| BOTulInumTOxIn A | articLe
whereby the height change in the nasal tip elevation and projection can be predicted in patients treated with onabotulinumtoxinA (17). When a horizontal upper lip midphiltral crease is
accentuated with smiling, with or without a downward rotation of the nasal tip, an additional 1–3 u can be placed into each levator labii superior alaeque nasi. Injecting the depressor septi nasi and the lateral (labial) fibres of the levator labii superoris alaeque nasi can not only diminish the transverse line of the upper lip, but can also provide an apparent increase in the vertical distance between the columella and vermillion border, occasionally creating a fuller, more voluminous upper lip for some patients, but otherwise, adversely elongates a thin upper lip and vermillion in others (18).
Complications Higher doses of injected onabotulinumtoxinA produce a relaxation of the decussating fibres of the alar nasalis and depressor septi nasi, which can result in an unattractive, exaggerated widening of the nostrils along with the projection and elevation of the nasal tip. This forced widening of the nostrils can be accompanied by persistent pain and soreness over the nasal tip that can last for over 2 weeks (17). Weakening only the depressor septi nasi may just
elevate the nasal tip. However, if the onabotulinumtoxinA diffuses laterally from the midpoint of the base of the nasal columella and into the central upper lip levators, then the upper lip can become elongated and thinned, obliterating the contour and depth of the philtrum. Asymmetry and alterations in functional buccal sphincteric control may also result, producing difficulty with eating, swallowing and speaking. unless there is an obvious downward displacement of the anterior aspect of the nose and nasal tip when a patient forcibly lowers his/her upper lip, puckers, speaks, or smiles, injections of the depressor septi nasi should not be attempted.
Nasolabial folds Ageing, and a downward shift of soft tissue in the mid-cheek area, can deepen a nasolabial sulcus, which, in turn, augments its fold. The nasolabial fold is enhanced by the overall diminution of structural skeletal and muscular support, and intensified by the effects of ageing and the pull of gravity. The redistribution of facial soft tissue and fat is augmented with time and leads to the development of a vertical groove and fold that extend from the alar facial sulcus to the lateral labial commissures (18). Deep, diagonal folds from the sides of the nose that progress downward toward the angle of the mouth are a characteristic sign of advanced age. These deep furrows and folds remain the more difficult and barely correctable harbingers of senescence. In the past, surgical procedures have attempted to efface the outline and depth of the groove, but are fraught with scars and failure. Injections of soft tissue fillers have achieved some success, and are probably the best technique for elevating and softening these lines. OnabotulinumtoxinA has been used in an attempt to reduce the appearance of nasolabial folds, but
Figure 7 The different morphological types of nasolabial folds. (A) Convex,, (B) Straight, and (C) Concave. Source: adapted from (20)
has also proved fraught with complications in this area.
Functional anatomy There is significant variation in the anatomy that creates the nasolabial fold, which extends from a point lateral to the nasal ala to a point lateral to or lower than the oral commissure. In older patients, a combination of any of the following may also contribute to a prominent nasolabial fold: ■ loss of skin thickness over the sulcus ■ Redundant skin lateral to the sulcus ■ Excessive fat deposits lateral to the sulcus that are fixed in place by retaining ligaments ■ Ptosis of the malar and submalar fat laterally as a result of a weakening of the superficial muscular aponeurotic system (SmAS) in the mid-upper cheek. Ageing and frequent mimetic action of the causative
facial muscles can deepen the vertical sulcus that runs from the upper border of the nasofacial angle downward and laterally toward the commissures of the mouth. nasolabial folds can appear convex (60%), straight
(30%), or concave (10%) (Figure 7). With regard to an individual’s idiosyncratic facial morphology, the nasolabial fold can be divided into three sections: the upper or medial, middle, and lateral or lower section (19). According to some, it is the levator labii superioris
alaeque nasi that is the muscle most responsible for producing the upper medial portion of the nasolabial fold and the levator labii superioris for deepening the middle of the nasolabial fold (3,4,19–21). In most individuals the zygomaticus major and levator anguli oris help to elevate the corner of the mouth and move it laterally and slightly upward with smiling. In so doing, they can mobilise the mid-cheek skin upward and laterally, extending the lower crow’s feet down the face, especially in those who have inelastic, loose, redundant skin. Both muscles of the zygomaticus complex (major and minor) can deepen the nasolabial fold when they contract.
Dosing Inject 1u (no more than 2u) of onabotulinumtoxinA into the middle of the nasofacial angle, just lateral to the upper border of the ala nasi. While sitting or in the semireclined position, ask the patient to snarl or lift the upper lip forcibly in an upward direction as one does when sneering or expressing abhorrence. With the index finger of the non-dominant hand directly over the nasofacial angle and palpating the area gently, one will feel the contracture of muscle fibres as the patient repeats the sneer manoeuvre. With the needle
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