Ultrasonographic Analyses of the Forehead Region for Injectable Treatments

Singular entry point technique for forehead and temple filler augmentation: Anatomical and clinical perspectives

BACKGROUND

The depressed volume of the forehead and temple is resolved by filler injection. However, the current method has the potential to cause pain and side effects in patients, depending on the skill of the clinician. Therefore, this study proposes a new method for safer and simpler injection using only one injection entry point.

METHODS

Using the novel injection method, the filler was injected into the forehead and temple regions in three unembalmed cadavers and two healthy Korean volunteers. The cannula and filler locations were identified using dissection, ultrasonography, and three-dimensional (3D) scanning.

RESULTS

Ultrasonographic images and dissection results showed that the filler injected into the cadavers was in the target layer. The cannula and filler were located on the layer as the supraperiosteal layer on the forehead and the supra deep temporal fascia layer in the temple. Finally, 3D scanning images showed that the filler was injected precisely and effectively into the forehead and temples of the volunteer who underwent the procedure.

CONCLUSIONS

This method can reduce pain and minimize externally visible wounds caused by injections. The injected filler was naturally connected from the forehead to the temple and maintained for around 3 months. Additionally, it is possible to inject fillers into the forehead and temple at a constant and safe depth without requiring specific skills. It is expected that this method will become a universal method because it minimizes the burden on both patients and clinicians.

An Exploration of the Anatomy of the Forehead of Asians and Its Relationship With Forehead Lines Based on Ultrasound Imaging

BACKGROUND

A profound understanding of the various frontal tissues' morphology and their relationship with forehead lines can efficiently guide clinical treatment.

OBJECTIVES

The authors explored the relationship between frontal anatomy and frontal lines.

METHODS

We measured the thickness and shape of tissues in different regions of the forehead of 241 Asians. Then, we analyzed the relationship between the types of frontalis muscle and frontal lines, as well as the relationship between the frontal anatomical structures and the production of frontal lines.

RESULTS

We classified the types of frontalis muscle into 3 categories comprising 10 subtypes. The skin (0.78 mm vs 0.90 mm, P < .05), superficial subcutaneous tissue (0.66 mm vs 0.75 mm, P < .05), and frontalis muscle thickness (0.29 mm vs 0.37 mm, P < .05) of people with obvious dynamic forehead lines were significantly thicker than those of people without significant dynamic forehead lines. However, no significant difference in the deep subcutaneous tissue thickness was found between people with and without static forehead lines (1.36 mm vs 1.34 mm, P < .05).

CONCLUSIONS

This study shows the relationship between the frontal structure and frontal lines. Therefore, these results can provide references for treating frontal lines, to a certain extent.

LEVEL OF EVIDENCE: 3

Ultrasonographic analysis of facial skin thickness in relation to age, site, sex, and body mass index

BACKGROUND

Numerous nonsurgical but invasive cosmetic procedures are performed blindly in the dermis or subcutaneous fat layer of the facial skin.

OBJECTIVES

To measure the numerical skin thickness of the facial areas where dermatological procedures are performed by applying ultrasound techniques, and to make it possible to estimate the skin thickness by investigating the influence of several individual constitutional factors such as age, sex, and body mass index (BMI), so that these variables can be applied to estimate skin thickness.

MATERIALS AND METHODS

Skin thickness was measured at eight different facial points using an ultrasound machine (Affiniti 50; Philips Inc.). Demographic data were gathered using questionnaires. Manual BMI was calculated from the weight and height of each participant, and individual BMI measurements were performed using a body composition analyzer.

RESULTS

In terms of whole skin thickness, the thickest point was the mouth corner, and the thinnest point was the lateral forehead. The thickest point in the epidermis was the chin, and the thinnest point was the nasolabial fold. The thickest point in the dermis was the corner of the mouth, and the thinnest was the lateral forehead. Full skin thickness and dermal thickness were mostly lower in females. Skin thickness was not significantly correlated with BMI.

CONCLUSION

The skin thickness at different points on the face was variable, and realistic data about skin thickness can be obtained by in vivo ultrasonographic analysis of the skin.

Applied anatomy of the layers and soft tissues of the forehead during minimally-invasive aesthetic procedures

BACKGROUND

An increasing demand of minimally-invasive aesthetic procedures of the forehead concomitantly leads to higher numbers of adverse events. Adequate application of anatomical knowledge is required to increase safety and efficacy of different minimally-invasive aesthetic procedures in this anatomical region.

OBJECTIVE

To describe the layered anatomy of the forehead soft tissues with respect to their thicknesses and how they relate to different minimally-invasive aesthetic treatments.

METHODS

A total of n = 85 healthy study participants (69 females and 16 males) with a mean age of 40.84 ± 10.9 years and a mean body mass index of 22.65 ± 2.6 kg/m² were investigated with ultrasound-based imaging to measure the thickness of different forehead soft tissues.

RESULTS

The mean overall soft tissue thickness of the forehead was measured to be 4.18 ± 0.7 mm for the entire study population. Increasing BMI values correlated statistically significantly with increasing thickness of all measured forehead soft tissues with exception of the frontalis muscle. On a statistically significant level, males showed thicker forehead soft tissues than females, with exception of the retrofrontalis fat and the frontalis muscle.

CONCLUSION

On basis of the findings obtained in this study, basic treatment principles can be derived and improved for the injection of neuromodulators, hyaluronic acid as well as the application of polydiaxonane (PDO) threads and micro-focused ultrasound. Precise knowledge and thorough understanding of the layers and soft tissues of the forehead is required to guarantee safe and effective procedures in this aesthetically important facial region.

Pinch Anatomy of Forehead: An Injection Guide for Forehead Filler Treatment

With the popularity of filler injections globally, more and more injectors are using them for facial shaping and reversing the aging changes of the face. Detailed knowledge of facial anatomy, especially of important vessels and tissue planes is essential for injectors. While performing filler injections, injectors tend to pinch the tissue layers with their non-dominant hand for ease of doing the procedure. Such deformational forces cause some changes in the anatomy of tissue layers held in a pinch. During a deep pinch, the important arteries in that area can get pulled up in the pinch's tissue layers, or they can stay in their position being unaffected by pinching. The 'pinch and pull' can also improve the tissue space for injections, by pulling away the mobile tissue layers from the fixed ones. Knowledge of the 'pinch anatomy' in the forehead can be used to the injector's advantage to avoid important arteries and place filler in the correct plane. By knowing the anatomical changes during the pinched state of tissue layers, filler injections in the forehead can be performed with relative safety in the correct tissue plane.

Anatomical Injection Guidelines for Glabellar Frown Lines Based on Ultrasonographic Evaluation

When botulinum neurotoxin (BoNT) is injected to treat glabellar frown lines, the corrugator supercilia muscle (CSM) and procerus muscles are the main targets. Although there have been many studies on the treatment of glabellar frown lines, no study has confirmed the dynamic movement under ultrasonography (US). This study examined and evaluated dynamic muscle movements under US, thereby providing more effective BoNT injection guidelines for glabellar frowning. Glabellar frowning was categorized as either Type A or B. Type A is the general frowning pattern in which vertical wrinkles are made by contracting the CSM and procerus muscles (81%, n = 13). On US images, the procerus muscle thickens and the bilateral CSMs contract. Type B is an upward frowning pattern demonstrating upward elevation of vertical wrinkles due to hyperactive contraction of the frontalis muscle during frowning (19%, n = 3). On US images, the hypoechoic frontalis muscle thickens, forming horizontal forehead lines. After BoNT injection into the CSM and frontalis muscle but not the procerus muscle, Type B patterns showed improvements in the vertical crease and horizontal forehead line. Both types showed improvement in glabellar frown lines after conventional injection, but the horizontal forehead line did not improve in Type B. Type B wrinkles improved after additional injections into the frontalis muscle. This study provided novel anatomical findings related to the injection of glabellar frown lines with BoNT. Preliminary analysis and optimized procedures using US will enable more effective and safer injections.

The Change of Plane of the Supratrochlear and Supraorbital Arteries in the Forehead-An Ultrasound-Based Investigation

BACKGROUND

Injecting soft tissue fillers into the deep plane of the forehead carries the risk of injection-related visual compromise due to the specific course of the arterial vasculature.

OBJECTIVES

The aim of this study was to investigate the 2- and 3-dimensional location of the change of plane of the deep branch of the supratrochlear and supraorbital artery, respectively.

METHODS

A total of 50 patients (11 males and 39 females; mean age, 49.76 [13.8] years, mean body mass index, 22.53 [2.6] kg/m2) were investigated with ultrasound imaging. The total thickness and the distance of the arteries from the skin and bone surface were measured with an 18-MHz broadband compact linear array transducer.

RESULTS

The deep branch of the supraorbital artery changed plane from deep to superficial to the frontalis muscle at a mean distance of 13 mm (range, 7.0-19.0 mm) in males and at 14 mm (range, 4.0-24.0 mm) in females and for the deep branch of the supratrochlear artery at a mean distance of 14 mm in males and females (range, 10.0-19.0 in males, 4.0-27.0 in females) when measured from the superior orbital rim.

CONCLUSIONS

Based on the ultrasound findings in this study, it seems that the supraperiosteal plane of the upper and lower forehead could be targeted during soft tissue filler injections because the deep branches of both the supraorbital and supratrochlear arteries do not travel within this plane. The superficial plane of the lower forehead, however, should be avoided due to the unpredictability and inconsistent presence of the central and paracentral arteries.

LEVEL OF EVIDENCE: 4

Ultrasonography Analysis of Vessels Around the Forehead Midline

BACKGROUND

Filler injection into the glabella is well known to be a highly dangerous procedure due to the high risk of embolism and intravascular injection. Although it is conventional practice to insert the cannula into the middle of the forehead to perform injections into the glabella or radix, vascular structures can be observed in this region during anatomic dissection procedures.

OBJECTIVES

The aim of this study was to characterize the blood vessels around the forehead midline in order to provide crucial anatomic information for ensuring the safety of noninvasive procedures involving the forehead and glabella.

METHODS

Ultrasonography image scanning was performed at the following 4 points on the forehead midline: trichion (P1), metopion (P2), halfway point between metopion and glabella (P3), and glabella (P4). The courses and locations of vessels were identified and classified according to their proximity to the forehead midline.

RESULTS

Vessels coursing within 0.75 cm either side of the forehead midline were found in 34% to 50% of individuals. Arteries running near the forehead midline tended to be dominant on the right side of the forehead except in the P4 area. About half of the individuals had vessels in the P4 area, of which 96.7% were veins.

CONCLUSIONS

The present results indicate that there are superficial vessels running close to the midline of the forehead. This anatomic information can explain the higher incidence of vascular complications during conventional aesthetic procedures. To ensure safety, the cannula entry point or needle puncture point for glabella augmentation should be reconsidered.

Three-Dimensional Evaluation of the Depressor Anguli Oris and Depressor Labii Inferioris for Botulinum Toxin Injections

BACKGROUND

Botulinum toxin type A (BoNT-A) injection administered at an inappropriate site or depth can produce an unwanted change in facial animation because the depressor anguli oris (DAO) and depressor labii inferioris (DLI) muscles are partially overlapped. Therefore, simple BoNT-A injection guidelines, based on 3-dimensional (3D) facial anatomic references and landmarks, would be very useful.

OBJECTIVES

The aim of this study was to establish novel BoNT-A injection guidelines that include the soft tissue thickness at the lower perioral region. Data were acquired with a 3D scanning system combined with dissections in order to obtain accurate injection sites and depths for the DAO and DLI.

METHODS

3D scans of the facial skin, superficial fat, and facial muscle surface were performed in 45 embalmed cadavers. The thicknesses of the skin and subcutaneous layer were calculated automatically from superimposed images at each of 5 reference points (P) in the perioral region.

RESULTS

In every case (100%), P3 and P5 were located in the DLI and DAO areas, respectively (45/45). Therefore, we defined P3 as the "DLI point" and P5 as the "DAO point." The soft tissue thicknesses at the DLI and DAO points were 6.4 [1.7] mm and 6.7 [1.8] mm, respectively.

CONCLUSIONS

The P3 and P5 described in this study are effective guidelines that only target the DLI and DAO. Clinicians, specifically, can easily use facial landmarks, such as the cheilion and pupil, to assign the DLI and DAO points without any measurement or palpation of the modiolus.

Clinical anatomy considerations on the muscular and vascular components of the midface by ultrasonographic imaging

The first signs of face aging appear in the midface, so procedures such as botulinum toxin and filler injections are performed there. However, no guidelines based on clinical anatomy describing the muscular and vascular components in vivo have been published. The aim of this research was to describe the depths of the midface muscles and the locations of vessels using ultrasonographic (US) imaging. US was applied at 12 landmarks on the midface in 88 volunteers (49 males and 39 females; 19-36 years) to detect sex differences in the depths of muscles and the locations of the vessels. The depths of the orbicularis oculi (OOc), levator labii superioris alaeque nasi (LLSAN), and zygomaticus minor (Zmi) differed significantly with sex at P7 (p = 0.001) and P8 (p = 0.017), P1 (p = 0.028), and P4 (p = 0.035), respectively. The facial artery, facial vein, angular artery, angular vein, and perforator vessels were found at P9, P2 and P10, P1, P1 and P5, and P8, P11 and P12, respectively. The findings indicate that the depths of the OOc, LLSAN, and Zmi muscles differ between the sexes and that the vessels appear at specific landmarks. This information could help in developing anatomical guidelines for several procedures.

Neonatal wearable device for colorimetry-based real-time detection of jaundice with simultaneous sensing of vitals

Neonatal jaundice occurs in >80% of newborns in the first week of life owing to physiological hyperbilirubinemia. Severe hyperbilirubinemia could cause brain damage owing to its neurotoxicity, a state commonly known as kernicterus. Therefore, periodic bilirubin monitoring is essential to identify infants at-risk and to initiate treatment including phototherapy. However, devices for continuous measurements of bilirubin have not been developed yet. Here, we established a wearable transcutaneous bilirubinometer that also has oxygen saturation (SpO2) and heart rate (HR) sensing functionalities. Clinical experiments with neonates demonstrated the possibility of simultaneous detection of bilirubin, SpO2, and HR. Moreover, our device could consistently measure bilirubin during phototherapy. These results demonstrate the potential for development of a combined treatment approach with an automatic link via the wearable bilirubinometer and phototherapy device for optimization of the treatment of neonatal jaundice.

Histological and Clinical Appraisal of Distribution and Long Acting New Hyaluronic Acid into the Subcutaneous Fat of the Forehead to Improve Horizontal Lines

BACKGROUND

A new hyaluronic acid (HA) was appraised to improve forehead horizontal lines (FHL). Histological analysis correlated the gel distribution with clinical findings and also with wrinkle depth, 48 h and 12 months after HA application.

METHODS

The new filler composed by 24 mg/ml of HA cross-linked with BDDE 2.0 ppm was injected into the subcutaneous fat, just beneath the dermis, through a retrograde backflow injection technique applied in sequence. Biopsies were taken with a 3.0-mm-diameter skin punch before HA application, 48 h and 12 months after HA application for histological evaluation.

RESULTS

Subcutaneous application created a compact cylindrical filament as pattern of gel distribution, which acted as strut raising the FHL to the level of the surrounding tissues. Diameter average of the filament 48 h after HA application was 1.18 mm and at month twelve 0.34 mm. The residual amount of the gel at month twelve ensured the long acting of the HA into the subcutaneous fat. FHL depth of 251.83 µm before HA application and 190.20 µm after 12 months indicated that the residual amount of gel at month twelve still projected FHL.

CONCLUSION

High cohesivity of HA and low density of forehead subcutaneous fat caused the gel to take the form of a compact cylindrical filament. The small amount of gel still presenting into the subcutaneous fat 12 months after application validated the long acting of the HA. Evidence-based analysis showed that this new filler might be considered a safe alternative for improvement in the FHL.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effective Locations for Injecting Botulinum Toxin into the Mentalis Muscle; Cadaveric and Ultrasonographic Study

The mentalis muscle is now considered key structures when performing procedures for rejuvenating the lower face. The aim of this study was to determine the anatomical morphology and location of the mentalis muscle and thereby provide anatomical information for facilitating clinical procedures designed to rejuvenate the lower face. Forty-four adult hemifaces from five Thai cadavers and 21 Korean cadavers were dissected to identify the locations of the mentalis muscle. Sixty-six hemifaces from 33 healthy young Korean subjects were included in an ultrasonographic study. The depth of the mentalis muscle below the skin surface, the thickness of the mentalis muscle, and the distance from the bone to the mentalis muscle were measured at the two points that were 5 mm lateral to the most-prominent point of the chin. The mentalis muscle was classified into two types based to its shape: in type A (86.4%, 38 of the 44 cases) it was dome shaped in three dimensions, while in type B (13.6%, 6 of the 44 cases) it was flat. The mentalis muscle was present mostly at the area 5–10 mm from the midsagittal line and 20–30 mm from a horizontal line connecting the mouth corners. The mentalis muscle was present between depths of 6.7 to 10.7 mm below the skin. This new information about the location of the mentalis muscle may help when identifying the most effective and safe botulinum toxin injection points and depths during esthetic procedures for weakened facial rhytides on the lower face.

Ultrasonographic and Three-Dimensional Analyses at the Glabella and Radix of the Nose for Botulinum Neurotoxin Injection Procedures into the Procerus Muscle

Botulinum neurotoxin (BoNT) injections are widely used for facial rejuvenation procedures, and the procerus muscle is a major target in cases of glabellar transverse lines or rhytids. Although there have been many cadaveric studies of the procerus, its depth and thickness have not been investigated thoroughly. The aim of this study was to measure the depth and thickness of the procerus and identify the location of the intercanthal vein using ultrasonographic (US) imaging and the three-dimensional scanning method, which is needed to know to avoid side effects during BoNT injections. The morphology of the procerus was classified into two types based on the US images obtained at the glabella. The procerus was located deeper below the skin surface at the glabella than the sellion (3.8 ± 0.7 mm versus 2.7 ± 0.6 mm). The width of the procerus in US images increased from the sellion (10.9 ± 0.2 mm) to the glabella (14.5 ± 4.6 mm), whereas its thickness decreased (from 1.6 ± 0.6 mm to 1.1 ± 0.5 mm). The intercanthal vein was located 5.1 ± 4.0 mm superior to the sellion and 3.0 ± 0.6 mm below the skin’s surface. The present findings provide anatomical knowledge as well as the reference location information for use when injecting BoNT into the procerus.