Glabella/central brow

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14 Glabella/central brow

Hema Sundaram, Jean Carruthers

Summary and Key Features

• Soft tissue augmentation of the glabella and central brow is increasingly recognized as an important part of the pan-facial volumization strategy for many patients

• Augmentation of the glabella and central brow with fillers may be performed to correct age-related volume loss, or for the purposes of enhancement

• The glabella and central brow are anatomically unforgiving with regard to both safety and aesthetic considerations

• An understanding of anatomy and the physicochemical characteristics of fillers (including rheology) drives the selection of appropriate filler products and safe, efficacious injection techniques

• For many patients, the combination of fillers with neuromodulators will produce more a natural-looking rejuvenation than treatment with neuromodulators alone

• Fillers are also of value for patients with residual rhytides after neuromodulator treatment of the glabella and central brow

• A thorough pre-procedural consultation and discussion of realistic objectives are key to optimizing patient satisfaction

• Superficial or deep injection approaches may be employed alone or in combination. For both approaches, hyaluronic acid fillers may be the best option owing to their potential reversibility and excellent safety margin

• Meticulous sterile technique is essential before and during all filler injection procedures to minimize the risk of infection or biofilm.

• When properly performed, filler injections to the glabella and brow have a high rate of patient satisfaction and can profoundly improve the aesthetic appearance of the whole face

Introduction

The glabella and central brow may be considered the last frontier in facial soft tissue augmentation, in that the value of including them in pan-facial volumetry has been recognized only recently.

The recognition of volume loss as a cardinal feature of aging, and the availability of fillers that allowed this volume loss to be more effectively addressed – starting in the US with Food and Drug Administration (FDA) approval of the first hyaluronic acid (HA) filler in 2003 – catalyzed an evolution in our approach to soft tissue augmentation. The emphasis shifted from simply filling in rhytides to the objective of restoring youthful facial contours. For some patients, fillers can be used not just to correct age-related volume loss but also to actually improve upon the contours of their youth and create facial proportions that more closely approximate the ideals of beauty.

Age-related volume loss was first recognized in the lower face and mid-face. Early filler strategies focused on the nasolabial folds and subsequently on correcting volume deficits in the mid-face to secondarily elevate the nasolabial folds. At this time, there was some degree of ‘geographic divide’ between fillers and neuromodulators, with the latter being used more commonly to the upper face. The importance of also restoring volume to the upper face was recognized later, with the realization that age-related volume loss is pan-facial. Filler injection strategies developed for the temples, and now it is understood that true pan-facial volumization for many patients also includes filler implantation in the glabella and forehead, including the central brow.

Advances in our use of fillers have been paralleled by an evolution in our concepts of how best to combine fillers with neuromodulators. The advanced injector now appreciates that fillers can be used synergistically with neuromodulators throughout the face, including the glabella and central brow, rather than being placed differentially. This optimizes results, and potentially also improves their longevity.

The ultimate aim of pan-facial volumization is to restore ideal facial contours. The ideals of facial beauty have been largely preserved across time and cultures. This is probably because these ideals have an evolutionary basis, reflecting youth, good health, and, for women, the presence of sufficient levels of estrogen to confer fertility (Sundaram H). For both sexes, the youthful ideal is a relatively prominent upper and mid-face. In Western cultures, this tapers to a less prominent lower face / jawline in women, and thus a face that is shaped like a heart or inverted triangle. In men, the taper is somewhat less pronounced, with a stronger jawline and more equal proportions of the upper, mid- and lower face resulting in a longer, more rectangular shape.

Asian and other Eastern cultures have historically preferred a more rounded female facial shape, though jawline tapering is still desired. The rounded ideal is seen in images of Indian women dating back to the Indus Valley civilization (3300–1300bc) and Chinese women from the Tang dynasty (ad363–422); in depictions of Queen Maya (the Buddha’s mother); and in Indian poetry from the 5th century ad that exalts the beauty of ‘a face to rival the moon’. Although the traditional Eastern ideal has been somewhat influenced of late by the West, with some Asian women now expressing the desire for a less rounded face and actively seeking the injection of fillers and neuromodulators (e.g. to the masseter muscles) to achieve this, a ‘long face’ is still considered unfeminine. The preference for less angular female facial contours is readily discerned by comparing the movie stars of India’s Bollywood with those of America’s Hollywood. It is important to grasp these cultural differences in perception of beauty and to discuss each patient’s notions of what will enhance her appearance in advance of treatment, since even Asian women who were raised in Western countries may be displeased with soft tissue augmentation that gives them the oval, sculpted look that is currently a hallmark of Caucasian beauty.

In women, a smooth, unfurrowed brow and high, broad, convex forehead contours have been prized since antiquity and enhanced through artificial means. Women of ancient Greece pulled their hair tightly back from their faces to emphasize their foreheads and to lift their brows. Upper face prominence was enhanced in India with forehead decorations such as the bindi, which is still worn in modern times, and the painted forehead designs of the Chinese Tang dynasty served a similar purpose. Renaissance women such as the one depicted in 16th century Italian artist Allori’s Portrait of a Woman and the famous Elizabethan English beauty Lettice Knollys painstakingly plucked their hairlines to achieve the ‘noble brow’. More recently, the 1940s film actress Rita Heyworth had her hairline raised by electrolysis.

Currently, soft tissue fillers are used alone or in combination with neuromodulators for non-surgical improvement of the glabella and forehead, including the central brow. The objective may be corrective, i.e. reduction in rhytides and / or restoration of more youthful contours. Fillers are also used for forehead augmentation – to enhance the convexity and prominence of the forehead in younger patients who have not yet have developed actual volume loss.

Epidemiology and patient selection

Soft tissue augmentation of the glabella and central brow may be performed in the following patients:

1. Patients with residual rhytides following neuromodulator injections. These patients, who generally have some degree of volume loss and decreased skin elasticity, can be identified in advance of neuromodulator injection to the glabella and central brow with a skin stretch test, and counseled at that time regarding the likely need for adjunctive filler. Filler can correct volume loss and compensate to some extent for loss of skin elasticity.

2. Patients who prefer to retain some degree of glabellar and central brow mobility after neuromodulator treatment. Neuromodulator dosing strategies for the glabella and forehead, including the central brow, vary depending on patient preference for a mobile versus a ‘frozen’ look. Patients who wish to retain maximum expressivity and avoid a ‘frozen’ look may be best treated with relatively low doses of neuromodulators to the glabella and forehead, including the central brow, plus adjunctive filler.

3. Patients with volume loss from the glabella and forehead, including the central brow. Glabellar volume loss often assumes the form of two parallel vertical furrows of variable depth. In the forehead including the central brow, volume loss may be focal or more general, respectively resulting in localized or more diffuse, trough-like concavities. Volume loss to the glabella is generally primary and age related. Volume loss to the central brow may also be primary, or secondary to neuromodulator-related atrophy of the frontalis. This is a thin sheet-like muscle and this author has observed anecdotally that it has a propensity to develop atrophic areas in some patients after repeated neuromodulator injections over many years, especially if these injections are of high dosage.

4. Patients desiring augmentation or enhancement of forehead / central brow convexity. There are individual and cultural / ethnic variations in the preference for a convex or even domed forehead. Forehead augmentation has become especially popular in Korea and other Asian countries. It is interesting to note that neuromodulator treatment of the upper face, the most popular non-surgical rejuvenative procedure in the USA, is rarely performed on patients in these countries because they do not tend to frown in the way that Caucasians do.

5. Patients who decline neuromodulator treatment but still wish to improve rhytides in the glabella and central brow regions.

Anatomical considerations

A working knowledge of the anatomy of the glabella and central brow is required in order to optimize both the safety and aesthetic outcome of soft tissue augmentation.

The most superficial tissue plane of the glabella and central brow is the skin, comprising the epidermis and dermis. Beneath this lies the subcutaneous tissue, then the superficial fascia, which covers the underlying muscles. There is loose subgaleal areolar tissue below the muscles, then the periosteum, which represents the deep fascia in this region and rests upon the bone (Fig. 14.1).

image

Figure 14.1 Muscles and tissue planes of the glabella and central brow.

Muscles of the glabella and central brow

Medial brow depressors

The procerus is a small, pyramid-shaped muscle that originates from the fascia overlying the inferior aspect of the nasal bone and the superior aspect of the lateral nasal cartilage. It inserts into the skin of the medial forehead between the eyebrows, where its fibers interdigitate with those of the frontalis muscle. The procerus muscle is usually supplied by temporal and lower zygomatic branches of the facial nerve. It contracts vertically, resulting in movement of the eyebrows medially and down, to produce transverse glabellar lines.

The corrugator supercilii muscles lie below the frontalis muscle. They originate bilaterally from the bone at the medial end of the superciliary arches, travel obliquely and superiorly, and insert deeply into the skin above the midpoints of the orbital arches. The corrugator supercilii muscles are innervated by a nerve plexus originating from the temporal branch of the facial nerve. Their contraction moves the eyebrows medially and down, resulting in vertical lines of the glabella and central brow.

The depressor supercilii muscles are regarded by some as separate muscles and by others as part of the orbicularis oculi or corrugator supercilii muscles. They lie bilaterally between the corrugators and procerus, originating from the medial orbital rims in proximity to the lacrimal bones and inserting on the medial aspects of the orbital arches inferiorly to the corrugator supercilii. Innervation is from branches of the facial nerve. Contraction of the depressor supercilii muscles is considered to result in oblique lines of the glabella and central brow.

Brow elevator

Frontalis, the sole elevator of the eyebrows, is a sheet-like muscle that extends over the forehead, including the central brow, and, since it continues onto the scalp, is also known as the occipitofrontalis muscle. Its form varies; it presents in some individuals as continuous and in others as bifid with two distinct bellies and a midline decussation. It has no bony attachments, originating from the galea aponeurosis, which envelops it and represents the superficial fascia of the forehead. Its fibers blend medially with procerus, laterally with the orbicularis oculi over the zygomatic process of the frontal bone, and it inserts via its connections with the corrugators and orbicularis oculi into the skin of the eyebrows and nose. The frontalis is innervated by the temporal branch of the facial nerve. Its contraction creates horizontal lines in the forehead, including the central brow.

Important nerves, vessels, and other structures

The supraorbital neurovascular bundle emerges on each side from the supraorbital foramen, which is located 2.7 cm from the midline, at the junction of the medial one-third and the lateral two-thirds of the superior margin of the orbital bone. From here, the supraorbital neurovascular bundle pierces the corrugator supercilii and then pierces the surface of frontalis higher up on the forehead. The supraorbital nerve and vessels ramify into branches that innervate the forehead and scalp back to the vertex.

The supratrochlear neurovascular bundle lies more medially and is smaller. The supratrochlear nerve is a branch of the frontal nerve, which is derived from the ophthalmic division of the trigeminal cranial nerve (V). It is located 1.7 cm from the midline and 0.8 cm anterior to the supraorbital nerve. After exiting the orbit under the medial 1 cm of the brow, between the pulley of the superior oblique muscle and the supraorbital foramen, the supraorbital neurovascular bundle curves up on to the forehead close to the bone and beneath the corrugator supercilii and frontalis. It then divides into branches that pierce these muscles and ramify to supply the skin of the lower mid-forehead including the central brow, the skin of the upper eyelid, and the conjunctiva.

It is also important to be aware of the structure of the eyelids. They are multilayered with the middle layer consisting of a sheet of connective tissue known as the orbital septum, which extends to the rim of the bony orbit. The septum thickens as it inserts onto the orbital rim and this thickening is referred to as the arcus marginalis.

Decision-making: selection and preparation of filler product, selection of injection plane

General considerations

The glabella and central brow are anatomically unforgiving areas in regards to both safety and aesthetic considerations.

To ensure safety, it is necessary to visualize the location of vital structures such as nerves and vessels, and to take measures to avoid them when injecting fillers or neuromodulators.

In regard to aesthetics, the slightest overfilling or misplacement of a fraction of a milliliter of filler within the glabella and central brow can cause suboptimal results. It is therefore recommended that HA fillers be used, as contour correction can be performed if needed by removing them in part or fully by the injection of hyaluronidase. Dilution of fillers with saline and / or lidocaine suspension makes them easier to spread with post-injection tissue molding to achieve smooth contours. This is because dilution reduces filler viscosity. Dilution is best performed with the aid of a sterile two-way female-to-female adaptor to which the syringe of filler and another syringe containing the diluent can be attached.

An understanding of structural and functional anatomy and of the physicochemical characteristics of fillers – including the flow-related (rheologic) properties of elasticity (G prime) and viscosity that predict their behavior – informs the selection of appropriate filler products and injection techniques to achieve optimal results (see Box 14.1, Tables 14.1 and 14.2; see also Figs 14.2–14.6).

Box 14.1

Soft tissue fillers currently approved by the US Food and Drug Administration (FDA), under study in the U.S.

Calcium hydroxylapatite

image Radiesse

Cross-linked hyaluronic acid: high concentration (20–25 mg/mL)

image Belotero® Balance

image Juvéderm® Ultra

image Juvéderm® Ultra Plus

image Perlane®

image Restylane®

image Juvéderm® Voluma*

image Emervel fillers*

image Teosyal fillers†

Cross-linked hyaluronic acid: low concentration

image Prevelle® Silk (4.5–6 mg/mL)

Poly-L-lactic acid

image Sculptra®

Polymethyl methacrylate with bovine collagen

image Artefill®

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