10 Techniques for the Difficult Neck
The ideal neck consists of a clean cervicomandibular line, a defined breakpoint near the level of the hyoid bone, a well-positioned chin, and a submandibular gland that is not visible in the digastric triangle ( Fig. 10.1 ). Specifically, the cervicomental angle (CMA) or breakpoint of the neck should be ~90 degrees with the hyoid bone at the apex of the angle. Ideally the thyroid notch is perceived as a subtle protrusion below the level of the breakpoint, without any noticeable horizontal rhytids in the neck.
A working knowledge of the fibromuscular layers of the neck is necessary to understand the surgical concepts presented in this chapter. The superficial musculoaponeurotic system (SMAS) invests the face and neck from the galea (with which it is continuous), through and around the superficial muscles of facial expression in the midface and lower face, and down into the neck, where the SMAS is continuous with the platysma muscle. The platysma muscle itself, the name of which comes from the Greek word for “plate,” is a quadrangular sheet of muscle originating from the fascia of the pectoralis major muscle inferiorly and ascending superiorly to attach to the mandible at the level of the mentum medially, to the body of the mandible and to the SMAS lateral to the midline of the mandible, and to sweep laterally up to and around the risorius muscle and related structures ( Fig. 10.2 ).
On the basis of the anatomy of the platysma muscle, Vistness1 proposed several anatomical observations that he felt had surgical consequences. These are listed here in Vistness’s own words, with commentary about each:
“ The platysma is intimately attached to the skin by fibrous septa, which must be completely separated to mobilize the skin independently of the platysma muscle. Because of this relationship, redundancy of the skin usually implies redundancy of the platysma muscle skin of the neck and platysma separately to improve laxity in the neck (author’s interpretation). The author will show that this is indeed not true for patients without medial platysmal banding, significant submental fat, and/or an anteriorly located hyoid bone.
“ If the platysma is tightened by changing the direction of its fibers, the change in vector may forcibly affect other muscles.” The concern expressed in this is that the depressor anguli oris and/or risorius muscles exert functional pull on the lips during animation, which may be affected should the force vector of the platysma be changed appreciably or reoriented in an unnatural direction. The author has found that this can indeed be the case should the direction of platysmal pull laterally be other than at the typical breakpoint of the neck. Otherwise the author has not found this point to be clinically significant.
“ If the anterior fibers do not decussate, prominent vertical bands in the anterior neck may form. The submandibular fat pads and submandibular glands (SMG) will not be sup-ported well and may become ptotic, blunting the contour between face and neck. Treatment requires approximation of the medial borders of the platysma.” The author agrees that medial platysmal banding requires aggressive management of the medial platysmal border, a technique that will be reviewed later in this chapter; however, ptosis of the SMG is more commonly seen in patients with a weak chin with or without an anteriorly located hyoid bone. To reliably treat this problem one needs to consider more than simply tightening the medial border of the platysma.
“ Transection of the cervical branch of the facial nerve may have a detrimental affect on some people with a full smile should the platysma work in synergy with the depressor anguli oris.” The author agrees that transection of the cervical branch of the facial nerve is a poor surgical maneuver, but would add that full horizontal sectioning of the platysma from its lateral to its medial border is similarly a poor surgical choice. Anything that causes this muscle to atrophy over time will ultimately result in an unusual withered look to the neck, an appearance that is difficult to improve.
◆ Classification of the Aging Neck
When discussing correction of the aging neck it is helpful to attempt to classify necks into categories that relate to anatomical findings. Many factors would need to be taken into account to make this exercise useful, including patient age, skin quality, relative abundance and location of fat, chin position especially as it relates to the hyoid bone, and other skeletal and muscular anatomical findings. Dedo2 proposed a classification system of the neck based on anatomical layers (see Chapter 2). Dedo’s classification is useful but somewhat muddled in that most patients who present for rejuvenation of the neck fall into more than one of Dedo’s classifications. The author tends to think of these patients in terms of the degree of difficulty of treating their deformity. which relates directly to the surgical plan for their treatment. With this in mind, the author proposes the following revised classification system:
Class 1: Patients in this class require an easy surgical plan. They either have simple laxity of the skin and require lateral support of the SMAS–platysma complex via a short-flap approach or a lateral platysmal lift (should the surgeon deem this necessary), or they simply have excess submental fat but with good tone, and simply need recountouring of this submental fat ( Fig. 10.3 ). Should they need a chin implant in addition, this will not change the complexity of the approach to their treatment; a chin implant is added as needed and should be encouraged by the surgeon should the patient vacillate, since adequate anterior mandibular support will give better short- and long-term results.
Class 2: Patients in this category require a more aggressive surgical plan because of the presence of medial platysmal banding. Full release of the skin from the platysma will be needed, requiring a lateral and medial approach should significant medial platysmal banding present, or contouring of subplatysmal fat will be required; medial platysmal plication is mandatory in these patients. Should a chin implant be necessary, it is strongly recommended to the patient and inserted if permission is granted ( Fig. 10.4 ). The patient who does not acquiesce to a chin implant when it is needed should be advised that the short- and long-term results of their surgery will not be as gratifying as it would with an implant. Many patients in this category will also require inferior fixation of the platysma to the hyoid bone, with or without minimal resection or shortening of this part of the platysma, depending on the degree of banding and the strength of the chin. Many of these patients will require a degree of contouring of sub-mental fat. Lateral fixation of the platysma will always be needed, and may be the only step needed to obtain an excellent result should medial platysmal banding be minimal, the position of the hyoid bone adequate, and contouring of fat unnecessary.
Class 3: Patients in this category have anatomy that makes obtaining a satisfactory end result difficult if not impossible ( Fig. 10.5 ). These patients will invariably have a poorly located hyoid bone. Additionally, it has been the author’s experience that most patients with anteriorly located hyoid bones will have some degree of ptosis of the SMG. Patients with a good position of the hyoid bone but significant ptosis of the SMG are also in this group, although they are the exception rather than the rule. Many of the patients in this latter group have a weak chin, which is easily corrected with an appropriate chin implant. The approach to patients with significant SMG ptosis and/or a poorly located hyoid will be reviewed later in this chapter.