TITLE: THE AGING NECK
SOURCE: Grand Rounds, Dept of Otolaryngology UTMB
DATE: October 8, 1997
RESIDENT: Carl Schreiner, MD
FACULTY PHYSICIAN: Byron Bailey, MD
SERIES EDITOR: Francis B. Quinn, Jr. MD
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ANATOMY and AESTHETICS
The ideal youthful profile shows a strong mandible that separates itself from the neck by casting a shadow along its inferior border. The cervicomental angle should be 90 degrees or less with the hyoid at the apex of the angle, at or above the plane of the jaw. The thyroid notch should be visible as a gentle indentation and there should be essentially no horizontal rhytids. On anterior view, the mandible should demarcate the face from the neck and cast a shadow that hides the submandibular glands. The anterior border of the sternocleidomastoid muscle should be visible extending inferiorly, creating a small depression in the suprasternal notch. When considering cosmetic surgery of the neck, significant anatomic structures include the skin and subcutaneous tissues, chin, submental fat pad, hyoid and the platysma. It is also important to consider the lower third of the face and its associated musculature.
The superficial musculoaponeurotic system (SMAS) is a fibromuscular layer that encompasses and distributes force among the facial mimetic muscles. Superiorly, the SMAS is continuous with the galea and it incorporates the superficial temporal fascia and may become dehiscent over the zygomatic arch. Dissection is avoided in this area due to potential injury to the frontal branch of the facial nerve. In the parotid region, the SMAS is located superficial to and is distinct from the parotid fascia and peripherally, the branches of the facial nerve exit deep to the SMAS. The SMAS envelopes the facial muscles, particularly the zygomaticus major, anteriorly and has attachment to muscles in the perioral, nasolabial and periorbital areas. Inferiorly, the SMAS is continuous with the platysma muscle.
Understanding the anatomy of the platysma muscle is of paramount importance in cosmetic surgery of the neck and deserves special consideration. The platysma is the vestigial remnant of the panniculous carnosus of animals (which allows the horse to flick a fly off its back) and comes from the Greek work "plate" It is a quadrangular sheet of muscle which originates on the fascia of the pectoralis major muscle and ascends to three main points of insertion. The most anterior fibers decussate the the midline at variable levels below the chin and insert into the mentum. The central fibers insert into the body of the mandible and the more posterior fibers turn anteriorly and blend closely with the fibers of the risorius muscle. The platysma is innervated by the cervical branch of the facial nerve. The main lower branch exits the parotid and enters the deep surface of the platysma. The upper twigs of the cervical branch and lower twigs of the marginal branch intermingle before the marginal nerve passes on to supply the depressor anguli oris and risorius.
Based on anatomical considerations of the platysma muscle, Vistness derived several basic anatomic principles, including:
DIAGNOSIS and CLASSIFICATION of the AGING NECK
Surgical correction of the aging neck requires precise diagnosis of the pathologic anatomy causing the cosmetic deformity. Factors such as age, skin quality, fat deposition, muscle anatomy, and skeletal support all influence the surgical plan. In 1980, Dedo proposed a classification system of the neck based on anatomic layers.
A Class I neck is an essentially normal younger patient with a well defined mental angle, little fat, and good skin and platysma tone.
Class II patients show laxity of the cervical skin without significant fat deposition or muscle pathology. The skin must be redraped so wide undermining is required but a submental incision is usually not needed. A standard rhytidectomy with plication of the SMAS-platysma complex is usually all that is required.
Class III patients have a pathologic layer of subcutaneous fat, which is either genetic or acquired and liposuction is usually required to improve the cervical contour.
Class IV patients have varying degrees of platysma pathology, which must be diagnosed by voluntary facial grimacing preoperatively. This is usually evident as anterior cervical cording, but it may be difficult to asses the platysma due to fat accumulation. These patients require some form of surgical manipulation of the platysma.
Class V patients have retrognathia that contributes to their neck pathology and may require chin augmentation or mandibular osteotomies.
Class VI patients have an abnormal hyoid position. The hyoid is either too low or the mandible-to-hyoid distance is too low, limiting the effect of submental surgery. Patients with abnormally low hyoids (normal is at C4) need to be counseled preoperatively because there are currently no effective procedures to elevate the hyoid and their surgical results will likely be less than optimal.
The ideal candidate for cosmetic surgery of the neck is a nonsmoker strong bony landmarks, a normally positioned hyoid, good skin elasticity and realistic expectations. A thorough history and physical should be negative for a prior history of facial palsy, bleeding disorders and a history of NSAID use. Obviously not all patients will fit this profile but a systematic approach to the work up can prevent the often devastating consequences of a serious complication from a cosmetic procedure. Smokers should be approached with caution and strongly urged to quit before considering surgery. Preoperative asymmetries should be diligently sought after and demonstrated to the patient. Preoperative photographs should include the standard anterior, oblique and profile views along with views while smiling or grimacing to asses the platysma.
SURGICAL MANAGEMENT of the AGING NECK
Rhytidectomy is the cornerstone operation for the aging neck and face and has been well described in a prior grand rounds. This operation is effective for Class I and II patients whose primary problem is skin redundancy, whereas patients with more advanced neck pathology will often require adjunctive procedures, described in more detail later.
The procedure is begun preoperatively by marking the nasolabial folds, jowl lines, and platysmal bands in the upright position. The temporal incision is fashioned to preserve the temporal hair tuft and the incision is extended inferiorly along the preauricular crease and into the postauricular hairline. Flap elevation in performed in a subcutaneous plane with care to avoid injury to the great auricular nerve posteriorly. In smokers or patients with diabetes, the short flap technique is safer and dissection anteriorly is performed three to four cm and five to seven cm into the neck. Liposuction cannulas without suction may be used to assist flap elevation by creating multiple tunnels in a fanlike distribution. The liposuction tunnels will allow mobility of the flap without compromising vascularity. In nonsmokers, the long flap technique can be used, which involves elevation anteriorly to the parotid edge and dissection into the neck is continued until it is continuous with the submental incision. If dissection over the zygomatic arch is planned, this must be done in a subfollicular plane to prevent injury to the frontal nerve. After flap elevation, the SMAS layer is suspended by either plication or imbrication. Plication involves the placement of sutures that fold the SMAS over on itself, whereas imbrication involves cutting and resuturing, which is often considered an added step with no proven benefit. The redundant skin is judiciously trimmed, with special attention to the lobule to avoid the "pixie" ear deformity, closed tension-free and a pressure dressing is placed. The use of drains is somewhat controversial but are usually avoided unless suboptimal hemostasis is encountered.
The deep plane facelift is a recent advance in rhytidectomy technique that deserves mentioning. Although it was specifically designed to address the nasolabial fold area, it also may have added benefit to the submental area. In the deep plane facelift, after flap elevation, the SMAS is incised in a vertical fashion from the zygomatic arch down to below the angle of the mandible. The SMAS is then elevated from the underlying parotid fascia and subplatysmal dissection inferiorly is continued into the neck to the level of the thyroid cartilage. Anterior dissection over the buccal fat pad is continued to the insertion of the SMAS onto the nasolabial fold. The SMAS is then advanced and fixed in a superior direction, which creates a sling effect in the submental area. Careful blunt dissection is continued over the mandible. The advantage of this technique in the neck is that it creates a two-layer advancement flap which allows better lifting vectors on the submental area. Owsley, in his study of 460 patients, feels this often corrects submental deformities without a submental incision. The potential disadvantage is that deeper dissection may lead to increased facial nerve injury.
Class III patients have excess fat accumulation in the submental area. Liposuction, with or without concomitant rhytidectomy has essentially replaced the earlier technique of direct excision, due to its ease and safety. The procedure is performed by marking the first submental crease on the patient while in the sitting position. If direct platysmal manipulation is planned, the incision is placed more posteriorly. The limits for liposuction are the inferior border of the mandible superiorly, the sternocleidomastoid posteriorly and usually the cricoid inferiorly. After incising the skin, liposuction cannulas are passed in short strokes in a fan shaped pattern in the subcutaneous plane with care to avoid penetrating deep to the platysma.
The two most common complications encountered in submental liposuction are submental depression and anterior platysmal banding. Submental depression results from overaggressive liposuction in the submental area or inadequate "feathering out" of the submental fat area. To reduce the chance of dermal scarring and subsequent retraction, the opening of the suction cannulas should never be directed towards the skin. If the skin is allowed to pucker into the cannula, bands of fibrous tissue have been shown to produce pseudocords that can mimic platysmal banding. In 301 patients, Kamer and Minoli found a 6.6% incidence of postoperative anterior platysmal banding. All the patients that required reoperation were noted to have nondecussation of the platysma. Redundant skin and mild preoperative banding were associated with a higher incidence of banding but hyoid position did not seem to be an important factor. Obese patients are particularly problematic because the fat accumulation may mask the undecussated platysma and liposuction will only accentuate anterior banding.
Submental liposuction has shown clear benefits when used in conjunction with a facelift, but its role as an isolated procedure is still unclear. In general, the skin of the younger patient (usually less than 40) with good elasticity may tighten in the submental area following liposuction and rhytidectomy may not be required, but most older patients will encounter a certain amount of permanent redundancy that can only be addressed by rhytidectomy.
In Class IV patients without any substantial subcutaneous fat or in patients who are noted to have platysmal deformities, the platysma must be surgically addressed. Sharp dissection under direct visualization directly superficial to the platysma. Some feel it is important to leave a thin layer of subcutaneous fat attached to the skin flap to prevent scarring of the skin to the underlying platysma. The anterior border of the platysma is a key landmark because the tendency is to develop a plane deep to the platysma, risking injury to the marginal nerve. Elevation is continued inferiorly to the level of the thyroid cartilage and the skin above the incision may also be elevated anteriorly to allow placement of a chin implant if needed. Multiple procedures for addressing the midline platysma have been described but many involve excision of an oval 2 to 3 cm area of muscle and midline plication with tacking to the periosteum anteriorly. Simple midline reaproximation of the anterior border of the platysma is generally felt not to result in the same results as muscle excision and imbrication can result in midline neck fullness.
Some surgeons advocate excising a wedge or partially transecting the anterior border of the platysma to accentuate the cervicomental contour. Dedo feels this may masculinize the female neck by exposing the thyroid cartilage or it may contribute to ptosis of the submandibular glands. Submentoplasty, as opposed to wedge resection of the platysma restores the normal anatomic relationship of the platysma by fixing it to the mandible without weakening its "sling" effect in the neck.
Direct Skin Excision
There is a small group of patients who may benefit from direct excision of submental skin and subcutaneous tissue. These patients suffer from the so called "turkey gobbler" deformity . The obvious disadvantage of this technique is the submental scar and Biggs and Koplin state this point should probably be overemphasized to the patient preoperatively. Because the incision is in a hair-bearing area in males, men usually are more tolerant of this technique. This technique is not recommended for jowls or prominent platysmal bands.
In approaching the problem of the Class III neck, it is important to understand the underlying pathology is not just skin redundancy. Prominent nondecussated platysmal borders are often an adjunctive problem and must be addressed separately. Excessive supraplatysmal fat must also be separately addressed if encountered.
The amount of skin redundancy is first estimated by grasping the submandibular skin with the patient in the upright position. An ellipse of skin for excision is fashioned and may be modified in a variety of Z-plasty or A-T techniques. Dmytryshyn describes a technique that combines a Z-plasty of the platysma with a T-Z plasty resection of the overlying skin. He limits this operation to males, many of whom have already had a previous rhytidectomy and do not with to undergo rhytidectomy revision surgery.
The following summarizes an excellent article by Baker, "Complications of Cervicofacial Rhytidectomy" and includes complications of direct submental approaches s well:
Hematomas are the most common and troublesome complication of rhytidectomy, with an estimated incidence of about 15%. Most are small (<20cc) and may not be detected until the edema resolves. These may be aspirated between days 7-14, when the collection liquefies. After about two weeks, the clot becomes organized and the overlying skin may pucker or present as a contour deformity. This may require intralesional steroid injections but beware of atrophy at the injection site. Major hematomas occur in about 4% of cases and males appear to have a higher incidence than females. Excessive postoperative pain must be kept in mind as an indicator of hematoma formation. Preliminary reports with the newer facelift techniques do not sow a higher incidence of hematoma formation.
Facial nerve injury
Potential causes of facial nerve injury as reviewed by Castanares in rhytidectomy include, preoperative Bells palsy, electrocoagulation in the temporal region, local injection, deep plication sutures, excessive traction or crushing, transection of nerve during dissection deep to the platysma and hematoma formation. A careful history, looking for a previous facial palsy and careful documentation of preoperative asymmetries are essential. Baker feels that the newer rhytidectomy techniques will likely show a higher incidence of facial nerve injury, although preliminary reports have no confirmed this observation. The frontal nerve is the most commonly injured branch, usually injured as it crosses over the zygomatic arch. The marginal nerve is at risk with deep dissection below the platysma and may be injures with direct submental techniques.
Great auricular nerve injury
This nerve is the most superficial and most commonly injured nerve during rhytidectomy. Injury usually occurs when dissection is too deep over the sternocleidomastoid, where the nerve is intimately involved with the dermis.
The incidence of skin necrosis is estimated to be between 1 - 3% and smokers have a 12 fold higher incidence of skin slough. Vasular compromise can occur through hematoma formation, excessively superficial dissection, excessive trauma or wound tension, previous surgery, or infection. Smokers should be strongly encouraged to stop smoking for 2 weeks before and 2 weeks after surgery and some surgeons even monitor nicotine levels if there is a suspicion of noncompliance.
Submental contour deformities
As stated earlier, a submental depression can occur with overaggressive liposuction of the submental area. This can create a relative overabundance of fat along the mandible and jowl area, creating the so called "cobra deformity". Liposuction of the submental area can also either create a "pseudoband" effects from fibrous attachments to the dermis or it may unmask a previously undiagnosed platysmal nondecussation which may not become evident until the edema resolves. If excessive defatting of the neck is performed in a patient with a round face, a "lollipop" appearance may result.
Submandibular gland ptosis
If a SMAS rhytidectomy is performed in a patient with a nondecussated anterior platysma, the change in vector forces will adversely effect the "sling" action of the platysma on the submandibular glands. If the anterior platysma is not addressed at the same time, ptosis of the glands may be evident postoperatively. Various procedures to tack up the submandibular gland have been tried but usually do not last over time and resection of the glands is risky due to limited exposure.
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