscle strands in which the injection sites should be precise. This technique is appropriate for flaccid muscle and lax skin, in which the relaxing injection may produce an unfavourable outcome. Furthermore, it is suited for those who like to keep a natural expression, without a frozen look. It may be applied to soften lines caused by repetitive muscle movement. Injection can be performed very early in the ageing process to prevent and smooth out the lines that remain at facial repose. In addition, it benefits those with submandibular fatty jawlines. When this technique is applied to the frontalis, it minimises forehead lines but preserves the ‘pull up’ strength. While the technique applied to the platysma relieves the downward pull, it still retains some muscle function and tone to ‘pull down’. These powerful muscles still possess their pulling up and pulling down strength to be able to stretch the facial muscle sheet to create facial rejuvenation with the tightening result; it softens the forehead lines, and redefines the facial contour with a smooth oblong facial configuration (Figures 5c and 6). The intradermal injection technique, sometimes
referred to as microinjection technique, applied to the platysma muscle in combination with masseter reduction treatment, further serves to shape and define the jawline and allows the platysma to hug the undersurface of the neck, making it youthful and tight19
.
prime-journal.com | October 2011
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