Dr Ahmed El Houssieny offers guidance on using botulinum toxin A to address some key aesthetic nasal concerns
Non-surgical rhinoplasty (NSR) is an increasingly popular non-invasive option for men and women who wish to address the effects of ageing on the nose or to modify congenital characteristics.1,2 Not only does NSR save on cost and recovery time associated with surgery, but it also allows for subtle changes that are in keeping with today’s emphasis on achieving facial harmonisation.1,2
Although many are familiar with the use of dermal fillers to achieve NSR, botulinum toxin type A (BoNT-A) has been shown to be a safe and effective treatment option for several aesthetic nasal procedures.3-5 However, because the use of BoNT-A in the mid-face, including the nose, is off-label, it is of particular importance that the treating clinician has a detailed knowledge of both the muscles of the face and their action and interaction.
Injecting into the correct plane and limiting spread and diffusion of the toxin is, in my experience, crucial in the mid and lower face where muscles often interdigitate.6 Furthermore, the muscles in this area can be more sensitive to the effects of BoNT-A and lower doses are usually required.7 In this article, I outline some key procedures and offer my guidance to facilitate precise, safe and effective treatment of this central facial feature.
At the initial consultation, the clinician should assess patient expectations and be clear about what might be achieved. When selecting a treatment option, literature suggests that the approved type A toxins available are similar, although vary in terms of units, chemical properties, biological activities and weight and, hence, are not interchangeable.8,9
It is important to ensure that the patient has no contraindications to the use of the toxin (such as pregnancy or lactation)10 and to be aware of any medical conditions. Doses cited in this article are for onabotulinum toxin A (onaBTX-A). When reconstituting the toxin for nasal procedures, I recommend that 1ml of bacteriostatic saline is used to reconstitute a 100U vial of onaBTX-A in order to prevent unintentional diffusion of the toxin to adjacent muscles. Treatment intervals for these procedures should not be more frequent than every three months.7
Nasoglabellar lines, commonly referred to as ‘bunny lines’, are formed by the contraction of the transverse nasalis. The lines may be accentuated in people who habitually wrinkle the nose – those who wear heavy glasses or have chronic rhinitis, for example – or may simply be a result of ageing.11
The approach to treatment needs to be tailored according to the individual patient. Initial treatment is usually an injection of 2-5U in the transverse nasalis on either side of the nasal spine (Figure 1). This has been observed to result in satisfactory improvement of wrinkles in around 40% of patients, with 60% experiencing persistent nasoalar, nasociliary or naso-orbicular wrinkles.3 One approach to assessing persistent wrinkles is to monitor the pattern of any additional wrinkles over two weeks following the initial injection and treat accordingly with further injections of 2U in the requisite areas.3
It is important that the injections associated with treating nasoglabellar lines are administered medially and not laterally into treated muscles to limit diffusion. Diffusion in the lip levators, the levator labii superioris alaeque nasi (LLSAN) and the levator labii superioris, can result in asymmetry or upper lip ptosis, which may affect functions such as speaking and eating.6 Diffusion in the orbicularis oculi can affect lacrimal function.11 Injections that are too low and too deep into the nasal sidewalls can result in injection into the angular artery or vein or cause ecchymoses or haematoma.6 Needle placement should be intradermal or superficially subcutaneous in this area to minimise spread.6 Any patient requesting treatment of nasoglabellar lines alone should be considered for treatment of glabellar lines at the same time, according to published literature.12 Conversely, it is recommended that nasoglabellar lines should also be treated if glabellar line treatment is requested. This is to prevent compensatory contraction of either the transverse nasalis or the procerus, causing either horizontal lines at the nasal root or secondary nasoglabellar lines if only one area is treated.13 For treatment of the procerus, 3-5U are recommended.12 However, as discussed above, this is off-label and I believe that only experienced practitioners should treat the nasoglabellar lines.
Drooping of the nasal tip can be the result of ageing or of gravity, combined with the hyperkinetic action of the depressor septi nasi.13 In some individuals, movement of the nasal tip occurs naturally during speech. It should be noted that BoNT-A will not be effective in individuals with a genetic downward-pointing nasal tip that is not dynamic.6,13 Static causes such as nasal septum or cartilages require a different approach. Identifying the aetiology of the ptosis is, therefore, key to successful treatment. Asking the patient to give a forced smile can show if the tip is actively rotated.13
Another integral element to treatment is an assessment of the musculature of the individual patient. The depressor septi nasi is not the only muscle responsible for depressing the nasal tip.14 For example, interdigitation of fibres in the depressor septi nasi and the dilator naris means that, in a small number of individuals, smiling or the formation of certain sounds can lead to widening of the nasal aperture and rotation of the tip.13 In some patients, the dynamic action of the depressor septi nasi and LLSAN muscles can result in the upper lip being pulled upwards as the tip of the nose is pulled downwards, leading to a horizontal upper lip crease when the mouth is animated.6 This line can be treated by injecting 1-3U of BoNT-A into each LLSAN and depressor septi.6
In order to inject precisely into the depressor septi nasi, the patient should extend their upper lip downward, elongating the muscle and separating it from the orbicularis oris. The columellar can then be injected while the clinician holds it or pushes the tip of the nose with the non-injecting hand (Figure 1). Stronger muscles require higher doses, so it is important to assess the strength of each muscle by observing them during rest and movement, as well as through palpation.15 Stronger muscles can be indicated by deeper lines, greater movement and larger mass.15 The depressor septi nasi, for example, will be stronger in some patients than others.6,13 A typical dose ranges from 2-5U. Where there is interdigitation of fibres between the depressor septi nasi and the dilator naris, an additional injection into the ala on both sides of the nasal tip will be required to lift the tip. An additional 4-5U in the nasal ala dorsum is suggested.13 However, minimum amounts of BoNT-A should always be used to avoid diffusion into the lip levators, as discussed above.6
The voluntary or involuntary contraction of the dilator naris muscle can occur naturally or due to stress. The resulting opening of the nostrils is exaggerated, causing the columella and septum to be revealed.11,13 Small doses of BoNT-A can weaken the dilator nasi, producing an overall narrower nasal aperture that does not interfere with breathing in.6 Suitable patients for treatment with BoNT-A are those who can flare their nostrils at will.11 Individuals with a wide nasal bridge and alar base may have particularly well-developed dilator naris muscles as well as the medial alar portion of the LLSAN.6
Subcutaneous injection should be into the dilator naris at the alar rim of each ala nasi and should be given where contraction is greatest (Figure 1).6,13 This is usually at the mid-point. As with the other nasal procedures I have discussed, lateral injection should be avoided so to prevent diffusion into the lip levator muscles. Dosage recommendations range from 2-10U of onaBTX-A per side.7,13 No adverse effects have been noted with this treatment approach.6,11,13
Excessive perspiration of the bridge of the nose occurs more rarely than at sites such the axilla, palms and feet, but it is nonetheless a condition which may cause social embarrassment to the individual affected.4 It is thought to be more common in men than in women and to worsen with age.11 Patients who undergo treatment with BoNT-A report not only decreased levels of hyperhidrosis but also improved quality of life.16
BoNT-A inhibits the release of the neurotransmitter acetylcholine that stimulates the eccrine sweat glands.16 As injection is intradermal, it can be painful so pain relief is recommended.4 My preference is for a topical local anaesthetic. Injections are given over the affected area with a space of 1cm between each one.11 It is important that they are applied symmetrically. A case study of two patients experiencing nasal dorsum hyperhidrosis reports effective treatment and no adverse effects from administering a total of 20 injections of 0.1ml per unit to each patient, where a 100U vial of onaBTX-A was reconstituted with 10ml of normal saline.4
Due to the anatomical complexities of the mid-face, knowledge and observation of facial anatomy is crucial to achieving the safe and effective treatment of aesthetic nasal concerns using BoNT-A. Assessing the structure and action of the facial muscles in each patient enables the optimal choice of injection points and dose of toxin. Precise administration of the toxin using minimal volumes is of particular importance in achieving symmetry and avoiding motor disruption to the mouth and eyes. By applying experience, knowledge and careful judgement when treating the nasal area, the clinician is able to work with the patient to achieve the facial harmonisation that treatment with BoNT-A can offer.