Nonsurgical Neck Contouring Using Deoxycholic Acid or Microfocused Ultrasound

Lawrence S. Bass

DEFINITION

Submental fullness is the result of excess fat contributing to a convex surface contour.
Skin laxity manifests as visible redundancy of skin.
Deoxycholic acid (DOCA) is a bile salt that destabilizes cell membranes and emulsifies fat. A synthetically prepared DOCA is Food and Drug Administration (FDA) approved for the reduction of submental fat and fullness.¹
Microfocused ultrasound (MFUS) is a technology that uses ultrasound to image the target tissues (diagnostic ultrasound) mated with therapeutic ultrasound that produces zones of coagulation. These zones are fractionated spots of coagulation at a predetermined depth under the skin. Sound energy is delivered in a beam that transits the skin at a low energy density converging at a predetermined depth under the skin by creating a high energy density zone of defined shape and size. A line of 25 fractional zones of coagulation is produced each time the device is fired.
Ultrasound transducers of different frequencies are selected for the desired depth of treatment. Total energy in each spot in the line can be varied on the device.

ANATOMY

The submental area is bounded by the inferior border of the mandible (mentum) anteriorly, the hyoid bone posteriorly, and the inferior border or the mandibular bodies laterally.
Fat in this area can be subcutaneous or subplatysmal.
Aging changes in the neck include visible skin laxity or redundancy, prominence of visible platysmal bands, and skin surface changes.
Laxity may manifest as a visible jowl, loss of jawline definition, and hanging festoons of skin in the neck independent of any platysmal banding.
Transverse rhytides; crepey, rough skin texture; and solar elastosis are surface aging changes that can be treated with MFUS.

PATIENT HISTORY AND PHYSICAL FINDINGS

Due to the focused nature of the results obtained with DOCA and MFUS, a detailed history of aesthetic issues and goals is essential to ensure that the correct therapies are selected.
Previous aesthetic therapies and surgeries should be carefully documented. Although these treatments are frequently performed in individuals who have previously undergone some form of treatment, safety and outcomes after extensive or multiply recurrent treatments have not been formally studied or reported at this time.
Examination should catalogue the location and magnitude of changes in each clinically pertinent tissue layer.
The degree and location of skin laxity in the jowl, jawline, and submental area are determined along with laxity changes inferior to the thyroid cartilage, which must be addressed separately.
Presence of visible excesses in subcutaneous fat in the jowl and submental and lateral neck areas should be recorded.
Platysmal diastasis is an important finding both for procedure selection and patient counseling. The distance of separation and vertical extent of separation should be noted.
Although it is not routinely possible to determine the amount of excess fat present in the subplatysmal plane on physical examination, this may limit the amount of improvement obtained with DOCA injection that addresses the subcutaneous plane only.

IMAGING

Radiologic and diagnostic studies are not customarily used.

SURGICAL MANAGEMENT

Excess fat in the neck, in the absence of skin redundancy, has traditionally been treated with suction-assisted lipectomy. Increasingly, energy-based devices have been mated with the liposuction procedure to amplify skin tightening or lifting in patients with mild laxity resulting from aging changes.
For more advanced aging changes with skin laxity in the jowl and neck area, surgical lifting procedures such as facialplasty, neck lift, and submentalplasty are the standard for providing the most complete correction, albeit with greater incisions, recovery time, and cost.
More recently, minimally invasive treatments utilizing sutures that suspend facial and neck tissues and stimulate neocollagenesis are occasionally utilized.

NONSURGICAL MANAGEMENT

DOCA injection is indicated for the treatment of subcutaneous fat in the submental area. Treatment of fat in the neck inferior to the mandible and anterior to the sternocleidomastoid muscle is also commonly performed.
Two to six treatments are required depending on the degree of excess fat. Each treatment has up to 50 injections of a fixed dose of medicine placed at a fixed distance apart.
The amount of fat present determines the number of treatments required. Retreatment is performed at interval of at least 1 month between treatments.
Although larger necks can be treated, the ideal patient has modest to moderate amounts of fat and is typically treated in two to three sessions of 20 injections each.
Treatment of jowl fat is specifically contraindicated due to concerns of injury to the marginal mandibular branch of the facial nerve. Theoretically, this may not be rational on an anatomic basis given the typical submandibular location of the nerve as it courses past the jowl area and due to the subplatysmal location of the nerve. But as of this writing, there is no published clinical experience demonstrating the safety or lack thereof for treatment of the jowl.
MFUS has a specific FDA indication for the noninvasive lifting of skin in the jowl and neck region. Surface features such as transverse neck rhytides and laxity below the level of the thyroid cartilage can also be addressed.
The ideal patient has good skin quality with only modest skin excess and is not substantially overweight.
A single treatment is performed to produce neocollagenesis and skin lifting over a 3- to 6-month period, although repeat treatments may be performed for more improvement if the patient is a responder.
The combination of DOCA injection and MFUS may provide a noninvasive means to correct many of the changes seen in the aging neck if they are mild to moderate in severity. There is currently no published literature reporting results using this combined approach.

Preoperative Planning

The size of the treatment area for DOCA injection must be determined so the amount of medicine needed can be calculated and the patient advised of treatment cost. The patient also should be advised of the likely number of treatments to provide a complete or near-complete correction.
Patient counseling about expected recovery after DOCA injections is essential to avoid unexpected disruption of work and social activities.
MFUS treatment planning involves assessment of the area requiring treatment at each depth and the amount of treatment at each depth (number of lines to be placed). Although there is a theoretical standard 3-mm advancement of the transducer between lines, in practice, most providers will put a greater or fewer number of lines in a given area depending on the severity of the features being treated.

Positioning

Patients are typically treated on a conventional examination table or chair in an examination room in the supine or partially reclining or upright position depending on provider preference. Treatment of the submental area in the upright position can be difficult with MFUS due to runoff of the fluid within the transducer when it is upside down.

Approach

DOCA is injected in the midlevel of the subcutaneous fat with a 30-gauge needle.
MFUS is delivered transcutaneously using ultrasound gel to couple the energy efficiently into the skin.

TECHNIQUES

▪ Deoxycholic Acid Injection