| boTulInuM ToxIn A | ARticle Similar lip fullness and eversion can be realised when
botulinum toxin is injected in a less painful way a few millimetres above the vermillion line. To maximise the augmentation and eversion of the lips without inflicting additional pain, place the needle into the cutaneous lip 2 mm superior to the vermillion border and advance the tip of the needle until it reaches the pars marginalis just under the vermillion. This manoeuvre is facilitated by standing behind the patient, grasping, and with moderate pressure, compressing the lip between the index finger and thumb of the non‑dominant hand. The slight discomfort experienced when the lip is compressed between the fingers will distract the patient from feeling the full impact of pain when the lips are injected.
Complications The perioral area is probably the most difficult location on the face to treat without the occurrence of adverse sequelae. This is because, unlike the sphincteric action of the orbicularis oculi, which has only one opposing levator (i.e. frontalis) and a few brow co‑depressor muscles, the orbicularis oris is interlaced with muscle fibres from different groups of upper and lower lip levators and depressors, making it easy for the injected botulinum toxin A to diffuse into an adjacent muscle or muscle group. In the case of overdosing, many different adverse
functional changes can occur, which can include the inability to form certain letters, to articulate different sounds, and to pronounce certain words. Involuntary biting of the tongue, inner cheek, and lip may result, along with flattening of the philtrum, or even lip paresthesias. There can also be a concomitant inability to approximate the lips tightly enough to prevent fluid or even food incontinence8–10
.
The inability to purse or pucker the lips can last beyond 2–4 weeks after treatment. one should not be tempted to inject progressively higher doses into the lips similar to the way one can increase the injection dose in the periorbital area. Doing so will definitely lead to any number of adverse sequelae. It is important to understand that there is only a very narrow margin for the successful treatment of the orbicularis oris with botulinum toxin A. If 2 u per quadrant is injected into a patient’s lips, effectively and without untoward sequelae, then as little as an additional 1–2 u of onabotulinumtoxinA in the upper or lower lip in that same individual may result in unwanted adverse side‑effects. Avoid injecting too close to the corners of the mouth; this can result in incompetent commissures, eclabium, an asymmetric smile, aberration in speech, drooling, and even food incontinence. of all the areas on the face to inject botulinum toxin A, the lips are the most painful. The more superficial the injection, the more painful it will be, but the better the results.
Asymmetric smile Many people are born with an asymmetric smile. This can be a manifestation of a family trait (Figure 2), which is especially disconcerting to women who display this type of smile. for many, this is a source of considerable embarrassment, especially when they are in social situations. like those with a gummy smile, they are reticent
to grin in public, and seek ways in which to hide their mouths when laughing or smiling in the presence of others.
Functional anatomy no matter what type of smile one has 11
, if it is asymmetrical
or ‘crooked’ it is always a source of anxiety and self‑consciousness for the bearer12
. Asymmetric smiles
can occur because of segmentally weakened or hyperfunctioning muscles on either side of the upper or lower lips. If the asymmetry appears in the upper lip, one or more of the upper lip tractors or a segmental portion of the orbicularis oris may be involved. If the asymmetry appears in the lower lip, a unilateral malfunctioning of a lower lip tractor occurs that is often weaker or stronger than its contralateral muscle. lower lip asymmetries are more easily corrected because the problem commonly stems from a hyperkinetic depressor labii inferioris, or occasionally a depressor anguli oris13
. The depressor labii inferioris is a quadrilateral muscle
that originates inferior to the mental foramen at the oblique line of the lower lateral surface of the body of the mandible between the symphysis menti and the mental foramen. As one of the direct labial tractors, its fibres travel upward and medially to insert directly into the skin and mucosa of the lower lip, decussating with fibres of its paired muscle from the opposite side along with some muscle fibres of the lower orbicularis oris. Its function is to pull the lower lip downward and laterally, slightly everting the vermillion when a person chews, drinks, smiles, laughs, or speaks. It should act in unison and symmetrically with its paired counterpart on the opposite side of the chin, which is not always the case in some individuals.
Dosing ordinarily, the unilateral stronger muscle of the face is weakened with injections of botulinum toxin A to correct an asymmetry. Depending on the type of asymmetry to be corrected, and the location and strength of the muscle(s) to be weakened, it is advisable for the injector to determine the appropriate dose. before treatment, the patient should be in the sitting or
semi‑reclined position while forcibly contracting the muscle to be treated. Commonly, it is the depressor labii inferioris that is hyperkinetic and creating an asymmetric smile. As the patient smiles energetically, the location of the hyperkinetic muscle is easily visualised. The needle should pass perpendicular to the skin’s surface and enter directly into the belly of the muscle. This injection point is usually inferior to the mental crease and the inferior limit of the orbicularis oris. Generally, 2–4 u of onabotulinumtoxin A will weaken the hyperfunctional depressor labii inferioris sufficiently to realign an asymmetric smile (Figure 3)12
.
Outcomes once the problem has been assessed, and the correct dose determined, weakening the hyperkinetic muscle on the side of the face producing the asymmetry with injections of botulinum toxin A will correct the asymmetry (Figure 3). The effect of a single treatment can last 5–6 months, if not
prime-journal.com | July 2011
Treatment implications when injecting perioral rhytides
by botulinum toxin A treatments.
1 Only dynamic wrinkles
superficial fibres of the orbicularis oris will relax surface rhytides, evert the vermillion, and create the appearance of fullness.
2Treating hyperkinetic
symmetrically placed injections in all four quadrants of the pars peripheralis. Each injection site can be dosed differently with the tip of the needle
3Treat the lips with
advanced to just beneath the vermillion.
4Inject the lower lip
conservatively and with a slightly lower dose than in the upper lip to avoid functional aberrations.
5Avoid injecting close
to the corners of the mouth, for risk of creating incompetent
commissures, eclabium, an asymmetric smile, and drooling.
in the lips are reducible
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