Introduction

The temporal region is delimited superiorly by the temporal line (temporal suture), inferiorly by the zygomatic arch, anteriorly by the external orbital rim, and laterally by the hairline (Fig. 6.8).

In a young person, the temples are flat or slightly convex, but they become concave with age. The upper third of the face narrows, which causes apparent shortening and the ptosis of the eyebrow, with the tail of the eyebrow “falling” into the temporal region. ¹ According to Raspaldo, ² the degree of aging of the temporal region can be classified into four stages, characterized as follows (Fig. 6.9):

1. 
   

   Convex or flat temporal fossa.

   
   
2. 
   

   Slight depression.

   
   
3. 
   

   Concavity of the temporal fossa, some visibility of vessels, and ptosis of the tail of the eyebrow.

   
   
4. 
   

   Skeletization of the temporal fossa and visible bones, clear visibility of vessels, and severe concavity.

Anatomy

The temporal region is composed of the skin, subcutaneous tissue, superficial temporal fascia or temporoparietal fascia, temporal fat pad, deep temporal fascia (divided into the superficial and deep layers), buccal fat pad (Bichat’s fat pad), temporal muscle, and periosteum of the temporal bone (Fig. 6.4–6.7 and6.10–6.19). ³

The superficial temporal artery (STA) and the deep temporal artery supply this region. The STA is the smaller of the two terminal branches of the external carotid artery. It originates in the parotid gland, posteriorly to the neck of the mandible, and crosses the zygomatic arch about 10 mm anteriorly to the tragus. It divides into the transverse facial artery, the zygomatico-orbital artery, and the parietal and frontal branches. It crosses the temporal region in its posterior quadrant and above the superficial temporal fascia. The deep temporal artery is a branch of the maxillary artery, the largest of the terminal branches of the external carotid. It has an anterior and a posterior branch, located between the temporal muscle and the periosteum. It is important to note that despite being a branch of the external carotid, the STA anastomoses with branches of the internal carotid, such as the supraorbital artery. Therefore, an intravascular injection could reach the internal carotid system through retrograde flow and occlude the central retinal artery. Though rare, the main complication is blindness. It is, therefore, vital to have in-depth knowledge of the local anatomy and the appropriate technique before performing any procedures in this region.

The periorbital veins, the frontal branch of the superficial temporal vein (STEV), the branches that drain from the temporal muscle, the zygomatico-orbital and zygomaticotemporal veins, and the sentinel vein drain to the middle temporal vein (MTV), which crosses the temporal region between the superficial and deep layers of the deep temporal fascia. The MTV anastomoses with the STEV above the zygomatic arch and connects with the cavernous sinus through the periorbital veins, which is why there is a risk of embolization in the cavernous sinus after intravenous injection. ⁴ ,. ⁵

Technique

The techniques used are divided into superficial and deep techniques (Fig. 6.20–6.36). The basic steps for either technique consist of:

• 
  

  Marking the area to be filled and observing that the temporal fossa is frequently deeper in the region immediately lateral to the orbit and above the zygomatic arch.

  
  
• 
  

  Choosing the most appropriate hyaluronic acid (HA): To do this, it is important to assess the thickness of the local skin, application plane, and degree of aging.

Superficial Technique

This technique involves performing a retrograde injection in the subcutaneous tissue through a microcannula, using HA for the superficial or middermis. Administer the injection below the visible vessels; the volume used depends on the degree of aging. Generally, 1 ml per side is used. Massage the area well (Fig. 6.1).

Treating the temporal region is a challenge because the local skin is thin and tends to form irregularities after injection. Lambros ¹ presented an alternative technique for filling the subcutaneous plane with HA diluted in physiological saline solution (PS) at a ratio of 2:1 (PS to HA). With the absorption of PS, HA is distributed more uniformly. This dilution technique, and inserting HA at this site, is considered off -label.

Deep Technique

Deposit the HA bolus for the middermis and deep dermis or the volumizer below the temporal muscle, in the supraperiosteal plane. Insert the needle perpendicularly to the skin, until you reach the periosteum. Aspire, inject slowly, and do not move the needle during the injection. Generally, 0.5 to 1 ml per side is used, and the site of injection should be massaged well (Fig. 6.2).

The Swift technique for deep filling of the temporal region involves inserting the needle perpendicularly (1 cm above the external orbital rim and 1 cm below the temporal suture) until the periosteum is reached. This technique is considered safer because the deep temporal artery and the STA do not flow through this region. ⁴

Table 6.1 shows the main differences between the two techniques described. When necessary, both can be used on the same patient. This is called a combined technique (Fig. 6.3).

Table 6.1 Characteristics of the superficial and deep techniques

Superficial technique	Deep technique
Injection with microcannula	Injection with needle
Application technique: linear retrograde injection	Application technique: bolus
Subcutaneous injection plane	Supraperiosteal injection plane
Hyaluronic acid in the	Hyaluronic acid in the
middermis/deep dermis (with or without dilution)	middermis/deep dermis or volumizer

Complications

Common adverse effects include edema, which can last up to 72 hours; temporary congestion of the local vessels; irregularities; hematoma; and pain at the site of injection. Serious complications, such as embolism and thrombosis, have also been reported.

References