TY - JOUR
AU - Papadopoulos, Tim
AB - Normal means “within the normal range of variation” —Keith L Moore, (Canadian anatomist, 1925-2019) The authors of this prospective study enrolled volunteers to determine normal lip anatomy not affected by age-related changes.1 Ultrasound imaging was performed at 3 different locations on the upper and lower lips, respectively, to determine the position, the depth, the cranio-caudal location of the superior (SLA) and inferior labial arteries (ILA) within the lips in relation to the vermilion border, and lastly their diameter. The purpose of the study was to provide clinically relevant information on the 3-dimensional (3D) pathway of the SLA and ILA arteries within the lips to improve safety during lip augmentation. Included were 41 healthy volunteers (gender balanced) with a mean age of 26.17 ± 9.6 years and a mean body mass index (BMI) of 23.09 ± 2.3 kg/m2. These volunteers were thoroughly screened and had no previous perioral fillers or neuromodulators, facial surgeries or trauma, or any type of disease that would affect the anatomical integrity of the face. The authors were able to demonstrate that the most frequent location of both the SLA and ILA was the submucosal plane (58.5%) followed by intramuscular (36.2%) and subcutaneous (5.3%) planes. The depth of the SLA in the upper lip was 5.6 ± 0.13 mm, whereas the depth of the ILA in the lower lip was 5.2 ± 0.14 mm. Both arteries were more frequently located within the red lip (vs cutaneous lip): upper lip (83% vs 18.7%) and lower lip (86.2% vs 13.8%). In the midline, the artery coursed within the red lip in all volunteers. The conclusions of the study were that (1) an injection technique in the subcutaneous plane is preferable (ie, more superficial), and (2) a perpendicular approach to the lip might be safer because the artery courses horizontally most frequently within the red lip (ie, reduced contact area). This study is clinically relevant in view of the recent advances in both injectable fillers and radiological imaging. The conclusions reached are fairly straightforward, and the results of this study confirm the findings noted in previous cadaveric studies2,3 and another ultrasound-based investigation conducted in an Asian population.4 The merits of this study are firstly, that the data utilized were obtained from imaging studies of the living rather than cadavers (despite the cohort being a young population). Secondly, the authors discussed the spatial relationship of the labial arteries in relation to the vermilion border, demonstrating that the vessels resided in just over 80% of cases within the red lip (Figure 1A). Lastly, this study confirms the labial vessels likely change their anatomic relationships coursing proximally to distally, going from deep to superficial when reaching the midline (ie, sagittal plane) (Figure 2). However, we do know that this anatomy/topography is altered further with aging, jaw positioning, and the amount of tissue stretch of the lips on handling when injecting fillers (Figure 1B).5 Figure 1. Open in new tabDownload slide (A) Cross-section demonstrating the anatomy of the inferior labial artery in the central one-third of the lower lip of this 37-year-old female. Note that the inferior labial artery is found within a few millimeters of the surface of the lip posterior to the wet dry line, the most common location for this vessel in the central one-third of the lips. (B) Cross-section in an elderly cadaver demonstrates both muscular and fat atrophy, which–along with preservation with formalin and desiccation–can cause some further changes to the volume and delicate shape of the orbicularis oris muscle within the red lip. This may result in distortion of surface landmarks like the wet dry line and hence the relative position of the labial arteries. Figure 1. Open in new tabDownload slide (A) Cross-section demonstrating the anatomy of the inferior labial artery in the central one-third of the lower lip of this 37-year-old female. Note that the inferior labial artery is found within a few millimeters of the surface of the lip posterior to the wet dry line, the most common location for this vessel in the central one-third of the lips. (B) Cross-section in an elderly cadaver demonstrates both muscular and fat atrophy, which–along with preservation with formalin and desiccation–can cause some further changes to the volume and delicate shape of the orbicularis oris muscle within the red lip. This may result in distortion of surface landmarks like the wet dry line and hence the relative position of the labial arteries. Figure 2. Open in new tabDownload slide Schematic diagram demonstrating the most common planes in decreasing order transgressed by the labial arteries in the lips: submucosal, intramuscular, and subcutaneous. Preparation of anatomic specimens for numerous workshops and publications by the author also demonstrate a combination of the above. In approximately two-thirds of cases, the arteries will remain in the same plane, and in the remaining one-third, 50% will change 1 plane and 50% of 2 planes before reaching the midline.2 Note that this labial vascular anatomy is variable not only between individuals but also from side to side within the same individual. Figure 2. Open in new tabDownload slide Schematic diagram demonstrating the most common planes in decreasing order transgressed by the labial arteries in the lips: submucosal, intramuscular, and subcutaneous. Preparation of anatomic specimens for numerous workshops and publications by the author also demonstrate a combination of the above. In approximately two-thirds of cases, the arteries will remain in the same plane, and in the remaining one-third, 50% will change 1 plane and 50% of 2 planes before reaching the midline.2 Note that this labial vascular anatomy is variable not only between individuals but also from side to side within the same individual. To underscore the importance of lip vasculature, a recent anatomic study revealed that 58.3% of all lip injections performed demonstrated filler material located in proximity to the SLAs/ILAs, independent of the injector (and utilization of needle/cannula) and the injected plane (submucosal, intramuscular, subcutaneous).6 This indicates a potential “high risk” for vascular adverse events (VAE), including previously documented irreversible blindness.7,8 Unintended intra-arterial hyaluronic acid (HA) injection into all branches of the facial or ophthalmic artery has been reported, and no region of the face is completely safe. In addition, there is a paucity of information from anatomical studies about the facial artery branches to the chin, lips, and nose, which exhibit variable origins and courses (not only between individuals but also from side to side within an individual).9-12 The only thing we can do is assert some statistical probability regarding a vessel location, at best. Although the authors of this study listed facts and data regarding labial artery diameters and BMIs of their patients, they failed to discuss their significance in any detail. For example, the diameters for the SLA and ILA from lateral to midline were reported as 0.91-0.75 mm and 0.83-0.76 mm, respectively. That, of course, does not equate to the diameter of the lumen, which would be considerably smaller in size.3 But it is worth remembering that the tip of a 25-gauge is 0.5 mm in diameter and a 30-gauge needle is 0.3 mm, hence why some practitioners prefer to utilize a 22-gauge cannula to reduce VAEs. Patients with an increased BMI have thicker tissues as noted in the study. This would naturally imply that (1) the distance would be increased from the skin surface to the labial arteries, and (2) the labial arteries may be larger to supply the metabolic demands of the tissues. But what is more important and relevant to the practitioner is that when these individuals lose significant weight (>20 kg) and drop their BMIs back to or near normal, their arteries may remain the same (large) caliber as they were before weight loss. This is exactly what is seen in body contouring surgeries in massive weight loss patients.13 Therefore, massive weight loss patients may pose an increased high risk in lip augmentation procedures. In the scientific literature, one can find numerous attempts to answer the question of what is the safest method to inject fillers in the lips. Many of these techniques rely on certain beliefs, but no single approach has proven to be the gold standard. The authors of this study propose that an in-depth knowledge of the 3D course of the labial vessels, including their relation to the vermilion border, will “increase safety during labial soft tissue filler injections” and protect against accidental VAE. The takeaway message is that we know this is not the case. In reality, there is no safe way to inject the lips and despite a detailed knowledge of anatomy and injection technique, even the most experienced practitioners can have VAEs and poor aesthetic outcomes. Anatomists and experienced practitioners acknowledge that there are high-risk and low-risk zones, but never no-risk zones to inject in the face because anatomy at these small scales is both variable and unpredictable. So, there will always exist some risk for VAEs that we cannot eliminate. All we can say, however, is that a few anatomical and physiological truths exist regarding the lips and facial artery vasculature: The facial artery can terminate as the (A) ILA branch, (B) SLA branch, (C) lateral nasal artery ± alar branch, and (D) angular branch.14 The ratios vary in previous studies because most were limited to cadavers, whereas others employed various technologies (eg, ultrasound, conventional and CT angiography) and different classification systems. There are currently interesting modalities under investigation to visualize facial (and palmar) arteries in a non-invasive way, but unfortunately at present all lack the 3D depth required for safe injecting.15-17 Symmetry of the facial artery occurs between 52.7% and 68%.11,12,18-20 Symmetric facial arteries end as the angular branch in 50% and lateral nasal branch in 45.8%.11 Asymmetry of the facial artery shows commonly as the lateral nasal branch on one side and contralaterally as the SLA.11,14,19 Some branches of the infraorbital artery anastomose either with the angular branch of the facial artery or the dorsal nasal branch of the ophthalmic artery.21,22 Injury to the infraorbital artery may lead to compensated blood supply from the facial artery with opening of variable anastomotic sites leading to retrograde flow into the ophthalmic artery. A recent study shed some light on our understanding of how VAEs related to HA injections were associated with the anatomical distribution of choke (reduced-caliber) and true (without reduction of vessel caliber) anastomoses connecting the facial artery to the neighboring ophthalmic and maxillary angiosomes.23 Here the choke vessels define the boundary of necrosis of the involved artery, and true anastomoses allow free passage to a remote site. Although HA is well tolerated outside the vessel wall, it is highly inflammatory within blood vessels,24 but only the choke vessels have the capacity to respond with spasm, thereby restricting blood flow and dispersal of the HA filler into adjacent vascular angiosomes. Aging of the perioral area is a multifactorial process with unfurling and potential thinning of the lips. Whether in the young or old, thinning lips increase the risk of VAEs given the decreased distance from the surface of the lip to the artery. It may be worth considering a multimodal approach utilizing a combination of surgical shortening of the upper lip by a lip lift and the utilization of fillers for volumizing or contouring the lips. These work synergistically to produce a result that is more than the sum of the different parts.25 I would like to mention that you cannot really know anything if you only remember isolated facts like the ones stated above. If the facts do not coalesce in the form of principles, they are unusable. Principles are like a blueprint to draw your attention to the important elements of whatever you are facing or simply a representation of how something works. We utilize principles to retain knowledge and simplify how we understand things (ie, we cannot relearn everything every day), and so we construct principles to help us perceive patterns and navigate our world more efficiently. The following 3 principles (acronym ATM) have been beneficial for me when applied to lip augmentation utilizing filler injections: Anatomy: Inject superficially at the vermilion border or within the dry vermilion and no deeper than 3 mm.10,26,27 The upper lip ages with different degrees of tissue lengthening (sagging), thinning, and volume loss most pronounced in the sagittal plane.28 Avoid altogether or utilize extreme caution when injecting scarred/traumatic areas in the lip. Technique: Utilize local anesthetic (1% xylocaine with 1:100,000 adrenaline) at commissures 0.5 cc and infraorbital foramen region 1 cc, bilaterally, for both anesthesia and spasm of labial vessels. Utilize low-pressure injections in both antegrade/retrograde fashion, keeping the end of the needle/cannula tip moving. Inject utilizing small syringes (0.5-1 cc) and small needles (ie, 27 or 30 gauge) or cannulas (22 or 25 gauge) with magnification to help better visualize the plane of placement and flow of material. Note that small-caliber needles decrease the speed of injection and minimize overestimating the volume of injection, especially for smaller particle fillers. Medium: HA-based gels injected in small quantities are generally very satisfactory and can be easily reversed with hyaluronidase. Larger particle fillers are effective for volumizing or deep lines, whereas smaller particle fillers are more appropriate for perioral fine rhytids and the vermilion border.29 The anatomy of every single human being is unique. That statement by itself implies that there are as many anatomical variations as there are humans. The takeaway message is that we all need to exercise caution regardless of the location of the SLA/ILA because there are always variations. No matter how much anatomy we may know, we simply cannot eliminate all risk. We thank the authors of this study for both illuminating the 3D anatomy of the labial arteries in the young and suggesting that injecting fillers into lips in a superficial plane may manifest in less adverse outcomes. Acknowledgments The author thanks Dr Morris Ritz MD, FCS (SA), FRACS and Dr Tass Tasiopoulos BSc (Hons), MBBS, FCPCA for their kind review of this manuscript. Funding The author received no financial support for the research, authorship, and publication of this article. Disclosures The author declared no potential conflicts of interest with respect to the research, authorship, and publication of this article. REFERENCES 1. Cotofana S , Alfertshofer M, Schenck TL, et al. Anatomy of the superior and inferior labial arteries revised: an ultrasound investigation and implication for lip volumization . Aesthet Surg J . 2020 ; 40 ( 12 ): 1327 - 1335 . Google Scholar OpenURL Placeholder Text WorldCat 2. 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Facial fillers in lip reconstruction . Operative Techniques Otolaryngology-Head Neck Surg . 2020 ; 31 ( 1 ): 38 - 44 . Google Scholar Crossref Search ADS WorldCat © 2020 The Aesthetic Society. Reprints and permission: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - Commentary on: Anatomy of the Superior and Inferior Labial Arteries Revised: An Ultrasound Investigation and Implication for Lip Volumization
JF - Aesthetic Surgery Journal
DO - 10.1093/asj/sjaa248
DA - 2020-11-09
UR - https://www.deepdyve.com/lp/oxford-university-press/commentary-on-anatomy-of-the-superior-and-inferior-labial-arteries-1vXfDuyWXJ
SP - 1336
EP - 1340
VL - 40
IS - 12
DP - DeepDyve
ER -