The current understanding of the aging process suggests that a complex interplay of changes at all tissues levels, from bone through fat and muscle to skin, leads to the stigmata of an aged face. The role of volume loss in this process has been clearly documented.1–31–31–3 In youth, facial contours reflect light in smooth arcs that allow one to focus on the eyes and lips without intervening shadows. With age and volume loss, what were previously convex surfaces become concave, leaving shadows and rhytides that are signs of aging.
One of the earliest, but often most subtle, signs of aging is volume loss in the temple. With deflation of the temporal fossa, the arc of light surrounding the orbit is lost. This interrupts the smooth transition from the brow to the zygomatic arch and unmasks the lateral aspect of the orbital rim. The tail of the brow is displaced inferiorly and posteriorly, causing it to appear shorter.4 With more pronounced volume loss, one can appear “skeletonized,” with a pinched look to the upper face. Although this occurs at a relatively early age in many patients, especially thin patients, it is rarely a specific presenting complaint. Often, the physician must point it out when the patient presents for other cosmetic issues.
Several treatments have been used for augmentation of hollowed temples, including fat grafting and surgical implants. Soft tissue fillers in the temple have gained significant popularity recently because of their ease of use and predictable results. They are not without risk; however, significant adverse events occur and include the possibility of permanent visual loss.5 However, with proper knowledge of the anatomy, the authors believe that soft tissue fillers can be safely and reliably used to augment the area.
With adequate revolumization of the temple, one can restore a natural-appearing convexity to the area and also lift the face and brow upward to provide proper support for further treatment of the midface and lower face. It is very important not to overcorrect this area.
As with all injectable procedures, excellent knowledge of anatomy of the area is crucial to safe and effective treatment. This is especially true in regard to the temple, with a number of vessels and nerves in the area and also proximity to the orbit.
The temporal fossa is a shallow depression on the lateral aspect of the skull. The boundaries are the superior temporal line superiorly and posteriorly, the frontal process of the zygomatic arch anteriorly, and the temporal process of the zygoma inferiorly6 (Figure 1). It is quite sizable, with posterior extension to nearly the end of the parietal bone. For the purposes of cosmetic augmentation, the anterior portion ending around the hairline is of most concern.
This area contains multiple tissue layers that include, from superficial to deep skin, subcutaneous fat, temporoparietal fascia (or superficial temporal fascia), deep temporal fascia (divided into a superficial and deep layer), loose areolar tissue, temporalis muscle, periosteum, and bone6 (Figure 2).
Within the temporoparietal fascia courses the temporal branch of the facial nerve. This motor nerve crosses directly over the zygomatic arch to supply the frontalis, orbicularis oculi, and corrugator supercilii. It is responsible for elevating the brow and superior lid and also the efferent limb of the corneal reflex.
Within the temporal fossa, three levels of vessels course, all branches of the external carotid.7 The superficial temporal artery and vein lie in the subcutaneous plane just above the temporoparietal fascia (Figure 1). The pulse of the superficial temporal artery is often palpable. The middle temporal artery and vein lie just below the superficial vessels, in the space between the superficial layer of the deep temporal fascia and the temporoparietal fascia. The deep temporal vessels lie below the temporalis muscle on top of the deep layer of the temporal fascia. Together the middle and deep temporal vessels supply the temporalis muscle.
The temporalis muscle is a muscle of mastication responsible for elevation and retraction of the mandible. With age, the muscle loses mass. Interestingly, a recent study has demonstrated that increasing masticatory effort while the masseter is paralyzed by botulinum toxin effectively increases the volume of the temporalis muscle.8
When considering the placement of the vessels in the area, there are three potential planes for safe injection within the temporal fossa: subcutaneous, deep to the temporoparietal fascia, and deep below the temporalis muscle on the periosteum.6 The previous literature has suggested that hyaluronic acid (HA)-based fillers should be placed in either the subcutaneous plane or deep to the temporoparietal fascia, whereas collagen-stimulators–like poly-L-lactic acid or calcium hydroxylapatite should be placed deep to the temporalis muscle.6,9–116,9–116,9–116,9–11 The authors suggest that HA fillers are best and most safely placed deep to the temporalis muscle, directly on periosteum, to provide safe and long-lasting revolumization of the area.
Less often, product can be placed in the subcutaneous plane for more superficial volume loss or rhytides. With this level of injection, to avoid contour irregularities, care must be taken to inject only small amounts of low viscosity material and adequately massage the material after injection.
Complications can occur with all injectable procedures but may be minimized with proper knowledge and technique. Adverse events associated with filler placement in the temple are typically mild and transient but can on rare occasions be severe and permanent. The most common reported adverse event with injection into the area is transient bruising, often of the lower eyelid.12 Other mild complications include transient prominence of the superficial vessels, headache, and tenderness that may be accentuated with mastication.
With 3 sets of vessels coursing through the temporal fossa, vascular compromise is a real and very serious complication that must be avoided through proper product preparation and injection technique. This can occur through either direct intravascular injection or compression of the vessel by high volumes of product nearby. Vascular occlusion is manifested by blanching of the skin and acute onset of severe pain. This is followed by a dusky, mottled discoloration of the skin that, if left untreated, may progress to necrosis.13
Intravascular injection of product in the temple may very rarely lead to blindness. This has been reported in several times in the literature.14,1514,15 A recent review by Beleznay and colleagues5 has found 5 confirmed cases of blindness after injection in the temple. Three of these cases occurred when injecting exclusively at the temple, one with silicone oil and the second with autologous fat. The remaining 2 cases occurred when injecting both the temple and forehead at the same session, both with autologous fat. There have been many cases reported of blindness from Korea. Most of these have been with autologous fat. The external and internal carotid systems are intimately linked, and with sufficient product and injection pressure, retrograde flow of product can occur that then flows distally to the retinal artery system. Visual acuity changes have been shown to occur more commonly and with more severity with autologous fat transfer than HA filler injection.5,14,155,14,155,14,15
The authors suggest the use of an HA filler for the initial treatment of volume loss in the temple area. It should be noted that no filler has specific approval for use in the temple area, and injection of any filler, including Food and Drug Administration–approved HA fillers, is considered off-label for volumizing the temple. Hyaluronic acid fillers offer a reliable and reversible method of augmenting the area. Suitable products are ones with a higher viscosity or G′ so as to resist any downward pull exerted by the soft tissue of the midface and lower face. Depending on injector preference, the filler can be diluted with normal saline and/or lidocaine to help with ease of injection and reduce the incidence of lumpiness and uneven correction.
The patient should be counseled before treatment on all possible side effects, including blindness, and should be instructed on expected aftercare. The area to be injected should be thoroughly cleaned with chlorhexidine and alcohol to minimize risk of infection and possible biofilm formation. The patient should be marked while in the upright sitting position. If desired, the patient can then be placed in the partially recumbent or fully supine position for comfortable injection.
Hyaluronic acid can be injected safely and effectively into the temple with either a needle or cannula technique. For needle injection, the authors recommend a 27g or 30g ½” needle. Before injection, the superficial temporal artery should be palpated, marked, and avoided. Starting at the tail of the brow, the injector should palpate the temporal fusion line. This represents the superomedial boundary of a safe treatment window, and injections should be placed inferior and lateral to this line. Additionally, the zygomatic arch should be palpated and any injection should be placed at least 1.5 cm or 1 finger breadth above so as to avoid the middle temporal vein as recently described by Jung and colleagues.7 The final landmark is the hairline with injections being placed anteriorly. Injection beyond the hairline is safe but offers little cosmetic augmentation. Within these boundaries described lies a safe window for injection where product should be deposited directly on periosteum7 (Figure 3).
To reach the periosteal plane, the needle is inserted perpendicular to the skin and directed deep until contact is made with the bone (Figure 4). The syringe should then be aspirated until air is seen to ensure that it is not placed intravascularly. A note of caution, this is not foolproof and may not always work, particularly with smaller gauge needles. A depot injection of filler can then be placed using a steady and slow injection. Injecting slowly is paramount to help avoid complications. The authors recommend beginning with 0.5–1 mL of product per side per treatment. To prevent product diffusion posterior to the hairline, a finger can be held firmly at the hairline during injection. For most bolus injections into the window described, product can easily be massaged for even distribution throughout the temporal fossa region.
Swift16 has recently described an alternative methodology, wherein a single injection point 1 cm superior and 1 cm lateral to the tail of the brow is used. This point lies within the window of injection described, and both techniques have recreated reliable and safe injections.
The temporal fossa can also be treated using a cannula technique. This is best reserved for more superficial filling in the subdermal plane because placing filler in the periosteal plane with a cannula is difficult and painful for the patient. To fill the area using a cannula, the authors recommend an entry point 1.5 cm superior to the zygoma just anterior to the hairline. A small superficial injection of lidocaine should be made to area followed by insertion of a 22-g needle. Topical anesthetic can be used as well before puncture with the needle as alternative to injected lidocaine. The entry point can then be cannulated by a 27-g cannula placed in the subcutaneous plane. The cannula should fanned throughout the temporal fossa with product placed using slow, steady retrograde injection technique. As with needle placement, the area should be thoroughly massaged to ensure even correction.
Minor complications such as bruising and pain can often be unavoidable but may be minimized with proper preoperative evaluation, injector technique, and aftercare. If possible, patients should avoid any medications or supplements before treatment that may increase bruising, such as aspirin, nonsteroidal anti-inflammatory drugs, fish oil, garlic, and gingko. Direct pressure should be applied to any injection site with notable bleeding after needle withdrawal. Prominence of the superficial veins is common after injection, especially in patients with thin skin, but reliably resolves within a few days. As the temporalis muscle is involved with mastication, patients often experience pain in the area that is aggravated by chewing. Patients should be instructed to eat a diet of soft foods immediately after treatment to help minimize this pain. If intense swelling occurs, treat with ice, pressure, and corticosteroids if necessary.
Avoidance of vascular compromise and ocular complications is paramount with injection to the temple. For this reason, the authors recommend an HA filler placed in the avascular, periosteal space. It is, however, still possible to push down and pin a vessel even with needle placement just above bone. Aspiration is always recommended before injection but should not be considered 100% reliable for ensuring that there is no possibility of intravascular injection. To achieve retrograde flow of product down the arterial system, one must overcome systolic pressure. For this reason, product should always be injected slowly and steadily without significant force. If one encounters the need to forcefully inject to discharge the product, clogging of the needle or cannula may have occurred, and the syringe should be withdrawn and the needle replaced and reinserted until injection can occur with minimal force.
Signs of vascular or visual compromise include skin changes distant from injection site, severe skin pain, visual acuity change, and ocular pain. If any of these are noted during injection, the needle should be withdrawn immediately. The injection area should be thoroughly and firmly massaged, ideally with the application of heat. Nitroglycerin paste should be liberally applied to the area to achieve maximum vasodilation. The injected area should be flooded with hyaluronidase to attempt to dissolve the product responsible for the vascular compromise. Additional treatments that may be of benefit for vascular occlusion include aspirin, sildenafil, and hyperbaric oxygen. If ocular problems are noted, seek urgent consultation with an ophthalmologist. Retrobulbar hyaluronidase should be considered in very rare cases of sudden blindness.17
Hollowing of the temple is an early sign of aging that, when corrected, can lead to significant patient and practitioner satisfaction. The area is one of the complex anatomy with multiple nerves and vessels running in relatively thin tissue planes. Proper anatomically knowledge is required to avoid potentially severe complications. In this study, the authors present a reliable technique to safely and effectively augment this often undertreated area of the aging face.
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