Neck rejuvenation

13 Neck rejuvenation

Anatomy and the effect of aging

The critical anatomical areas in the neck are the cervicomental angle, the submental/submandibular triangles and the gonial angles. The paired anterior bellies of the digastric muscles extend from the lesser cornu of the hyoid bone to the posterior surface of the mandible on each side of the symphysis. The motor innervation of the anterior belly of the digastric muscle is the mandibular division of the trigeminal nerve. The muscles act as weak depressors of the mandible. Excision produces no noticeable functional deficit but does cause retro-positioning of the hyoid bone and, therefore, a favorable deepening of the cervicomental angle.1

The borders of the submandibular triangles are formed by the digastric muscles and the inferior border of the body of the mandible. These bilateral triangles each contain the submandibular salivary gland, facial artery and vein, lingual nerve and the marginal mandibular branch of the facial nerve. The submandibular gland may produce a bulge in the submandibular triangle if it is hypertrophied and/or ptotic.

In the lower face, the marginal mandibular nerve exits from under the anterior-inferior portion of the parotid gland. In this location the course is deep to the parotid masseteric fascia. It runs horizontally along the lower border of the mandible passing from deep to the parotid masseteric fascia into the subSMAS cleavage plane and continuing superficial to the facial vessels to innervate the depressor anguli oris and mentalis muscles.2 This is the area most prone to marginal mandibular nerve injury during facelift surgery (Fig. 13.1). Both the lingual and hypoglossal nerves lie deep to the submandibular gland. Therefore, intracapsular resection of the gland minimizes the risk of bleeding and nerve injury.

Three important planes exist in the neck: the superficial plane between the skin and the platysma; the intermediate plane composed of the platysma and the interplatysmal fat; and the deep plane containing the subplatysmal fat, the anterior belly of the digastric muscles and the submandibular glands.3

The platysma muscles are thin, bilateral structures that are continuous with the SMAS in the face.4,5 The platysma is vertically oriented in the neck extending from the clavicles inferiorly and predominantly horizontal in the lower face (Fig. 13.2). The platysma has osseous connections to the mandible as it ascends over the mandibular border. And while separate, the platysma is intimately related to the mandibular septum, both structures sending fibers to the mandibular border.6 Reece et al. recently described the mandibular septum. They suggest that the septum may act as a sling impeding fat descent below the mandible and hence lead to jowl formation.6 Because the platysma is continuous with the SMAS and has minimal bone contact, laxity in the SMAS is transmitted to the neck.2,4,5,7 There are three variations of platysmal anatomy in the submental region:

Type III (10%)

No interdigitation of the platysma muscles (Fig. 13.3).8

With age, the retaining ligaments attenuate from the free medial edges of the platysma muscle to the deep cervical fascia. The platysmal edges then pull away from the underlying structures, shorten and form visible bands.

In addition to skin quality, soft tissue laxity and fat maldistribution, developmental variations of the bony anatomy, will have a decided effect on the aging process. Specifically, sagittal and vertical microgenia and/or a skeletal Class II appearance will have a negative impact on support of the lower face and neck. Similarly an obtuse gonial angle or mandibular plane will negatively affect lower facial aging. Conversely, correction of these skeletal deformities will have a decidedly positive effect on the facial aging process (Fig. 13.4).

The hallmark of a youthful face is a well-contoured neck.912 Several criteria of a youthful neck have been defined including a curving or blunt cervicomental angle of 105–120°, a distinct inferior mandibular border, a slightly visible thyroid cartilage and a visible anterior sternocleidomastoid border (Fig. 13.5).13,14 Knize grades the degree of neck deformity on a I–IV scale. Grade I represents an ideal neck angle and increasing numbers indicate increasing deformity. Using this system, he documented consistent and significant long-term neck correction following anterior lipectomy and platysmaplasty.15,16 It is important to note, however, that an isolated necklift in the presence of significant jowling and descent of the neck–face junction will generally not produce a pleasing aesthetic result.3

Effects of aging/disease process

In patients with facial aging the neck and face are ideally treated simultaneously. Therefore, a necklift is an important component of virtually any facelift procedure. Similarly, it is the rare patient who will be best treated by neck surgery alone. While this chapter is devoted to the aging neck, the maneuvers described should be considered as part of the facelift technique. Virtually all techniques used for neck correction can be performed through the submental incision.

Aging in the lower face is due to varying degrees of laxity which develops in the skin, retinaculum cutis and cutaneous ligaments of the face. Which component is most responsible for facial aging dictates the type of face/necklift procedure chosen. The importance of laxity in the lower masseteric cutaneous ligaments as a major factor in the development of the jowl has been established for some time.17 More recently, this anatomy and its implications for aging have been further clarified by Mendelson.2 This information is thoroughly reviewed in Chapter 6. Mendelson’s “premasseteric space” overlies the lower one-half of the masseteric muscle. The roof of the space is the platysma, the posterior border of the masseter represents its posterior border, the inferior border of the mandible and mandibular septum its inferior border, the anterior border of the masseter and the lower masseteric-cutaneous ligaments its anterior border. Superiorly are the stout upper masseteric-cutaneous ligaments. This is a potential space in youth, but becomes a true space with facial aging, expanding and bulging onto the masseteric ligaments. This results in stretching and jowl formation.

In Chapter 11, facelift techniques are reviewed and authors present their preferred method to manipulate the deeper soft tissues of the face. Conceptually, techniques which involve the SMAS are based on the premise that a major component of facial aging is due to laxity in the SMAS and the cutaneous ligaments. Not only do the SMAS procedures correct this laxity, but the SMAS also acts as a vehicle for repositioning lower face and submental fat. Whether SMAS plication,18 SMAS excision and closure (lateral SMASectomy)19 or ligament release, SMAS advancement and reattachment (extended SMAS procedures)912,2023 is superior, is open to question. Furthermore, certain techniques favor a vertical advancement of the SMAS,911,2026 while others utilize an oblique vector.18,19

Laxity in the lower face is transmitted to the neck because the SMAS and the platysma are located in the same plane with minimal bony attachments. Therefore, tightening of the SMAS has a decided effect on the platysma. In sequencing SMAS manipulation in the face and platysmaplasty in the neck, SMAS procedures should be performed first. Theoretically, if the platysmaplasty is done first, this locks the platysma in place and prevents repositioning of jowl and neck fat into the face by SMAS elevation (J. Stuzin, pers. comm.).

In Chapter 11, the MACS lift principle, originally described by Tonnard, was reviewed. In that technique, platysma tightening is accomplished along a mostly vertical vector utilizing purse-string sutures in the cheek. Fogli borrows on and extends this concept by relying on posterior-superior traction on the neck platysma rather than anterior (medial) platysma tightening. He believes that it is counterproductive to separate skin from platysma. He addresses the platysma with a vertically oblique vector, to Lore’s fascia (platysma auricular fascia, or parotid cutaneous ligaments). Higher in the cheek, he utilizes oblique vectors, suturing submalar fat to the malar bone and a running suture continues as an oblique vector ending at the anterior parotid fascia. His technique is predicated on the concept of addressing laxity where the laxity is greatest. Lax SMAS is sutured to immobile areas such as the malar bone and parotid fascia.7

While soft tissue changes associated with facial aging have received widespread attention, the effect of facial aging on the bony skeleton has not. Aside from the clear adverse effect of tooth loss on the lower vertical facial height on the maxilla and mandible, bony changes associated with facial aging have been limited to the correction of developmental abnormalities of the cheek and chin and infraorbital rim.2730 However, certain dicta described in the orthognathic surgery literature should be applied to the aging lower face and neck.27,3134 Rosen has demonstrated that just as expansion of the soft tissue envelope is desirable in the patient with facial aging, expansion of the bony envelope with augmentation techniques should be favored over reduction procedures in the aging face even when taken beyond normal cephalometric bounds.35,36

Horizontal advancement genioplasty tightens suprahyoid musculature, expands the skin envelope and improves the profile (Fig. 13.6), while chin reduction procedures lead to a relative excess of the skin envelope, chin ptosis and an adverse effect on the profile with aging.

Preoperative assessment

An analysis of facial proportions on the patient with facial aging is a good starting point for patient assessment from both a diagnostic and treatment standpoint. This can be done rapidly during the patient examination in the office, as well as from patient photographs after the initial interview. There are a number of good methods of both frontal and profile assessment. The analysis in Figure 13.7 depicts ideal frontal facial proportions, Figure 13.8, the ideal transverse and, Figure 13.9, the ideal proportions in profile. Facial aging is exacerbated by deficiencies in lower vertical facial height (Fig. 13.10) and by lower face sagittal deficiencies (Fig. 13.4). Vertical deficiency in the frontal plane is corrected at the time of facelift/necklift surgery by vertical lengthening genioplasty. Sagittal microgenia is corrected by horizontal genioplasty or alloplastic chin augmentation (Figs 13.4 and 13.6, respectively).

Midface weakness in the pyriform aperture area or the submalar area results in premature aging, deepening of the nasolabial folds and a relative excess of the soft tissue envelope. Expansion of the soft tissue envelope by soft tissue augmentation with fat injection or with a submalar implant has a beneficial effect on facial aging (Fig. 13.11).

An attractive gonial angle may be masked by the fatty neck. Conversely defatting just posterior to the ramus of the mandible and inferior to the gonial angle will define and enhance the lower face. When defatting is combined with SMAS tightening the surgical result is significantly enhanced (Fig. 13.12).

In evaluating the neck proper, aging in the neck may be due to skin excess, fat accumulation, platysma laxity, digastric, submandibular gland abnormalities or anatomic variants such as a low hyoid bone (i.e., abnormalities in the superficial, intermediate or deep planes).3 Evaluation of the skin is relatively straightforward. Marked laxity or excess skin dictates the need for a pre and postauricular incision for proper skin redraping. Mild to moderate skin laxity may be treated by a short-scar facelift approach or submental incision and skin undermining through the submental approach. Numerous authors have stated that skin often need not be removed from the neck during face/neck rejuvenation.1316,27,28,3746 This is due to: (1) the unique ability of neck skin to contract once released from the platysma and (2) more, not less skin, is needed once the obtuse angle of the neck becomes more acute, i.e., the hypotenuse of a triangle is less than its two sides (Fig. 13.13).

The degree of platysmal banding should be assessed and, when present, where the platysma is most lax, i.e., medially. Skin tightening and necklift without platysmaplasty will lead to early platysmal band correction. However, if present and not addressed platysmal bands will invariably recur shortly after surgery.

In evaluating neck fat, assessment should be made both above and below the platysma. While fat above the platysma is generally readily apparent, the amount of fat deep to the platysma is more difficult to gauge. The proper estimate of subplatysmal fat often requires platysma opening for accurate assessment. A reasonable maneuver at the time of the patient exam is to ask the patient to grimace. Fat above the platysma should remain within the examining fingers while subplatysmal fat will be less apparent.

In general, if there is a question as to the presence of subplatysmal fat, the platysma should be opened because of the inaccuracy of preoperative assessment. With regard to neck defatting, the trend is towards conservatism. The majority of defatting is done centrally, over the jowl and posterior to the gonial angle. Skin flaps should be left relatively thick in order to avoid irregularities and an over-resected unnatural appearance of the neck.

Nonsurgical options

Some nonsurgical treatments have been advocated for neck rejuvenation. These include botulinum toxin,47 injectable fillers,48,49 lasers50 and intense pulse light.51 Although these alternatives have a role in the treatment of facial aging either as ancillary or stand-alone procedures, they do not exert the same impact on facial aging that is seen with face/necklift surgery.

Feb 21, 2016 | Posted by in General Surgery | Comments Off on Neck rejuvenation
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