Therefore a patient listed as Type IV AB would be a patient who requires a facelift with submentoplasty, chin implant along with submandibular gland resection (Fig. 24.8).

The goals in rejuvenation of the aging neck are:

1.To restore a more youthful cervicomental angle

2.To redrape and tighten the skin within the cervical/ submental region

3.To eliminate or decrease platysmal banding

4.To correct any deficiency in chin projection

5.To correct or improve skin laxity

6.To enhance the length and sharpness of the mandibular border

7.To soften or eliminate any contour irregularities associated with aging and fatty changes

24.4 Anatomy

When performing submentoplasty or submental liposuction one must have an understanding of some key anatomic features of the neck in order to avoid complications and ensure an aesthetic outcome. The platysma (Greek for flat object or plate) is a vestigial muscle that originates in the fascia of the pectoralis major and inserts above the inferior border of the mandible. It is innervated by the lateral cervical nerves. Cadaver dissections by Cardoso de Castro [17] have demonstrated that there is a decussation in the midline in 75% of people (Fig. 24.9).

With age, fat can accumulate above the platysma and below. The fat above the platysma is easily removed

Fig. 24.8 (Left) Preoperative 57-year-old. (Right) Three months following a facelift with submentoplasty, chin implant and partial submandibular gland (SMG) resection. The patient has a Type IV AB neck. Type IV necks require both a facelift and submentoplasty because of both extreme skin laxity, jowling and platysmal laxity. Subtype A indicates a weak chin and B implies SMG excess

A ‘V’ shaped fullness in the SMG region is usually indicative of glandular hypertrophy or ptosis that can be evaluated during the submentoplasty

Fig. 24.9 (a) Type I: 75% of patients have limited decussation of the platysma extending 2–3 cm below the mandibular border. (b) Type II: 15% of patients demonstrate decussation of the plat-

ysma from the mandibular border to the thyroid cartilage. (c) Type III: 10% of patients demonstrate no decussation of the platysma

with liposuction. Subplatysmal fat is more fibrous and is slightly whiter in color. In the cheek area the superficial musculoaponeurotic system (SMAS) is its equivalent. This fat is more efficiently removed via sharp or electrocautery dissection. Below the subplatysmal fat the anterior digastric and mylohyoid muscles are visible. Within the subplatysmal space one will also encounter the anterior jugular veins. When dissecting under the platysma one must be vigilant to avoid these veins as they may cause troublesome bleeding. The posterior border of the platysma often runs parallel and just in front of the external jugular vein. At this location the external jugular vein crosses the sternocleidomastoid muscle as the vein moves toward the central portion of the clavicle. The midline of the hyoid bone is the landmark used prior to making a back-cut to mobilize the platysma. The hyoid also marks the inferior limit of platysmal resection in most cases. Submandibular glands are located underneath a layer of cervical fascia in the subplatysmal space lateral to the lateral border of the anterior digastric muscle. A more detailed description of this anatomy will be provided in the section on submandibular gland resection.

An important nerve that is most at risk for injury during submentoplasty or liposuction of the neck is the marginal mandibular nerve branch of the facial nerve. Injury to this nerve results in weakness of the ipsilateral lower lip depressor muscles (depressor labii inferioris, mentalis, and depressor anguli oris). The nerve leaves the anteroinferior edge of the parotid gland and runs deep to the platysma as either one main nerve trunk (40%) or as two branches (50%) or as three to four branches (10%) and then travels either above or below the mandible. Occasionally, the nerve runs 1–2 cm below the mandibular border shortly after exiting the parotid but proceeds back above the border of the mandible at the antegonial notch as it crosses over the facial artery. Baker and Conley wrote that in their clinical experience the nerve is usually 1–2 cm below the lower mandibular border but can be as much as 3–4 cm below it [18]. Dingman and Grabb noted in their cadaver series that posterior to the facial artery the nerve passed above the inferior mandibular border in 81% of dissections. Anterior to the facial artery all of the marginal mandibular nerve branches innervating the mouth depressors passed above the lower border of the mandible [19]. Approximately 2 cm from the lateral corner of the mouth the nerve becomes more superficial and enters the undersurface of the depressors [20, 21, 22].

24.5 Liposuction

Upon completion of the patient’s aesthetic analysis a decision can be made to proceed with liposuction alone or in combination with submentoplasty or with submentoplasty and rhytidectomy. The most suitable patient for isolated submental and cervical liposuction has no platysmal banding, (at rest or with animation) minimal subplatysmal fat, no jowling and excellent skin tone. In addition, the ideal patient will have a good hyoid/thyroid position and a lack of submandibular gland ptosis.

In the past, surgeons used large spatulated cannulas and sought to remove as much fat as possible. This often lead to pleasing early results but in some cases significant scarring, contour irregularities, and even a skeletonized look resulted with the passage of time. The authors approach is to use microcannulas of approximately 2–3 mm in size. These smaller cannulas facilitate the sculpting process and decrease the likelihood of contour irregularities. Our goal is to leave a uniform 4–5 mm of fat behind.

Recently laser lipolysis using YAG (yttrium– aluminum–garnet) technology has become popular. The technology continues to evolve with different manufacturers claiming the benefits of different wavelengths. The touted benefits include better skin retraction, less bleeding and bruising, and a shorter recovery time.

The goal of this technique is to use laser energy to emulsify the fat prior to suctioning while heating the dermis which also may aid in skin contraction. The authors have used both 1,320 and 1,064 nm wavelengths and feel that there may be some benefit in small areas such as the neck. Much more needs to be learned about laser lipolysis. Specifically, what is the optimal wave length and ideal amount of energy delivery needed for collagen tightening while at the same time avoiding injury? The technology is further limited by its substantial cost. Presently, we look forward to the publication of definitive studies. Essentially the most important thing required to achieve an excellent neck contouring result in the Type I patient is superb skills with microcannular liposuction and the ability to choose the correct patient.

24.6 Tumescent Anesthesia

Tumescent anesthesia was developed by Cosmetic Dermatologist Jeffrey Klein in 1985. Essentially Klein demonstrated that when dilute lidocaine solution is

combined with Epinephrine; liposuction can be safely performed under local anesthesia. Since that time Tumescent anesthesia has been incorporated into virtually every aspect of cosmetic surgery. The power of the technique is that it is safe, while at the same time providing profound long lasting anesthesia with a marked reduction in blood loss. This fact makes tumescent anesthesia useful with general anesthesia as well as with sedation or as a stand-alone technique. A review of the Physicians’ Desk Reference will show that the maximum safe dose of lidocaine is 7 mg/kg when used with epinephrine. This is actually an extrapolated dose limit that was established by a letter to the Food and Drug Administration in 1948 from Astra Pharmaceuticals. The letter stated that the safe dose for lidocaine “was probably the same as that for procainamide” [22].

Exhaustive and well-executed studies by Klein have demonstrated that the maximum safe dose for using dilute lidocaine with liposuction is 35 mg/kg [23]. Peak lidocaine levels occur 12–24 h after administration for body liposuction but may occur as early as 3–4 h after facial tumescent anesthesia because of the increased blood flow in the face. In a study of 20 patients receiving approximately 50 mg/kg, peak levels were less than 3.5 Pg/ml. (The toxic threshold for lidocaine is 5 Pg/ml) With the tumescent technique, studies have also shown that up to 4,000 ml of fat can be removed safely in one session [24]. When larger volumes of fat are removed the physiologic insult increases exponentially. Large volume liposuction is associated with potentially massive intravascular volume shifts and an increase in cardiac complications, deep venous thrombosis, and pulmonary embolism. Neck and facial liposuction is considered small volume liposuction and usually less than 100 ml of fat is removed.

Lidocaine’s main effects are due to decreased conductance through the sodium channels which results in neural blockade and an antiarrhythmic effect. Lidocaine is hepatically metabolized and renally excreted, 10% of which is unchanged. Therefore, one should beware of the patient with undiagnosed liver disease such as a case of occult cirrhosis.

There are many drugs that may affect lidocaine metabolism. Any drug that is metabolized by the cytochrome P450 3A4 (CYP3A4) system can increase the likelihood of lidocaine toxicity. The most common drugs that will affect lidocaine degradation include the proton pump inhibitors, benzodiazepines (lorazepam is an exception), serotonin reuptake inhibitors (Zoloft, Prozac, Lexapro, Celexa, Paxil, etc.), macrolide

antibiotics and calcium channel blockers. Ciprofloxacin, Beta blockers and protease inhibitors may also increase the likelihood of toxicity [25]. When one or more of these drugs is being used by a patient in whom we are performing liposuction on multiple body areas, our approach is to stop the drug 1–2 weeks prior to surgery.

The risk of lidocaine toxicity with cervical and submental liposuction should obviously be low. However, when multiple procedures are being performed with tumescent anesthesia it is important to remember that lidocaine levels may not peak until 12 h later. The authors routinely check their patients on the evening of surgery and are cognizant of the fact that this is when lidocaine toxicity symptoms may manifest. The symptoms of lidocaine toxicity include: nervousness, dysarthria, tinnitus, metallic taste, apprehension, dizziness, double vision, nausea, and vomiting. This can be followed by respiratory depression and seizures. Late manifestations include cardiac toxicity with bradycardia, hypotension, depressed contractility, cardiac conduction, and finally, cardiac collapse.

Epinephrine is an important component of tumescent anesthesia in that its alpha-1 agonist activity causes profound vasoconstriction. This markedly diminishes blood loss and bruising. The epinephrine also decreases the systemic absorption of lidocaine thereby reducing systemic toxicity [26]. A known side effect of epinephrine is tachyarrhythmia secondary to beta-1 agonist activity. In our experience, this is rarely seen in the doses used for submental liposuction. It has been shown that premedicating with the centrally acting alpha 2 agonist Clonidine can reduce the frequency of tachyarrhythmia’s [27].

When one is performing liposuction under sedation only, it is important to add bicarbonate to the tumescent solution. Shifting the pH in an alkaline direction will markedly reduce the pain and discomfort that the patient experiences when the relatively acidic lidocaine is injected. The goal is to obtain a bicarbonate concentration of 10 meq/l [28]. For ease of use, an 8.4% solution of sodium bicarbonate is equivalent to 1 meq/ml.

24.7 Liposuction Technique

While standing or sitting the patient is marked with an indelible marker. This is an important step because once tumescent anesthesia has been infused and the

patient is in the supine position the patients original landmarks will be obliterated. During marking, it is helpful to outline the mandibular border, the posterior neck margins and areas jowling. If an area does not need suctioning then it is marked in red. If a chin implant is to be performed, this area is outlined on the mandible and the location of the skin incision marked. Digital pictures are then taken in the AP, oblique, and lateral positions (Fig. 24.10). These photos are projected in the operating room for reference during the procedure. With the patient asleep, the face and neck are sterilely prepped and tumescent anesthesia is infused. The author’s preferred tumescent solution for work in the face and neck area is: 30 ml of 2% lidocaine with 1.5 ml of 1:1,000 epinephrine in 500 ml of normal saline.

A Wells Johnson (T) pump or an HK Klein (T) pump is used to administer the tumescent solution to the submental region via a 22 gauge spinal needle. A total of 150–200 ml of tumescent solution is infused. The needle enters the skin at three sites. Just under each ear lobe and under the chin. Care is taken to stay above the SMAS and the platysma and out of the external jugular vein. One should also endeavor to avoid a “peau d’orange” appearance of the skin on areas that may be undermined. There are scattered reports of skin sloughing after rhytidectomy that are attributed to infusing too much tumescent too superficially, although we have not seen this problem. The access sites will ultimately be enlarged with a number 11 blade to allow entrance of our microcannulas. These locations allow for efficient and safe liposuction of the neck from multiple directions. Post procedure these access sites are not readily visible. The location of these access sites can easily be incorporated into the incisions for

rhytidectomy, submentoplasty, and chin implantation. Following the infusion of tumescent anesthesia, the neck is the re-prepped and draped in a sterile fashion. Ideally, the surgeon should wait 15–20 min prior to initiating liposuction. This allows for maximal vasoconstriction and a slight detumescence of the tissue which facilitates the surgeon’s ability to evaluate tissue thickness.

The goal of Type I isolated liposuction of the neck is to restore a more youthful, neck jaw angle. Just as important as removing fat from the neck and the submentum is the sculpting of the mandibular border. To accomplish this one should minimize any fat removal from the body of the mandible and focus on enhancing its shadow by removing fat below this area along the length of the mandible. One must beware however that if too much fat is removed in this area, the underlying submandibular glands and digastric muscles may become visible. Once the tumescent access sites have been enlarged with a number 11 blade a microcannula is introduced into the subcutaneous plane. With the patients neck carefully hyperextended, suctioning is initiated with a back and forth motion (Fig. 24.11). Care is taken to avoid penetration of the platysmal. It is also important to understand where the cannulas suction orifices are located to avoid “rasping” the dermis. To avoid dermal damage with its resultant scarring one must focus on keeping the cannula openings toward the platysma. With each passage of the cannula the surgeon must be sure of which plane the tip of the cannula resides. The depth of the cannula and the amount of fat removed is controlled with the flat portion of the nonworking hand. With increasing pressure against the skin and subcutaneous tissue, the cannula will be more efficient in its fat removal and can be directed deeper.

Fig. 24.10 Preoperative markings for submentoplasty demonstrating boundaries such as the mandibular border in blue along with the level for a platysmal back-cut if desired. The location of the submandibular gland and maximum jowling is also noted

Area of resection

gland

Level of platysmal back cut