Nasal Assessment Technique

By Mr Ayad Harb / 20 Aug 2019

Mr Ayad Harb shares his preferred assessment technique, the ‘squidge’ factor, when treating the nose with dermal filler

When assessing a patient for non-surgical rhinoplasty (NSR), one has to be mindful of the anatomical layers that make up the nose and take into account several factors. These include overall facial balance, the particular cosmetic imperfections in the nose, skin quality, patient psychology and one vital factor, which is difficult to quantify and can only be assessed by laying an experienced hand on the patient’s nose – what I describe to my patients, as the ‘squidge’ factor. In this article, I will explain what the ‘squidge’ factor is and explore why I believe it to be a suitable tool for patient education and nasal assessment. Though not scientific terminology, it is easily understood by all and clearly conveys the main limitations of treatment to the patient. Counselling using clear and unambiguous language, ensuring patient understanding, realistic expectations and informed consent, are vital in NSR treatment. Note that I believe NSR is a treatment that should be performed by experienced practitioners only.

Anatomical layers in the nose

There are four distinct layers that occupy the area between the skin and the underlying osseocartilaginous frame; the superficial areolar/fatty layer, the fibromuscular layer, the deep areolar/fatty layer, and the perichondrium/ligamentous layer, shown in Figure 1.1 Immediately under the skin, there are superficial fatty layers containing vertical fibers and septi running from the skin to the underlying SMAS. This layer is significantly thicker in the radix area and becomes extremely thin in the mid-vault region, while thickening in the supratip area.1 The SMAS of the nose is the continuation of the SMAS of the upper half of the face. The third layer of the nose is the deep fatty layer that separates the fibromuscular layer from the underlying nasal frame. The major superficial blood vessels and motor nerves run within this layer. A distinct feature of the deep fat layer is that it does not have fibrous septa, so injection into this layer is relatively easy and the resulting volume is smooth. However, the presence of major blood vessels makes this a high-risk area. The fourth soft tissue layer is the periosteum and perichondrium.2-4 Injection of filler is always aiming to be on this layer.

Figure 1: The anatomical layers of the nose

Facial assessment

For a successful NSR outcome, there should be a perfect harmony between the nose and the surrounding facial structures. Therefore, the first step in achieving a proper congruity between the nose and the rest of the face is familiarity with the entire face. The analysis of the face should take place in an organised manner by dividing it into three segments – upper, mid, and lower zones – and reviewing each zone on front and profile views. It is vital to remember that in the context of nonsurgical augmentation, manipulation of one structure may exaggerate the other disharmony in another. For example, in a patient with a relatively large nose and small chin, augmentation of the nose, albeit into a more aesthetically pleasing shape, may exaggerate the discrepancy and imbalance in the lower face and chin. In the upper face, one should observe the length and width of the forehead and the position and arch of the eyebrows. In the mid-face, the standard intercanthal distance is approximately 31-33mm. In the lower face, ideally the length of the nose should match the distance from the stomion to below the chin.5 Vertical alignment of the chin, lip and nose is examined carefully.

Skin quality

Skin thickness varies between patients and within different locations in the same nose.6 Patients who have either thick or thin skin may present to be a challenge in NSR. Patients with thick, oily skin often present difficulty in achieving acute definition due to the relative firmness of the thick dermis. On the other hand, thin skin introduces a higher risk of vascular injury and there are difficulties in hiding and moulding a highly cohesive gel implant.6 This information should be noted and discussed with the patient. One of my fundamental principles in NSR procedures is to minimise the amount of product used, in order to avoid dispersion and expansion of the product and subsequent widening of the nose or loss of the fine architecture and contour. It follows, therefore, that using a highly cohesive product that will produce more ‘lift’ per unit volume and that can withstand the weight of the overlying tissues, will mean that less volume is required and a superior result can be achieved.

Examination of the nose

Figure 2: Example of assessing a patient from above

One should adopt a systematic approach to nose assessment, focusing on the three essential points of the nose – the radix, dorsum and tip and examine their actual versus ideal shapes. Each of the three points should be viewed from the front, side and above. I find that assessing the patient from above reveals even the most subtle deviations and discrepancies, shown in Figure 2. I examine size, width, symmetry, deviation and projection, with a light source pointed up from the feet of the patient, to exaggerate any natural shadows and deficiencies. On the profile view, the first zone to assess is the radix, which should be 6mm deep for a female and 4mm deep for a male. The deepest portion of the radix is approximately at the level of the upper eyelash margin.5 The dorsal hump is assessed regarding its size and location. The nasal length is then assessed, which should equalthe distance from the stomion to the submental. There should be a well-defined supratip break for females, and less so in males.5 The columellar-labial angles should be around 94-97° for a male and 97-100° for a female. The columellar should protrude about 3-4mm caudal to the alar rim, as long as the alar rim is deemed to be in an optimal position.5

The ‘squidge’ factor

While it might be easy to imagine what a nose side profile might look like with certain injection strategies, it is vital to be able to advise the patient accurately and present them with realistic expectations and maintain a safety margin in all treatments. One of the most important factors that will determine the limitations, success or risks of a NSR is how flexible and ‘squidgy’ the tissues are. This is particularly true at the tip of the nose, where the size, stiffness and projection of the lower lateral cartilage, as well as the tightness and thickness of the overlying skin can have a major impact on the injector’s ability to affect any change in the shape and definition of the tip. I often ask the patients themselves to feel their nose or that of their accompanying partner or family member, comparing the ‘squidginess’ of the skin at the tip versus the radix. This enables the patient to realise the differences between individual noses as well as the different areas within the same nose, and hence the variability in the possible corrections and longevity of the results. An injector who has performed many NSRs will develop an ability to judge how much of a correction can be expected, based on palpation and pinching of the skin. This is certainly a skill that I have developed over the years and it has helped me to become more realistic and accurate when counselling my patients about their expected results. When assessing the tip of the nose, I perform a pinch test with the most distal parts of my index finger and thumb tips, and not the pulp area, shown in Figure 3. This generally allows me to raise a pinch of skin away from the underlying cartilage, even in the most challenging cases, to be able to assess the potential space between the two layers, where I could inject the dermal filler. Attempting to do the same using the pulps of the fingers generally raises the whole tip, including skin and cartilage and would not provide an accurate assessment.

In my experience, when considering NSR, the ideal nose should be adequately flexible, with around 2mm of skin pinch and a strong cartilaginous base provided by the lower lateral cartilages. This allows the practitioner to palpate the correct injection plane and create a space into which the filler is then easily injected.

Figure 3: An example of the ‘squidge’ factor

The overlying skin accommodates the new volume without tension, and the cartilaginous base withstands the additional weight and is able to provide the necessary support. These factors combine to produce a beautifully defined and well-projected tip. Typically, slim Caucasian and Asian noses exhibit this quality, making them ideal patients for non-surgical treatment. Heavy, sebaceous skin in men usually exhibits a tighter pinch test. Similarly, thick skin, particularly in patients of Afro-Caribbean or East Asian descent (where the tip contains a thicker subcutaneous fat layer) is usually less flexible, has a weaker cartilage and a tighter pinch test, which is more difficult to discern skin from underlying cartilage.7

Post-surgical patients can have a very tight skin pinch test, to the extent that sometimes there is absolutely no pinch possible, due to tight scarring from surgery and disruption of the natural anatomical planes. These patients should be approached with caution or avoided altogether if any concern lingers in the practitioner’s mind.

A tip that is overly tight, with very little or no skin-pinch or one where the cartilage is rigid, tenting the skin tautly and offering no flexibility, is a poor candidate for non-surgical correction and the risks of vascular compromise from intravascular injection or excessive pressure, are expected to be high.8 This is mainly due to the fact that the anatomical planes can become less well defined, making injection into the correct deep plane, more difficult and less predictable.

On the other hand, a tip which is excessively soft and flexible, whereby the entire tip feels as if it is ‘empty’, with palpable skin laxity and very weak cartilage support, is also a poor candidate for non-surgical correction. The problems arise from a skin envelope, which is lacking any structure or native volume and a thin and weak cartilaginous foundation. The skin laxity can lead the injector into a false supposition that re-inflation of the entire tip with filler is an imperative. However, this will commonly lead to a bulbous and overfilled tip that lacks any definition or projection. It is my belief that high volume injections raise the risk of vascular compromise, and these should be avoided at all times, particularly in the tip. Furthermore, the already feeble cartilaginous support will not stand up against the weight of additional filler gel and is likely to buckle, further compounding the existing problems of lack of definition and tip projection. The solution in this scenario is to target the caudal tip of midline septum with a small bolus of filler gel to improve tip projection. The most important point in this scenario is to temper the patient’s expectations, advising them that a slight lift is possible, however, a pointed, defined and raised tip is likely to be impossible and a high-risk target.

Conclusion

In order to achieve any enhancement at a given point, in particular the tip, adequate laxity of the skin is required. This can be assessed by a pinch test using the index finger and thumb tips. In cases of tightness of the skin envelope, where no skin pinch is possible, then the correct plane of injection is likely to prove challenging to access, exposing the injector to increased risks of incorrect placement, vascular injury or injection under higher pressure. In these circumstances, treatment should be avoided, and the patient should be counselled about the likely risks. Where the skin is felt to be very squidgy, similar risks may exist.

References
  1. Ozturk C, Larson J et al., The SMAS and Fat Compartments of the Nose: An Anatomical Study, Aesthetic Plastic Surgery, 2013.
  2. Oneal RM, Izenberg PH, Schlesinger J, Surgical anatomy of the nose, Aesthetic Plastic Surgery Rhinoplasty, 1993
  3. Firmin F, Discussion: the superficial musculoaponeurotic system of the nose, Plastic and Reconstructive Surgery, 1988.
  4. Letourneau A, Daniel RK, Superficial musculoaponeurotic system of the nose, Plastic and Reconstructive Surgery, 1988.
  5. Guyuron B, Precision rhinoplasty Part I: The role of life-size photographs and soft tissue cephalometric analysis, Plastic and Reconstructive Surgery, 1988.
  6. Lessard M, Daniel RK, Surgical anatomy of septorhinoplasty, Archives of Otolaryngology, 1985
  7. Chopra K, Calva D, Sosin M, A Comprehensive Examination of Topographic Thickness of Skin in the Human Face, Aesthetic Surgery Journal, 2015, Vol 35(8) 1007–1013
  8. Tansatit T, Moon H J, Rungsawang C, Safe Planes for Injection Rhinoplasty: A Histological Analysis of Midline Longitudinal Sections of the Asian Nose, Aesthetic Plastic Surgery, 2016

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