Rejuvenation of the Neck

INTRODUCTION

Rejuvenation of the neck is an important aspect of the treatment of the aging face. The effects of aging are often prominently displayed in the neck. Recurrence of laxity in the neck is also a common complaint following facial rejuvenation procedures.

Common neck deformities for which surgical rejuvenation is performed include skin laxity from loss of tone of the dermal elastic fibers and loss of ligamentous support, platysma muscle banding, increased deposition of adipose tissue, prominent digastric muscles, and protrusion of the submandibular glands. Rejuvenation of the neck can be accomplished with a comprehensive cervicofacial rhytidectomy procedure or in isolation using a variety of techniques.

HISTORY

Paramount to a successful rejuvenation of the neck is to first determine what the patient wants. Often times, patients who need neck rejuvenation may not fully understand that they need a surgery of the neck. Conversely, many patients focus purely on their aging neck. Assessing patient expectations and deciding on whether expectations are achievable takes time, and a detailed history is critical. From a medical standpoint, questions pertaining to any prior surgery of the neck are important as scars will affect any neck surgery being planned. Inquiry into thyroid abnormalities is to be made as patients may expand upon either swallowing or respiratory symptoms that may be exacerbated with a tightened neck postoperatively. Patients with any history of dysphagia, globus sensation, reflux, and/or upper respiratory symptoms including obstructive sleep apnea need medical clearance for an elective neck lift. Questions should be posed to assess for any psychological concerns with the sensation of having a tighter neck postoperatively as expectations and tolerance for postoperative symptoms will be met. After a medically focused history taking, a psychological assessment focusing on the aesthetic expectations of a neck lift is important. Balancing what is achievable and what is impossible can only be done with a detailed discussion with the patient. Sometimes a repeat consultation is needed to fully inform the patient of what to expect. However, many repeat visits or unrealistic expectations by some patients may be a sign to avoid neck surgery altogether.

PHYSICAL EXAMINATION

When discussing the effects of aging on the neck, an understanding of the anatomic structures is key. Aesthetic concerns in the neck may involve one or more of these structures, and treatment of the aging or ptotic neck must be tailored to address these specific issues.

A well-defined cervicomental angle (CMA) is the hallmark of a youthful-appearing neck, and its reestablishment is often a principal goal in rejuvenation surgery of the neck. The CMA is defined by the intersection of a horizontal line drawn through the menton and an oblique line following the anterior border of the neck. The ideal angle is traditionally considered to lie within the range of 105 and 120 degrees.

The CMA has been described as being most significantly defined by the position of the hyoid bone in relation to the mentum. The hyoid typically rests at the level of the fourth cervical vertebra. Posterosuperior positioning of the hyoid contributes to a well-defined CMA, while anteroinferior displacement causes a more obtuse angle and is much more challenging to address surgically.

The platysma muscle can form undesirable, prominent bands in the aging neck. The bands correspond to pleats of the medial platysma body rather than the muscle edges themselves, as the edges are tightly adherent to the deep cervical fascia at the level of the hyoid bone.

The platysma originates in the subcutaneous tissue of the infra- and supraclavicular regions and inserts at the base of the mandible and orbicularis oris, as well as subcutaneously in the cheek and lower lip. The muscle is bilateral and obliquely oriented, joining in the midline with interdigitating fibers in the mentum. Its actions include depression of the lower lip and face, as well as forced opening of the mandible. Platysma muscle bands are thought to originate from the development of laxity in the neck skin, superficial cervical fascia, and the platysma-retaining ligaments.

Platysma bands can be categorized as static or dynamic. Static bands are the commonly bothersome variety, and lie in a paramedian vertical orientation corresponding to the medial platysma muscle. These muscle bands exist at rest and contribute to the blunting of the CMA. Dynamic muscle bands, on the other hand, present during active platysma muscle contraction and may lie along the central portions of the muscle as well as along its medial aspect. Botox has been used for dynamic bands to decrease platysma band prominence by eliminating baseline tone and causing atrophy through repeated treatments.

Excessive cervical adipose tissue can be separated into subcutaneous and subplatysmal planes. Cadaver studies have described three compartments in the subplatysmal plane: central, medial, and lateral. The central compartment is a typical yellow color, while the medial and lateral compartments are paler, similar to buccal fat.

The digastric muscle is composed of two embryologically distinct anterior and posterior bellies joined by an intermediate tendon. The anterior belly is innervated by the mylohyoid nerve from the mandibular division (V3) of the trigeminal nerve (cranial nerve V). It originates at the symphysis menti of the mandible. The posterior belly originates in the digastric groove of the mastoid bone and is innervated by the digastric branch of the facial nerve (cranial nerve VII). The intermediate tendon penetrates the stylohyoid muscle and passes through a fibrous sheath that is attached to the body and greater cornu of the hyoid bone.

The paired submandibular glands provide 70% of salivary volume and are divided into superficial and deep lobes by the mylohyoid muscle. Each gland rests within an impression on the lingual surface of the mandibular body called the submandibular fossa, just below the mylohyoid line, the site of origin of the mylohyoid muscle. Secretions are passed through Wharton’s duct, which runs superior to the mylohyoid muscle and out of the sublingual caruncles located on either side of the lingual frenulum in the anterior floor of mouth. The investing layer of deep cervical fascia envelops the gland. The marginal mandibular branch of the facial nerve runs on the posterior surface of the platysma muscle, just superficial to the facial vein and submandibular gland.

Dedo described a commonly used classification to characterize the nature of neck abnormalities. Each class presents a distinct anatomic contribution to the neck deformity that must be addressed with appropriate surgical techniques.

Class I: Normal, youthful neck with a well-defined CMA, minimal adipose tissue, and good skin and platysma tone

Class II: Laxity of the cervical skin only

Class III: Abundance of subcutaneous adipose tissue

Class IV: Platysma muscle bands

Class V: Retrognathia

Class VI: Low-lying hyoid

While these classes describe different anatomical problems, many of these problems can coexist. Other problems that are not described in this classification system include prominent digastric muscles, submandibular glands, and subplatysmal fat.

PREOPERATIVE PLANNING

Prior to operating on the aging or ptotic neck, the surgeon must assess the various anatomic structures in order to establish the appropriate surgical plan. For many surgeons, the diagnostic process is important in the decision to perform an open neck procedure. If the soft tissues of the neck are soft and mobile, one can often manipulate the platysma and subcutaneous adipose tissue alone. If the neck is firm or other specific anatomic features are abnormally prominent, more extensive procedures may be indicated.

In order to distinguish between excessive subcutaneous and subplatysmal adipose tissue, the surgeon may grasp the superficial soft tissue of the neck between thumb and forefinger and ask the patient to swallow. Palpation of subcutaneous adipose tissue alone is soft and does not move significantly with swallowing. Abundance of subplatysmal adipose tissue and/or prominent digastric muscles manifests as firmness in the neck with more movement during swallowing. The firmer nature of the subplatysmal adipose tissue is due to the presence of fibrous bands in this plane, including the platysma-retaining ligaments. This also makes the removal of adipose tissue more difficult in the subplatysmal plane compared to the subcutaneous compartment.

A neck that is tight and resistant to manual upward pressure on physical examination is referred to as a “tension neck.” This type of neck may require an open procedure to address the deep ptotic structures.

The digastric muscles demonstrate a characteristic lump in the midline submental neck. Occasionally, they can become prominent postoperatively when uncovered by a neck defatting procedure if not diagnosed early and included in the surgical plan.

Prominent submandibular glands may be seen and palpated in the lateral neck. This bulge may be due to ptosis, an enlarged gland, or an insufficient bony fossa. Occasionally, a bulge is noted following a neck lift procedure when it was not initially present. Removal of superficial adipose tissue may be the culprit, but when lipectomy has not been performed, the development of a submandibular bulge may be due to its traction into a more prominent position from adhesions of its capsule to the undersurface of the pulled platysma.

High-frequency ultrasonic images have been used to elucidate various pathologies of the aging submental neck (Fig. 13.1). The superficial cervical fascia that envelops the platysma strongly reflects sound waves, clearly delineating the boundaries of the subcutaneous and subplatysmal adipose tissue spaces. These planes can therefore be independently measured to evaluate their contributions to the full neck. The size of the underlying digastric muscles can also be assessed. When liposuction or direct excision lipectomy is performed in the fatty neck, many of the above problems can become apparent that were not identified preoperatively, and ultrasonic evaluation can aid in accurate diagnosis.

SURGICAL TECHNIQUES

Many techniques for rejuvination of the neck have been developed over the past four decades. These techniques often share the focus of correcting the obtuse CMA and platysma muscle bands. The method used is based on both the anatomic abnormality being addressed as well as the surgeon’s preference.

Lipoplasty

When indicated, liposuction or direct excision can be used to address large adipose tissue deposits. Care is taken to avoid skeletonizing the underlying structures, and 4 to 5 mm of subcutaneous adipose tissue should be left on the skin flap to allow adequate coverage. Potential complications of overaggressive removal of adipose tissue in the neck include the development of irregular contour, a hollow neck appearance, skin necrosis, and unmasked prominence of underlying structures such as the submandibular gland and the larynx.

When performing liposuction, cannulas are introduced through submental and periauricular incisions. This bidirectional approach ensures thorough and even removal of adipose tissue. Subcutaneous tunnels are created through multiple repeated passes of the suction cannula resulting in both mechanical avulsion and removal of adipose tissue, as well as contraction of the subcutaneous tissues during the healing process. Suctioning aggressively on the platysma muscle is avoided to ensure that the muscle remains intact.

The elastic skin envelope then contracts over the scarring underlying tissues. It has been suggested that skin retraction may be enhanced when liposuction is performed in a superficial plane near the undersurface of the dermis.

FIGURE 13.1 Ultrasound results. Frontal views, lateral views, and submental ultrasound scans of the 10 study patients. Note pseudoherniation of the subplatysmal fat in patients 1, 5, 7, 8, and 10 and the relative digastric hypertrophy in patient 3. Arrows indicate platysma muscle; D, digastric muscle; M, mylohyoid muscle. (Reprinted from “The Utility of Ultrasound in the Evaluation of Submental Fullness in Aging Necks,” by Mashkevich G, Wang J, JAMA Facial Plastic Surgery, vol. 11(4), pp. 240-245. © 2009 by the American Medical Association.)

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