5.3 Results

Results of intraoperative gross SMAFS variations showing various types of SMAFS are in Table 5.1. In cases of thin and membranous SMAFS, the density was decreased, tone was decreased, flaccidity was increased, elasticity was increased, and the SMAFS was soft and pliable. In these cases, the superficial fatty layer was practically nonexistent, and the fibro-aponeurotic and muscular layers were merged and in the form of a membrane. The muscle fibers were thin, long, stretched out, relatively atrophic, and membranous. In cases of thick and fatty SMAFS, consistency was somewhat harder, and it was more resistant, rigid, less elastic, more dense, and with increased tone. In these cases, superficial fatty layer was considerably increased. In cases of broken down (Island SMAFS), with gaps, very thin, and fragile SMAFS, elasticity was increased and tone and density were decreased considerably, while flaccidity was increased considerably. In these cases, the muscle layer was found to be considerably atrophic. In cases of fleshy SMAFS, tone, density, and thickness were increased, while elasticity was decreased. Superficial muscle layer was hypertrophic in these cases. In cases of mixed SMAFS, mixed characteristics were noted depending on the amount of tissue present in the SMAFS; for example, in cases of fibrofatty or fleshy-fatty SMAFS, tone, density, and thickness were increased, while elasticity was decreased. In case of fibrofatty SMAFS, fibroaponeurotic and fatty layers were found to be thick, whereas, in case of fleshy-fatty SMAS, muscle layer was found to be hypertrophic, and fatty layer was considerably increased. In case of fibrous SMAFS, tone, thickness, rigidity, and density were increased, while elasticity and flaccidity were decreased. In these cases, fatty layer was nonexistent, while fibro-aponeurotic and muscular layers were found to be fibrotic, scarred, and hard.

Table 5.1 Gross SMAFS variations in a study of 800 facelifts

Table 5.2 Results of Classical, Delta, S-lift, and Transcutaneous facelifts according to SMAFS type

SMAFS type Classical Delta-lift S-Lift TCFL lift

+++ (excellent), ++ (good), + (satisfactory), +/− (variable), and

– (poor)

Results of Classical, Delta, and S-lift according to SMAFS type are in Table 5.2. In cases of membranous SMAFS, results of Classical/Delta/S-lift were considered as excellent (+++) in 80% of cases, and good (++) in 20% of cases (Figs. 5.1 and 5.2). In case of fatty SMAFS, after liposuction (closed/open), and after subsequent plication/lift, results were considered as good (++) in 60% of cases and as satisfactory (+) in 40% of cases. In cases of fleshy SMAFS, results of facelift were considered as good (++). In cases of mixed SMAFS, after liposuction (closed/open) and plication/lift, results were considered as satisfactory

(+). In case of fibrous SMAFS, results were found to be poor (−). In case of transcutaneous facelift, results were good (++) in case of membranous SMAFS in 80% 0f the cases and satisfactory (+) in 20% of the cases. Results were found to be satisfactory (+) in case of fleshy SMAFS, variable (+/−) in case of mixed SMAFS, and poor (−) in cases of Island, fatty, and fibrous SMAFS.

5.4 Discussion

5.4.1SMAS and SMAFS: Concept and Variations

The SMAS (superficial musculoaponeurotic system) described by Mitz and Peyronie in 1976 was an important landmark in surgical facial anatomy [1]. The SMAS concept was considered essential for a successful and

a

Fig. 5.2 (a) Fatty SMAFS. (b) Preoperative patient with thick moderately fatty SMAFS. (c) After modified temporal and retro-auricular lift with debulking, plication, lifting, and attachment of SMAFS to the temporal and mastoid bones

b

b

c

durable facelift. According to Mitz and Peyronie, SMAS is an extension of superficial cervical fascia into the face. It is continuous throughout the face and neck. Its thickness varies from region to region and from patient to patient. It is dense and thick over the parotid gland. Traced superiorly toward the zygomatic arch, it is termed temporoparietal fascia within the temporal region and galea within the scalp, both of which are substantial in terms of thickness [2]. As it is traced medially into the cheek, overlying the masseter and buccal fat pad, it becomes thinner and less distinct. In the malar region, it is quite thin and comprises the epimysium of the elevators of upper lip [3]. SMAS ensheathes the superficial mimetic muscles, platysma, zygomaticus major and minor, and risorius; fibrous septa connect the SMAS to the overlying dermis of skin. Therefore, mimetic muscles, SMAS, and skin function together as a single anatomical unit in producing facial movements. In view of the authors, however, the superficial mimetic muscles constitute a part of this system, which they call as SMAFS. The deeper layer of SMAS has no vertical fibrous connections. The deeper layer of cervical fascia continues into the face as the parotid-masseteric fascia. Some authors suggest that this layer is also part of SMAS. There appear to be two subdivisions of SMAS: (1) a suprazygomatic and (2) an infrazygomatic division. SMAS is attached firmly to the periosteum at the nuchal line posteriorly and at the mastoid process. Traced anteriorly, this attachment continues toward the zygomatic arch where it splits into two divisions: the upper division is attached below the eyebrow up to the dorsum of nose [4]; the lower subdivision descends downward at an angle of 45° to the lower lip margin. It is basically this lower subdivision which is clinically relevant in surgical facelifting [5]. The parotid fascia, risorius muscle, depressor anguli oris muscle, and platysma muscle can be pulled up together as one unit [6].

It appears that there are two major embryologically related subdivisions that interact at the buccal commissure. Those derived from the lower animal sphincter colli profundus muscle include the helmet-like muscles of skull, and mask-like muscles of the central face. The second division is related to the primitive platysma muscle, which in lower mammals consists of broad sheet of muscles covering the lower face and neck. In humans, it consists of platysma, risorius, depressor anguli oris, and the postauricular muscles, as well as the parotid fascia, which has lost its muscle fibers and

has become fibrotic [7]. The components of the primitive platysma muscle lie in one plane. This plane, however, is not apparently continuous with the subgaleal plane of the forehead and scalp or with the lip elevators of the central face. Recognition of the disparate derivation of the two muscular systems makes it easier to understand why SMAFS is not continuous over the entire head and neck. However, embryological and acquired variations of SMAFS are somewhat more common than previously thought.

The platysma covers the upper parts of the pectoralis major and deltoideus, across the clavicle and mandible, joining the parotid fascia posteriorly, and enclosing the sternocleidomastoid attached to the mastoid process [8]. The SMAFS starts with the superficial fascia over the platysma (also embedded in platysma fibers), and extends over the mandible, to include the parotid fascia and the zygoma. The middle cervical fascia, invests the two layers of the infrahyoid muscles (has a superficial, middle, and deep sheath) and is attached to the hyoid bone and clavicle.

The frontal branch of facial nerve, unlike other nerve branches that lie deep to the deep facial fascia, is an anomaly. Once the frontal branch crosses the zygomatic arch, it travels underneath the temporoparietal fascia in the temporal region and then penetrates this layer peripherally to reach the deep surface of frontalis muscle. Therefore, if the temporoparietal fascia is violated during dissection, injury to this nerve can take place [9]. The area at greatest risk for damage to the temporal branch can be more easily demonstrated by drawing a line from the ear lobe to the lateral edge of the eyebrow and from the tragus to a point just above and behind the highest forehead crease. The temporal branches are at equal risk in the area defined by these lines, especially where they cross the zygomatic arch. At this point, the frontal nerve and its branches are especially vulnerable since they lie in the SMAFS just beneath its superficial fatty layer, and over the bony prominence [9]. The approximate path of the ramus to the frontalis muscle can be traced by drawing a line from 0.5 cm below the tragus to a point 1.5 cm above the lateral eyebrow. It is most vulnerable as it crosses the mid-zygomatic arch [9].

The S-lift procedure, in which the SMAFS is plicated, lifted, and attached to the periosteum of the zygomatic arch, can result in damage to the frontal nerve or its branches. Since the mid-zygomatic arch is the most vulnerable area, suturing of the SMAFS to

the periosteum here should be avoided or one should proceed with extreme delicacy. Even suturing the SMAFS at the proximal zygomatic arch can result in nerve damage. In addition, pretragal pain and tension have been reported. If more knots are applied to the 2/0 Prolene sutures here, the knots can extrude through the skin. Damage to the temporal branch results in loss of function of the frontalis muscle, which derives its sole innervation from one solitary ramus that 85% of the time has no cross branches with the zygomatic nerve [9]. The forehead appears flat, the eyebrow falls to a lowered ptotic position, and there is inability to raise the eyebrow. There is no interference, however, with the eyelid closure. The upper part of orbicularis oculi and corrugator supercilii show little functional or cosmetic deficit. Single branching patterns are usual; however, as many as six or more branches have been traced crossing the zygomatic arch. It is probable that these variations account more commonly than previously thought. Therefore, in cases of multiple branching patterns, the S-lift procedure shows little functional or cosmetic deficit to the frontalis and other muscles of innervation by the frontal nerve. Despite the variety of branching patterns, these nerve fibers are nearly always medial and inferior to the frontal branch of the superficial temporal artery, which is easily palpated and serves a useful landmark in identifying the frontal nerve. The authors use the Delta-lift technique, in which the SMAFS is plicated well away from the frontal nerve/ marginal mandibular nerves pathways, and therefore nerve injury practically never takes place. In case of S-lift, the authors attach Prolene to the proximal zygomatic arch. The authors have practically never seen damage to the frontal nerve using this technique.

The marginal mandibular nerve exits the parotid gland approximately 4 cm beneath the base of the earlobe near the angle of mandible. In 81% of patients, the nerve lies above the mandibular border. In 19% of cases, it lies inferior, although posterior to the facial vessels. The marginal mandibular nerve then crosses the facial vessels, and from this point anteriorly it runs superior to the mandibular border [10]. Where the facial artery and vein cross the mandibular border is a very useful landmark. The facial artery can be palpated just anterior to the angle of mandible along the anterior masseter border and serves as a quick method for localizing the marginal mandibular nerve [10]. Here, the nerve is superficial as it crosses over the facial vessels, and it is at this point that marginal mandibular nerve

injury can take place [10]. It is very important to remember that as long as subcutaneous dissection remains superficial to SMAFS and platysma, motor nerve injury will be prevented [9, 10].

5.4.1.1 Sleep Lines

The underlying attachments of SMAFS become reflected superficially as skin folds, following certain chronic sleeping patterns. For example, sleep lines in the face become manifest as lines along the lower nasolabial fold and marionette areas, mid-cheek line, preauricular lines, arcus marginalis along the lower lid, nasal line along levator labii superioris, and as lines along the glabellar attachments. An oblique line appears across crow’s feet, which reflects pressure on arcus marginalis attachment of SMAFS. These sleep lines become more prominent when compression is applied on tissues below these lines. Similarly, sleep line at the level of the levator labii superioris muscle from the SMAFS attachment becomes more prominent, when compression is applied on tissues toward the nose. Oblique fold across the marionette line reflects central condensation of SMAFS at the anterior mandibular ligament. Central cheek fold reflects the central condensation of SMAFS in the mid-cheek area. Skin folds may be created from SMAFS attachments from fibrous bands during the healing of scars.

5.4.1.2 Membranous SMAFS

This is the most common variant of SMAFS. Membranous SMAFS is usually thin, however, rarely, it is thick. In case of membranous SMAFS, adequate lift is achieved using three SMAFS sutures and plicating it below the zygomatic arch, as in a Classical/ Delta-lift, or attaching it to the proximal periosteum of zygomatic arch, as in an S-lift using vertical U and horizontal O Prolene sutures. The lift is stable, and the results are longer lasting and usually excellent (Fig. 5.1) if the surgeon is an experienced rhytidectomist.

The results of Classical/Delta/S-lift are very satisfying when the SMAFS is thin and membranous as plication is easy and accurate and it is possible to lift the SMAFS considerably. SMAFS flaps have become obsolete in our hands now and are not created.