Keywords
lips - contouring - volumizing - labial arteries - danger zone
Lips are the central point of focus in the lower face and have always played a key
role in facial attractiveness. Besides their function as a perioral sphincter (together
with the perioral muscular complex), lips are majorly involved in the expression of
emotions, speech building, and food intake. The human lips have evolved during various
evolutionary steps when compared with the lips of apes: they have increased in volume
and the vermillion became more everted.[1] The eversion of the lips is thought to increase the contrast between the white/brown
perioral skin, and the increased volume is thought to facilitate nonverbal communication
and thus increase attractiveness.[1]
In today's society, these features, contrasting pigment color and lip fullness, are
still considered to increase facial attractiveness and have become a major area of
interest. Using lipstick increases the contrast between the lips and the perioral
skin, whereas using soft-tissue fillers increases the lip volume. The demand for the
latter (soft-tissue filler volumization) is increasing independent of gender, ethnic
background, or age. Hyaluronic acid-based soft-tissue fillers are one of the most
used agents for this type of treatment.[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
On the contrary, loss of lip contour, lip volume, and/or presence of perioral wrinkles
are considered signs of facial aging and have been associated with reduced attractiveness.[12]
[13] Reducing the signs of lip aging is crucial to restore facial attractiveness. Multiple
techniques to restore facial aging via the treatment of the lips have been described.[14]
[15]
[16]
[17]
[18]
[19] However, few of these techniques have been validated for the positioning of the
injected product in relation to the superior/inferior labial arteries. It is widely
accepted that injection of soft-tissue filler material into the arterial system is
associated with tissue loss (necrosis) and potential end-arterial embolism (potential
blindness).[20]
[21]
[22]
[23]
The present study describes and summarizes injection techniques targeting the lips
with hyaluronic acid-based soft-tissue fillers, which are frequently used in Middle
Eastern and Caucasian patients. The injection techniques included in this anatomical
study are based on the experience of the authors, each with more than 20 years of
experience treating signs of facial aging and the lips using soft-tissue fillers.
The included injection techniques were verified in the cadaveric model for their positioning
within the upper/lower lip in relation to the superior/inferior labial arteries.
Material and Methods
Injection Techniques
The injection techniques presented in this study are based on the experience and personal
selection of the authors. The authors have assessed, treated, and evaluated for more
than 20 years patients from the Middle East and Central Europe. Based on individual
algorithms of the authors, some of the most frequently used injection techniques are
presented in the following.
The injection techniques presented include the usage of a 27G x 1/2” and 30G x 1”
sharp needle (various companies) and 22G x 2” and 25G x 1 ½” blunt tip cannula (various
companies). Various injection points were used and each technique was tailored in
application and amount of injected product based on patients' needs and clinical indication.
Anatomical Verification
The same injection techniques as used by the authors in the (living) patients were
performed in the upper and in the lower lips of three fresh cadaveric specimens (1x
male / 2x females) having a mean age of 84.67 ± 10.02 years and a body mass index
of 26.18 ± 5.45 kg/m2. Specimens were screened and not included into this analysis if previous facial surgery
or diseases disrupted the integrity of the facial anatomy. Each body donor had given
informed consent while alive for the use of his or her body for medical, scientific,
and educational purposes. All aspects of the study conform to the laws of the country
where the study was conducted.
The injected product (for the cadaveric injections) was commercially available hair
gel mixed with commercially available food coloring to visualize the injected product
inside the cadaveric tissue. The superior and inferior labial arteries were previously
injected with red latex, to visualize the arterial vascular system of the lips. Cross-sectional
dissections and photo-imaging was performed to identify the placement of the injected
colored product inside the lips and to relate the position of the product to the superior/inferior
labial arteries.
Discussion
This study presented 12 different injection techniques frequently used in Middle Eastern
and Central European patients when addressing the lips for aesthetic purposes. The
presented techniques included contouring (using a needle), volumizing (using both
needles and cannulas), and labiomental treatment (using both needles and cannulas)
for labiomental volume loss. Cadaveric verification was performed for each of the
presented techniques to identify the positioning of the injected product inside the
superior/inferior lip. The results of the anatomic analyses revealed that in 58.3%
of the performed injections the product was placed in close proximity to the superior/inferior
labial arteries. The placement of the injected material in the vicinity of the superior/inferior
labial arteries indicates a high risk for intra-arterial applications, leading to
tissue loss (necrosis) and potential end-arterial embolism (potential blindness).
In 60.0% of the cases, applications using a needle placed the injected product in
endangered locations, whereas 57.1% of the cases using cannulas placed the product
in endangered locations (i.e., in the vicinity of the superior/inferior labial arteries).
The results of the anatomical analyses, however, need to be interpreted with caution.
First, positioning the product in close proximity to an artery does not necessary
mean that the product was placed inside that respective vessel. Placing any product
inside the lips requires skills and experience. The location where a product can be
injected is limited to the reduced thickness of the lips, which holds especially true
for aged lips and those needing treatment. Thus, it can be assumed the any product
injected has a certain relationship to the labial vasculature, but the precise plane
and the used injector will influence the outcome. However, being in the same plane
as the artery (submucosal, intramuscular, or subcutaneous) represents a higher risk
to potentially penetrate intra-arterially, whereas having the product separated by
the orbicularis oris muscle represents a certain degree of safety.
Second, the vasculature of the lips is highly variable. A recent study has reported
that three different positions of the labial arteries are possible: submucosal (i.e.,
between the oral mucosa and the orbicularis oris muscle in 78.1% of the cases), intramuscular
(i.e., between the superficial and deep layers of the orbicularis oris muscle in 17.5%
of the cases), and subcutaneous (i.e., between the skin and the orbicularis oris muscle
in 2.1% of the cases). The variability in changing the respective position along the
labial course was 29% for the total upper and 32% for the total lower lip.[24] The present study confirms the results presented in this report as the labial arteries
were identified to run in variable positions independent of the upper/lower lip. On
the contrary, the presence of multiple labial arteries also indicates that lips are
very forgiving in their nature due to their excellent vascularization. Adverse vascular
events might be tolerated and masked well before being clinically apparent. This might
be one of the reasons why this few adverse vascular events are being reported in relation
to the magnitude of performed labial injections for aesthetic purposes.[22]
[25]
[26] It can be stated that injections deep inside the lips, that is, intramuscular or
submucosal, for volumizing procedures (independent if conducted with a needle or a
cannula), are associated with a higher risk for intra-arterial positioning of the
product.
Third, in the present study the lumen of the arteries was filled with latex, which
does not allow a needle or a cannula to penetrate inside the vessel. In a clinical
scenario, some of the performed injections in this experimental setting might have
positioned the material inside the artery. This is represented in the current analysis
by a close relationship between product and artery and could be potentially considered
as an indicator for a higher risk for an intra-arterial injection.
The injection techniques presented in this study are based on the experience and personal
selection of the authors. The authors have assessed, treated, and evaluated for more
than 20 years patients from the Middle East and Central Europe when targeting lip
contour, lip volume, and labiomental volume loss. Albeit the focus of a specific treatment
might be the lips, which can be sometime expressed very directly by the consulting
patient, it has to be well explained that the perioral region needs to be addressed
first and later the lips themselves. Lip treatment is a multistep approach. Perioral
volume loss, perioral wrinkles, and even midfacial or upper facial corrections should
be assessed first (if agreed by the patient). Perioral treatment options can influence
significantly the positioning of the lips (cranial repositioning after addressing
the nasolabial sulcus) and the volume of the lips (increased eversion after treating
the deep midfacial fat compartments due to influence of the levator labii superioris
alaeque nasi muscle). Age-related changes in the perioral region are caused by a combination
of several factors including changes in bony structures (loss of alveolar process),
loss of subcutaneous volume (fatty deflation theory), skin laxity (loss of collagen
and elastic fibers), and skin sagging (gravity induced). These changes can cause ptosis
of the oral commissures, resulting in an inferiorly positioned and deflated labiomental
region. The formation of a prominent labiomandibular sulcus (i.e., the marionette
lines) can likewise influence the appearance of the lips due to the close relationship
to the corners of the mouth.
Middle Eastern females have in general good labial volume, whereas Central European
females in the same age group have slightly less volume. Thus, the treatment should
focus here rather on contouring than on volumizing. Applying volume in the white (skin
covered) and red lips forms a subcutaneous scaffold that stabilizes the lips and provides
support for the lower third of the face. Based on the cadaveric part of the present
study, it should be noted that 58.3% of the volumizing procedures were related to
a potential intra-arterial injection because the product was injected deep inside
the body of the lips. On the contrary, procedures aiming for contouring can be regarded
as safer as in this case, the product was positioned in the subcutaneous plane which
is separated from the arteries by the orbicularis oris muscle.
Conclusion
Based on the experience of the authors, the treatment of the lips should be a multistep
approach focusing first on the far (upper and middle face) and close (labiomandibular
and labiomental) perioral regions. Individuals with an acceptable lip volume should
be directed more toward the treatment of the lip contours, whereas individuals with
volume deficiency should have first the volume and secondary the contours addressed.
The lips are a potential danger zone as 58.3% of the performed cadaveric injections
were in close proximity to the superior/inferior labial artery (and its branches),
representing an elevated risk for tissue loss (necrosis) and potential end-arterial
embolism (potential blindness).
