articLe | BOTulInumTOxIn A | with onabotulinumtoxinA for a nasal flare.
Nasal tip ptosis With age, the nasal tip in some individuals naturally rotates downward, partly because of the pull of gravity and partly because of the pull of a hyperkinetic muscle of the nasal septum (i.e. depressor septi nasi). There are others who, because of idiosyncratic skeletal morphology, possess a downwardly rotated nasal tip since birth (Figure 4). In others the nasal tip will noticeably rotate downward in an up and down motion as they speak or pucker their lips. For those patients whose nasal tips actively move and rotate when depressing the upper lip or when speaking, onabotulinumtoxinA injections have provided a non-invasive means to elevate and project the nasal tip upward. For adynamic, static, inferiorly pointing nasal tips, only soft tissue fillers or surgical rhinoplasty can be corrective. Dynamic nasal tip ptosis can be accompanied by
excessive upper lip shortening and occasionally, the presence of a gummy smile and a transverse line across the upper lip and philtrum (14). This horizontal upper lip crease can be exaggerated in older patients with dermatochalasis and skin laxity. It is also found in younger patients when there is curling of a short upper lip with smiling (15). These patients will also typically exhibit an excessive amount of gingiva when smiling or laughing.
Functional anatomy The paired depressor septi nasi is often considered a component part of the dilator naris. It originates from the nasal spine at the centre of the incisor fossa of the maxilla deep to the orbicularis oris and on the medial cartilaginous crura (14). Its fibres course upward and insert into both the mobile cartilaginous nasal septum and the mucous membrane undersurface of the ala nasal. The depressor septi nasi pulls the nasal septum downward, draws the ala inferiorly, and narrows the nostril. In some individuals, the lip and alar insertions are
comingled with fibres of the levator labii superioris alaeque nasi. As a result of the variability in the anatomy and the multifactorial aetiology of nasal tip ptosis and dynamic nasal tip retraction, injections of onabotulinumtoxinA to elevate and project the tip of the nose is not as easy to perform as one might think.
Dosing To effectively treat a dropped nasal tip, have the patient depress his/her upper lip downward, widening the junction between the base of the nasal columella and the upper lip. This elongates the depressor septi nasi, separating it away from the orbicularis oris. This allows one to place the needle precisely into the depressor septi nasi at the base of the columella, and not into fibres of the orbicularis oris, before injecting onabotulinumtoxinA (Figure 5a). With the patient in the sitting or semireclined position,
grasp the columella between the thumb and index finger of the non-dominant hand at the same time the patient is
24 ❚ May 2011 |
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Figure 5 (A) Injection of the depressor septi nasi in the centre of the columella. (B) Injection of the depressor septi nasi at the base of the columella
forcing the upper lip downward and underneath their incisors and canines (Figure 5b). Another technique is to lift the tip of the nose superiorly and gently push it posteriorly with the thumb of the nondominant hand (Figures 5a). Depending on the strength of the depressor septi nasi,
2–4 u of onabotulinumtoxinA can be injected just superior (1–2 mm) to the labiocolumella boundary line (Figure 5a). An additional 2–4 u of onabotulinumtoxinA can also be injected into the middle of the columella and nasal tip, if the strength of the depressor septi nasi is visibly excessive and hyperfunctional (Figure 5b). Stronger muscles will require higher doses of onabotulinumtoxinA (16). In some patients whose depressor septi nasi also interdigitates with the dilator naris, an additional 2–6 u of onabotulinumtoxinA on both lateral aspects of the nasal tip will be necessary to effectively elevate and project the nasal tip.
Figure 6 (A) The nasal tip of the 26-year-old actively rotated downward with speaking, smiling, and laughing before 4U of onabotulinumtoxinA; 2U at the base and 2U in the centre of the columella. (B) Same patient 1 week after onabotulinumtoxin treatment
Outcomes Injecting onabotulinumtoxinA into the depressor septi nasi will relax the muscle, lifting and projecting the nasal tip upward. The combination of injecting both the columella and the alae just posterior and lateral to the nasal tip with onabotulinumtoxinA will relax the lower end and base of the nose, producing additional lifting of the nasal tip by the medial (alar) fibres of the levator labii superioris alaeque nasi (17). Results can last 3–4 months, and slightly longer with repeat treatments. If there is no movement of the nasal tip when the upper lip is depressed or while the patient smiles, speaks, puckers, or purses the lips, onabotulinumtoxinA injections should not be given. Atamoros devised a therapeutic dosing scheme
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