Anatomy and Histology of the Frontalis Muscle

Mapping cortical excitability in the human dorsolateral prefrontal cortex

BACKGROUND

Transcranial magnetic stimulation (TMS) to the dorsolateral prefrontal cortex (dlPFC) is an effective treatment for depression, but the neural effects after TMS remains unclear. TMS paired with electroencephalography (TMS-EEG) can causally probe these neural effects. Nonetheless, variability in single pulse TMS-evoked potentials (TEPs) across dlPFC subregions, and potential artifact induced by muscle activation, necessitate detailed mapping for accurate treatment monitoring.

OBJECTIVE

To characterize early TEPs anatomically and temporally (20-50 ms) close to the TMS pulse (EL-TEPs), as well as associated muscle artifacts (<20 ms), across the dlPFC. We hypothesized that TMS location and angle influence EL-TEPs, and specifically that conditions with larger muscle artifact may exhibit lower observed EL-TEPs due to over-rejection during preprocessing. Additionally, we sought to determine an optimal group-level TMS target and angle, while investigating the potential benefits of a personalized approach.

METHODS

In 16 healthy participants, we applied single-pulse TMS to six targets within the dlPFC at two coil angles and measured EEG responses.

RESULTS

Stimulation location significantly influenced observed EL-TEPs, with posterior and medial targets yielding larger EL-TEPs. Regions with high EL-TEP amplitude had less muscle artifact, and vice versa. The best group-level target yielded 102% larger EL-TEP responses compared to other dlPFC targets. Optimal dlPFC target differed across subjects, suggesting that a personalized targeting approach might boost the EL-TEP by an additional 36%.

SIGNIFICANCE

EL-TEPs can be probed without significant muscle-related confounds in posterior-medial regions of the dlPFC. The identification of an optimal group-level target and the potential for further refinement through personalized targeting hold significant implications for optimizing depression treatment protocols.

[Anatomy of the frontal region]

The forehead is an anatomic region located between the frontal hairline cranially, the eyebrow and the glabella caudally, and the anterior border of the temporal fossa laterally on both sides. Its vertical situation, due to the telencephalon growth, is specific of the human species. From surface to deep planes, the skin and sub-cutaneous fat pads are described first. The muscular plane is constituted of the frontal muscles elevators of the forehead and the eyebrow, and the depressors which are the procerus and orbicularis oculi muscles superficially, the depressor supercilii muscle, and the corrugator supercilii in a deep plane. The galea aponeurotica, located deep to the frontal muscles, is a fibrous lamina on which the muscles of the skull insert. There is a sexual dimorphism of the frontal bone. The male forehead has extensive supraorbital bossing, and above this there is often a flat area, in teh femalethe supraorbital bossing is often nonexistent and above, there is a continous mild curvature. Blood supply to the forehead is given by an anterior pedicle constituted by the supraorbital and supratrochlear vessels and a lateral pedicle made of the anterior branches from the superficial temporal vessels. The sensory innervation of the forehead is given by the ophtalmic nerve which divides in frontal, nasociliar and lacrymal nerves. The motor innervation is given by the temporal ramus of the facial nerve which passes laterally to the zygomatic arch, and gives the innervation of the frontal, corrugator supercilii and procerus muscles.

Prefrontal oscillatory slowing in early-course schizophrenia is associated with worse cognitive performance and negative symptoms: a TMS-EEG study

BACKGROUND

Abnormalities in dorsolateral prefrontal cortex (DLPFC) oscillations are neurophysiological signatures of schizophrenia thought to underlie its cognitive deficits. Transcranial magnetic stimulation with electroencephalography (TMS-EEG) provides a measure of cortical oscillations unaffected by sensory relay functionality and/or patients' level of engagement, which are important confounding factors in schizophrenia. Previous TMS-EEG work showed reduced fast, gamma-range oscillations and a slowing of the main DLPFC oscillatory frequency, or natural frequency, in chronic schizophrenia. However, it is unclear whether this DLPFC natural frequency slowing is present in early-course schizophrenia (EC-SCZ) and is associated with symptom severity and cognitive dysfunction.

METHODS

We applied TMS-EEG to the left DLPFC in 30 EC-SCZ and 28 healthy control (HC) subjects. Goal-directed working memory performance was assessed using the "AX" Continuous Performance Task (AX-CPT). The EEG frequency with the highest cumulative power at the stimulation site, or natural frequency, was extracted. We also calculated the local Relative Spectral Power (RSP) as the average power in each frequency band divided by the broadband power.

RESULTS

Compared to HC, EC-SCZ had reduced DLPFC natural frequency (p=0.0000002, Cohen's d=-2.32) and higher DLPFC beta-range RSP (p=0.0003, Cohen's d=0.77). In EC-SCZ, the DLPFC natural frequency was inversely associated with negative symptoms. Across all participants, the beta-band RSP negatively correlated with the AX-CPT performance.

CONCLUSIONS

A DLPFC oscillatory slowing is an early pathophysiological biomarker of schizophrenia that is associated with its symptom severity and cognitive impairments. Future work should assess whether non-invasive neurostimulation can ameliorate prefrontal oscillatory deficits and related clinical functions in EC-SCZ.

Eyebrow Lift: Open-Book ROOF Transposition and Orbicularis-Frontalis Sliding Maneuver

This article delves into innovative surgical techniques, the open-book ROOF (retro-orbicularis oculi fat) transposition technique (OBRoof) and the orbicularis-frontalis sliding maneuver (OFS), designed for eyebrow and upper eyelid rejuvenation in the aging process. Emphasis is placed on understanding the dynamic changes occurring within the forehead and eyebrow envelope's five layers and their intrinsic relationships as well as the impact of the ROOF ptosis causing upper eyelid hooding. The OBRoof technique is highlighted for its effectiveness in addressing ptotic volume, offering a rejuvenated appearance by relocating volume to the supraciliary region.In the OFS, we explore the concept of extensive dissection above the upper border of the eyebrow to allow for free repositioning of the eyebrow. The stabilization is based on deep-plane facelift concepts, as the orbicularis oculi muscle corresponds to the superficial muscular aponeurotic system, and it is anchored to the deep layers (periosteum) by passing through the frontal muscle.In summary, this article provides a comprehensive exploration of innovative and minimally invasive techniques for eyebrow and upper eyelid rejuvenation, shedding light on their anatomical foundations, procedural intricacies, and the potential for achieving natural and lasting outcomes.

Optimizing Botulinum Toxin A Administration for Forehead Wrinkles: Introducing the Lines and Dots (LADs) Technique and a Predictive Dosage Model

This study introduces the Lines and Dots (LADs) technique, a new approach for administering botulinum toxin type A (BoNT-A) in treating forehead wrinkles. (1) Background: BoNT-A application patterns in the forehead often rely solely on the anatomy of the frontalis muscle. The LADs technique proposes a combination of anatomical features with nerve pathways. (2) Methods: The technique employed a grid system aligned with the supraorbital and supratrochlear nerve pathways and used an electronic acupuncture pen for validation. This study analyzed treatment outcomes for efficacy and safety and proposed a predictive model for BoNT-A dosage. (3) Results: LADs was associated with a high satisfaction rate and low side effect incidence. The predictive model followed BoNT-A Units=0.322×Muscle Pattern Code+1.282×Line Type Code+2.905×Severity Pre-Treatment+3.947. (4) Conclusions: The LADs technique offers an alternative approach to treating forehead wrinkles, optimizing efficacy while minimizing the BoNT-A dose required.

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

Use of LetibotulinumtoxinA for Aesthetic Treatment of Asians: A Consensus

Treatment of wrinkles and dynamic lines with botulinum toxin has been a routine practice for years in aesthetic clinical settings. The effective treatment of wrinkles requires a comprehensive understanding of facial expression muscles and their interactions, the mechanism of action of botulinum toxin, and individual patient preferences. The dose adjustment practice and injection technique of physicians are affected by cultural differences; most Asian patients prefer natural-looking results. This article aims to present an expert consensus on the injection sites, doses, and levels of botulinum toxin for various indications in Asians, with the hope of providing guidance to some clinicians. This consensus paper reviews LetibotulinumtoxinA for patient evaluation, dosage, and delivery techniques in Asians from the time LetibotulinumtoxinA was approved up to December 2022. Panelists proposed individualized treatment plans for botulinum toxin type A (BTxA) treatments in 3 areas-wrinkle removal, contour adjustment, and face lifting-for Asians based on their extensive experience and knowledge of facial anatomy. When using a different BTxA, clinicians should start with a conservative dose and carefully individualize the treatment for each patient, and adjust it according to feedback to obtain a higher satisfaction level.

LEVEL OF EVIDENCE: 5

The significance of split-face studies and electromyography in forehead rejuvenation

BACKGROUND

Botulinum toxin is a neurotoxic substance with a wide range of uses, from the treatment of musculoskeletal spasms to antiaging regimens by improving wrinkles. Split-face studies in which drugs are injected in the right and left sides of the faces have been actively conducted in botulinum toxin studies. In this study, we aimed to investigate the reliability of a split-face study for determining the effectiveness of botulinum toxin based on eyebrow height and movement, and electromyography results.

METHODS

Thirty-one women aged 35 to 55 years were included in the study. Eyebrow height was measured as the distance from the eyebrows to the upper eyelid margin on the primary gaze, and eyebrow movement was measured as the distance when the forehead was wrinkled for 5 seconds. A noninvasive method was used for electromyography of the frontalis muscles.

RESULTS

No statistically significant differences in right and left eyebrow heights and movements, and electromyography findings (p= 0.256, p= 1.000, and p= 0.978, respectively) were found. Pearson correlation analysis showed that electromyography muscle activity is positively associated with eyebrow movement, respectively (p< 0.001).

CONCLUSION

We advocate the reliability of split-face study and the usefulness of electromyography of frontalis muscle in forehead rejuvenation research.

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.

A quantitative analysis of the brow shape after frontalis muscle contraction

PURPOSE

To measure the changes of the eyebrow's contour after frontalis muscle (FM) contraction.

METHODS

Two consecutive pictures of the eyes and frontal region of 36 volunteers (15 men and 21 women) were obtained with the forehead relaxed and upon maximal frontalis muscle contraction. Bézier lines representing the brows' contours, obtained with the ImageJ software, were graphically sampled with a resolution of 0.025 mm. The contours of the relaxed and elevated brows were compared regarding the position of the contour peak (CP), the degree of elevation of brow central point, and the medial and lateral areas outlined between the brow contours before and after frontalis contraction. The asymmetry of the brow contour after FM contraction was calculated by the Naeije formula as (Medial-Lateral)/(Medial + Lateral). A difference of 10% or less between the lateral and medial areas was taken as a cutoff value for symmetrical brow elevation.

RESULTS

In 62 (86.1%) of the eyes, the location of the brow's CP was lateral to the brow's midpoint. When the brows were raised, the CP of 60% of the brows was displaced medially and 40% laterally. The motion of the CP with medial displacement (mean = 3.7 mm) was significantly larger than those displaced laterally (mean = 1.9 mm) decreasing the number of brows with lateral peaks from 62 (86.1%) to 54 (75%). No difference was observed between the mean elevation of the central point of the brow for males (7.9 mm (3.2 SD) and females (7.4 mm, 3.0 SD). In 58.3% of the sample, the positional change of the medial and lateral sectors of the brows was symmetrical, and among the 41.7% asymmetrical cases, the elevation of the medial side was higher than the lateral in 66.7% of the brows.

CONCLUSIONS

The brow changes during FM contraction concur well with the anatomic data of the FM shape. The contour of most brows is displaced toward the medial direction when the brow is elevated. The pattern of brow shape change is an indication of the FM anatomy and must be carefully analyzed before any procedure involving the FM, such as chemodenervation injections or frontalis slings for blepharoptosis correction.

Human Frontalis Muscle Innervation and Morphology

Due to its clinical importance and due to a suggestion regarding the afferent innervation, the microscopic appearance of the frontalis muscle was investigated.

The Anatomy behind Eyebrow Positioning: A Clinical Guide Based on Current Anatomic Concepts

BACKGROUND

The position of the eyebrow is known to reflect emotional status and to provide a plethora of nonverbal information. Although the eyebrow has no direct attachment to underlying bone, it is subject to the interplay between the various periorbital muscles, which when acting together, permit important nonverbal cues to be conveyed. Understanding the balance and interplay between these muscles is of crucial importance when targeting the periorbital area with neuromodulators. The authors' aims were to summarize current anatomic and clinical knowledge so as to provide a foundation that physicians can rely on to improve and increase the predictability of patient outcomes when treating the periorbital region with neuromodulators for aesthetic purposes.

METHODS

This narrative review is based on the anatomic and clinical experience of the authors dissecting and treating the periorbital region with specific focus on the glabella and the forehead.

RESULTS

This narrative review covers (1) a brief description of the relevant periorbital muscle anatomy, (2) an analysis of each muscle's contribution to various facial expressions, and (3) an anatomic and physiologic simulation of the muscular effects of specific neuromodulator injection sites.

CONCLUSION

By understanding functional anatomy of the periorbital muscles and combining this knowledge with individualized assessment and treatment planning, it is possible to achieve aesthetically pleasing, predictable, and reproducible treatment outcomes that positively impact perception of nonverbal cues when administering neuromodulators.

Firing rate trajectories of human occipitofrontalis motor units in response to triangular voluntary contraction intensity

During voluntary contractions, limb muscle motor unit (MU) firing rates accelerate over a small force range and saturate in response to increasing contraction intensity. In comparison, facial muscles are cranially innervated, and some function without crossing joints. Therefore, the MU firing rate behaviour and characteristics of saturation were explored in a facial muscle that moves skin and facia during voluntary contractions. We evaluated the firing rate trajectory in response to triangular voluntary contraction ramps in the occipitofrontalis muscle of 11 adult participants. Intramuscular electromyography of the frontalis aspect was used to record single MU trains followed up to maximal voluntary contraction intensities. Firing rates were measured from each MU sample, with the firing rate trajectory fit as both exponential (i.e., saturation) and linear models that were compared statistically. The rate coding behaviour of frontalis MUs was broad, as the peak firing rate (mean 76 Hz) was ninefold greater than the firing rate at recruitment threshold (mean 8 Hz). Across 20 MU samples, only 40% (8 MU samples) were determined to have a firing rate trajectory that saturated and had slow acceleration in response to increasing voluntary drive until maximum. The exponential curve of the firing rate trajectory had ~ tenfold lower acceleration as compared to prior reports in limb muscles. These results across all MU samples indicated that voluntary control of the frontalis muscle requires relatively slower accelerating or linear MU firing rate trajectories, suggesting that movements of facial muscles may be directly representative of extrinsic synaptic inputs.

Signal-To-Noise Ratio Calculations to Validate Sensor Positioning for Facial Muscle Assessment Using Noninvasive Facial Electromyography

The evaluation of neuromodulator treatment outcomes can be performed by noninvasive surface-derived facial electromyography (fEMG) which can detect cumulative muscle fiber activity deep to the skin. The objective of the present study is to identify the most reliable facial locations where the motor unit action potentials (MUAPs) of various facial muscles can be quantified during fEMG measurements. The study population consisted of five males and seven females (31.0 [12.9] years, body mass index of 22.15 [1.6] kg/m²). Facial muscle activity was assessed in several facial regions in each patient for their respective muscle activity utilizing noninvasive surface-derived fEMG. Variables of interest were the average root mean square of three performed muscle contractions (= signal) (µV), mean root mean square between those contraction with the face in a relaxed facial expression (= baseline noise) (µV), and the signal to noise ratio (SNR). A total of 1,709 processed fEMG signals revealed one specific reliable location in each investigated region based on each muscle's anatomy, on the highest value of the SNR, on the lowest value for the baseline noise, and on the practicability to position the sensor while performing a facial expression. The results of this exploratory study may help guiding future researchers and practitioners in designing study protocols and measuring individual facial MUAP when utilizing fEMG. The locations presented herein were selected based on the measured parameters (SNR, signal, baseline noise) and on the practicability and reproducibility of sensor placement.

OnabotulinumtoxinA Treatment for Moderate to Severe Forehead Lines: A Review

Background:

With onabotulinumtoxinA approved for the treatment of glabellar and crow’s feet lines and, most recently, for forehead lines (FHL), it is possible to simultaneously treat multiple areas of the upper face that are of high concern and treatment priority for aesthetically oriented individuals. This review aims to present key insights on the use of onabotulinumtoxinA for the treatment of moderate to severe FHL.

Methods:

Double-blind, placebo-controlled registration trials of onabotulinumtoxinA for the treatment of FHL were included. Using findings from 3 such published studies, we discuss key concepts and clinical experience for the treatment of moderate to severe FHL with onabotulinumtoxinA (20 U in the frontalis and 20 U in the glabellar complex, with/without 24 U in crow’s feet lines), including injection pattern, dose selection, efficacy and safety data, and considerations for patient selection.

Results:

Across the 2 pivotal phase 3 studies, responder rates on investigator- and subject-assessed measures of appearance of FHL severity were significantly higher with onabotulinumtoxinA versus placebo for the treatment of FHL at day 30 (P < 0.0001), and results were maintained through 3 cycles of onabotulinumtoxinA.

Conclusions:

OnabotulinumtoxinA treatment also resulted in high patient satisfaction rates. The incidence of eyebrow and of eyelid ptosis was low, and no new safety signals were detected. OnabotulinumtoxinA is safe and effective and an appropriate option for patients with moderate to severe FHL encountered in clinical practice.

Botulinum Toxin to Treat Horizontal Forehead Lines: A Refined Injection Pattern Accommodating the Lower Frontalis

BACKGROUND

When treating horizontal forehead lines with botulinum toxin type A the traditional approach requires that injection points should stay 1.5 to 2 cm above the orbital rim to avoid brow ptosis. Failure to treat the lower frontalis may potentially cause worse rhytides in the lower forehead.

OBJECTIVES

The aim of this study was to present a refined injection pattern accommodating the lower frontalis and evaluate its clinical efficacy and safety.

METHODS

Patients were categorized into 4 types according to the patterns of their forehead wrinkles. Moderate and severe wrinkles in the upper forehead were treated by the "safe zone" technique. Mild wrinkles and rhytides in the lower forehead were treated by the Microbotox technique. Standard photographs and measurements were taken before and after treatment. The effect on wrinkle reduction and changes in brow heights were assessed.

RESULTS

In total, 330 treatments were followed up in the clinic, and 246 treatments were followed up by telephone. Among the 330 treatments, 213 were evaluated in our clinic 2 to 4 weeks later, and the patients who received these treatments were recruited for effect evaluation and brow height measurements. The posttreatment severity of forehead wrinkles was significantly reduced (P < 0.05), and brow heights remained unchanged (P > 0.05). No severe adverse events were documented. Patient satisfaction was quite high.

CONCLUSIONS

The refined injection pattern is an effective and safe technique to treat horizontal forehead lines. The Microbotox technique enables treatment of the lower frontalis without changes in brow position.

LEVEL OF EVIDENCE: 3

A personalized treatment approach of frontalis muscle with botulinum toxin A (Bont-A) related to functional anatomy: case studies

Background: The forehead is one of the most frequent sites of botulinum toxin (Bont-A) application. To date, few data are available about the anatomy of the frontalis muscle. Its anatomy is highly heterogeneous in Caucasian people. Consequently, personalized treatments with botulinum toxin-A (Bont-A) are needed to obtain good esthetic results and to reduce side effects. Recently, a study on cadavers found four anatomical shapes of the frontalis muscle, corresponding to four horizontal wrinkle patterns in live patients.Objective: To perform a personalized, reproducible, and safer treatment with Bont-A of the forehead, by classifying patients according to four specific anatomical shapes of the frontalis muscle related to skin wrinkle patterns during contraction.Methods: We treated four patients classified according to the four anatomic types (I, II, III, and IV). The patients' forehead was divided into 21 areas and matched with 4 horizontal wrinkle patterns. Detecting different activities of the muscle in the different areas of the forehead, treatment injections were performed with a different dose, dilution, and at different anatomical layers (intramuscular or intradermal) per point.Conclusions: We confirmed four different wrinkle patterns after forehead contraction according to the anatomical shape of the frontalis muscle. This allows us to perform a tailored treatment with Bont-A. Nevertheless, some patients with atypical patterns still need "ad hoc" treatment.

Locational Relationship between the Lateral Border of the Frontalis Muscle and the Superior Temporal Line

BACKGROUND

The frontalis is a representative target muscle for botulinum neurotoxin type A injections aimed at treating horizontal wrinkles in the forehead region. However, a lack of information regarding the shape and thickness of the frontalis may lead to unexpected side effects.

METHODS

This study dissected hemifaces of 44 embalmed Korean and Thai cadavers and performed ultrasound examinations on 20 Korean volunteers. Two anatomical types were identified: (1) the lateral portion of the frontalis covered the superior temporal line in type I, and (2) the lateral border of the frontalis and the superior temporal line almost coincided in type II. A horizontal line was drawn laterally from the midpoint between the metopion and the glabella, and landmarks F1, F2, and F3 were defined as points where this horizontal reference line intersected with vertical lines from the midpoint of the pupil, the lateral canthus, and the lateral orbital rim, respectively.

RESULTS

Type I was more common than type II [84 percent (37 of 44) versus 16 percent (seven of 44)]. When the lateral border of the frontalis ran along the border, there were no cases in which the superior temporal line was not visible. The mean minimum distance in type I was 10.53 mm. The muscle thicknesses at F1, F2, and F3 were 1.80 ± 0.44 mm (mean ± SD), 1.61 ± 0.37 mm, and 0.11 ± 0.04 mm, respectively.

CONCLUSIONS

This study yielded data on the location and thickness of the lateral border of the frontalis. An anatomical study-based, ultrasound-guided injection technique can achieve reliable results when noninvasive treatment is applied to the forehead area.

Key Parameters for the Use of AbobotulinumtoxinA in Aesthetics: Onset and Duration

Time to onset of response and duration of response are key measures of botulinum toxin efficacy that have a considerable influence on patient satisfaction with aesthetic treatment. However, there is no overall accepted definition of efficacy for aesthetic uses of botulinumtoxinA (BoNT-A). Mechanical methods of assessment do not lend themselves to clinical practice and clinicians rely instead on assessment scales such as the Frontalis Activity Measurement Standard, Frontalis Rating Scale, Wrinkle Severity Scale, and Subject Global Assessment Scale, but not all of these have been fully validated. Onset of activity is typically seen within 5 days of injection, but has also been recorded within 12 hours with abobotulinumtoxinA. Duration of effect is more variable, and is influenced by parameters such as muscle mass (including the effects of age and sex) and type of product used. Even when larger muscles are treated with higher doses of BoNT-A, the duration of effect is still shorter than that for smaller muscles. Muscle injection technique, including dilution of the toxin, the volume of solution injected, and the positioning of the injections, can also have an important influence on onset and duration of activity. Comparison of the efficacy of different forms of BoNT-A must be made with the full understanding that the dosing units are not equivalent. Range of equivalence studies for abobotulinumtoxinA (Azzalure; Ipsen Limited, Slough UK/Galderma, Lausanne CH/Dysport, Ipsen Biopharm Limited, Wrexham UK/Galderma LP, Fort Worth, TX) and onabotulinumtoxinA (Botox; Allergan, Parsippany, NJ) have been conducted, and results indicate that the number of units of abobotulinumtoxinA needs to be approximately twice as high as that of onabotulinumtoxinA to achieve the same effect. An appreciation of the potential influence of all of the parameters that influence onset and duration of activity of BoNT-A, along with a thorough understanding of the anatomy of the face and potency of doses, are essential to tailoring treatment to individual patient needs and expectations.

The Practical Use of AbobotulinumtoxinA in Aesthetics

Botulinum toxin (BoNT) has been approved for aesthetic use since 2002. Since then, clinical studies and expert use have informed our understanding of how BoNT exerts its clinical effect and the practical use of this product across a number of aesthetic applications. This review discusses the clinical properties and characteristics of abobotulinumtoxinA, which patients are suitable for its use, and how it can be utilized to treat facial rhytides.

Small-incision frontalis muscle transposition flap for lateral eyebrow ptosis repair

PURPOSE

To describe a novel technique to correct lateral eyebrow ptosis using a frontalis muscle transposition flap.

METHODS

The charts of all patients undergoing eyebrow ptosis repair using a frontalis muscle transposition flap from December 2013 through April 2014 were reviewed to describe the surgical technique.

RESULTS

Sixteen patients underwent eyebrow ptosis repair using a frontalis muscle pedicle flap during the study period. Briefly, after local infiltration, a lateral forehead rhytid was marked and incised for approximately 1.5 cm. Blunt dissection exposed the frontalis-orbicularis angle, the frontalis-orbicularis insertion, and the lateral extent of the frontalis muscle. A pedicle flap of lateral frontalis muscle was created, trimmed, and transposed laterally in graded fashion to achieve the optimal eyebrow height and contour. The incision was closed with 5-0 polypropylene suture. All patients reported improvement in eyebrow position.

CONCLUSIONS

This novel technique provides frontalis muscle elevatory force to the lateral eyebrow through a small incision to improve eyebrow ptosis. Further study, including objective measures of long-term results, is required.