eMedicine Specialties > Plastic Surgery > Craniofacial
Craniofacial, Asian Malar and Mandibular Surgery: Treatment
Updated: May 1, 2009
Treatment
Medical Therapy
No medical therapy is available for zygomatic reduction. For mandibular prominence, botulinum toxin (BOTOX®) has been shown to be effective therapy in patients with a large muscle component.7 The duration of effect is currently under evaluation. Occlusal splints and other therapies have not met with consistent results.
Several publications now report on the effectiveness of botulinum in reducing the size of the masseter muscle.7,8,9,5,10 In higher doses, permanency has been obtained. The earliest studies published from abroad have used Dysport, which is not yet available in the United States. According to a 2009 Cochrane Database review, well-designed, adequately powered, randomized controlled clinical trials are needed to study the effects of BOTOX® injections as treatment for bilateral benign masseter hypertrophy.11
Optimal dosage for reducing the size of the masseter muscle is under investigation. Currently, the most common dose in the author's clinic for (BOTOX®) to the masseter muscle is 15-50 IU per side.
Surgical Therapy
Prominent zygoma
The patient is evaluated to locate the area of concern. If only the body is involved, burring the prominent portion through an intraoral incision may suffice. Wide subperiosteal dissection can lead to malar soft tissue ptosis. To prevent this, the soft tissue should be supported by suturing to the periosteum or through a drill hole along the infraorbital rim. If the arch contributes to the problem, as is usually the case, a coronal approach is frequently used. The author currently favors the coronal approach to preclude problems with malar soft tissue ptosis. The coronal approach also affords less risk to the frontal nerve as compared to a limited incision approach to the zygomatic arch.
Prominent mandibular angle
The cause of the bony prominence is determined by evaluation of the patient and radiographs. The lateral flare can be reduced using a sagittal saw or bur through an intraoral incision. The lateral flare can occur in conjunction with a prominent posterior bony angle, which is removed using a Stryker oscillating saw through an intraoral incision. Once the radiographic template of the desired resection has been marked on the bone, make the first cut at the superior (cephalic) border of the template along the posterior border of the ascending ramus. This controlled cut prevents going too high on the ascending ramus, which would risk a subcondylar fracture. After this first cut, the contouring is continued by 3-4 straight-line ostectomies, each cut moving down the mandible toward the symphysis as previously marked, followed by smoothing out of the overlapping cuts.
Preoperative Details
Prominent zygoma
Radiographs are reviewed and asymmetries noted. The relationship of the mandible is also assessed because correction of the zygoma may make the mandibular angle appear more prominent. Counsel the patient appropriately. Examination of the radiograph and the physical examination findings helps determine which components of the zygoma need to be addressed. If prominence is isolated to the body or the anterior portion of the arch, an intraoral approach suffices. If the zygomatic arch is involved, a coronal approach is necessary to adequately address the prominence.
Mandibular angle
A Panorex radiograph helps delineate the course of the inferior alveolar nerve and the amount of bone that can be safely removed. If the mandibular angle is square, a plan can be made to convert it to a more obtuse angle by using a right-angle saw to remove bone from the posterior mandibular border. If the primary problem is width from a frontal view, the lateral cortex of the mandible can be burred.
Intraoperative Details
Prominent zygoma
Full exposure of the arch and body of the zygoma is obtained through a coronal approach. Using a sagittal saw, the first osteotomy is performed at the junction of the body and arch of the zygoma. A second osteotomy is made at the arch, staying anterior to the zygomatic tubercle so that the temporomandibular joint is not violated. The osteotomized segment is repositioned cephalically, usually approximately 2 cm, and secured using wires or miniplates. The arch segments are overlapped, so that the free bone segment lies underneath the fixed segment of the arch. Bone edges at the arch and the body are burred down to prevent a step-off. A drain is placed, and the temporal fascia is sutured. An ellipse of scalp is excised prior to closure with staples, in a vector corresponding to the lateral brow–malar soft tissue junction, to help prevent cheek ptosis.
Zygomatic osteotomies are performed at the junction of the body and arch, just anterior to the zygomatic tubercle. After mobilization, the fragment is in-fractured and/or repositioned cephalically. The mandibular angle is contoured as marked.
Alternatively, a complete transection of the posterior cut followed by a greenstick infracture of the anterior cut can adequately reduce the zygoma without the need for plate or wire fixation. This technique has become the author's preferred technique. Media files 4 and 5 below show a patient before and after malar reduction through a coronal approach.
Before malar reduction through a coronal approach.
Three months after malar reduction through a coronal approach (same patient as in media file 4). The zygomatic arch has been in-fractured after osteotomies.
Mandibular contouring
An intraoral incision is made along the anterior edge of the ramus, and a subperiosteal dissection is performed. Sharp dissection using a knife or cautery is used to detach the muscle along the inferior posterior border of the mandible. To improve width, a large bur is used to reduce the protruding bone. Alternatively, a Lindemann spiral bur can be used to score or mark the desired bony excision, and then a chisel can be used to split off the offending bone fragment. A right-angle saw can be used to reduce the posterior border of the mandible to create a more obtuse angle. Of utmost importance is to protect the soft tissue at all times when using power drills or osteotomes in this highly vascular area. Bleeding from the facial artery can be difficult to control. An external incision may be necessary to control vessels that may retract under the mandible. Media files 6 and 7 show a patient before and after surgical reduction of the mandibular angle.
Reduction of mandibular angle, preoperative image. Courtesy of Robert Flowers, MD.
After surgical reduction of the mandibular angle (same patient as in media file 6). Courtesy of Robert Flowers, MD.
Postoperative Details
Zygoma reduction
Compressive dressings and drains are removed on the first postoperative day. Every other staple is removed on the third day, and the remainder of staples are removed on the seventh day. A soft diet is advanced as tolerated by the patient. Postoperative pain is mild to moderate. Swelling resolves enough for the patient to return to work approximately 10 days after the procedure.
Mandibular contouring
Postoperative trismus is to be expected, and exercises to stretch the masseter muscle should begin after 1 week. Compressive dressings are worn for 1 week. The diet is advanced from a clear diet the first day, to a liquid diet for the first week, and then to a soft diet for another week.
Trismus can be significant if the masseter muscle was partially removed as part of therapy. The patient is instructed in mouth opening exercises for the first 2-3 weeks.
Complications
Malar surgery
The frontal nerve can occasionally be injured during the coronal approach. Traction injuries resolve within 6-12 months. Transection of the nerve requires treatment by denervating the opposite frontal nerve (surgically or with botulinum toxin injection) and/or a hemicoronal lift.
Asymmetry
Preoperative asymmetry should be pointed out to the patient. The advantage of a coronal approach to malar reduction is the maximum control over the bone segment and the opportunity to compare both sides simultaneously. Persistent postoperative asymmetry may necessitate reoperation.
Step-off
A mild degree of step-off can occur. This can be minimized by burring down the contact surfaces of bone.
Mandible
The marginal nerve lies in a plane superficial to the masseter muscle. The nerve is potentially at risk during resection of the masseter muscle or during the use of power instruments without adequate protection.
The facial artery lies at the anterior border of the masseter muscle. The subperiosteal dissection must remain in the proper plane. In addition, when using a power instrument, protection of the soft tissue is critical to the safe execution of the operation.
Subcondylar fracture can result from an unfavorable fracture line extending from the angle of the mandible. A horizontal back-cut along the posterior border at the superior limit can reduce this risk.
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References
Onizuka T, Watanabe K, Takasu K, Keyama A. Reduction malar plasty. Aesthetic Plast Surg. 1983;7(2):121-5. [Medline].
Watanabe K. Cosmetic contouring of the midface. In: Song IC, ed. Facial Cosmetic Surgery in Orientals. Problems in Plastic and Reconstructive Surgery. Vol 1. 1991:643-53.
Baek SM, Chung YD, Kim SS. Reduction malarplasty. Plast Reconstr Surg. Jul 1991;88(1):53-61. [Medline].
Morris DE, Moaveni Z, Lo LJ. Aesthetic facial skeletal contouring in the Asian patient. Clin Plast Surg. Jul 2007;34(3):547-56. [Medline].
Ahn J, Horn C, Blitzer A. Botulinum toxin for masseter reduction in Asian patients. Arch Facial Plast Surg. May-Jun 2004;6(3):188-91. [Medline].
Baek SM, Kim SS, Bindiger A. The prominent mandibular angle: preoperative management, operative technique, and results in 42 patients. Plast Reconstr Surg. Feb 1989;83(2):272-80. [Medline].
Kim JH, Shin JH, Kim ST, Kim CY. Effects of two different units of botulinum toxin type a evaluated by computed tomography and electromyographic measurements of human masseter muscle. Plast Reconstr Surg. Feb 2007;119(2):711-7. [Medline].
Al-Ahmad HT, Al-Qudah MA. The treatment of masseter hypertrophy with botulinum toxin type A. Saudi Med J. Mar 2006;27(3):397-400. [Medline].
Castro WH, Gomez RS, Da Silva Oliveira J, Moura MD, Gomez RS. Botulinum toxin type A in the management of masseter muscle hypertrophy. J Oral Maxillofac Surg. Jan 2005;63(1):20-4. [Medline].
von Lindern JJ, Niederhagen B, Appel T, Berge S, Reich RH. Type A botulinum toxin for the treatment of hypertrophy of the masseter and temporal muscles: an alternative treatment. Plast Reconstr Surg. Feb 2001;107(2):327-32. [Medline].
Al-Muharraqi MA, Fedorowicz Z, Al Bareeq J, Al Bareeq R, Nasser M. Botulinum toxin for masseter hypertrophy. Cochrane Database Syst Rev. Jan 21 2009;CD007510. [Medline].
Kang J, Han K. Cosmetic contouring of the lowerface. In: Song IC, ed. Facial Cosmetic Surgery in Orientals. Problems in Plastic and Reconstructive Surgery. Vol 1. 1991:654-66.
Ousterhout D. Mandibular width reduction including surgical treatment of benign masseteric hypertrophy. In: Aesthetic Contouring of the Craniofacial Skeleton. Boston, Mass: Little Brown; 1991:451-69.
Further Reading
Keywords
malar surgery, mandibular surgery, Asian malar surgery, Asian mandibular surgery, cheek bone reduction, malar reduction, reduction malarplasty, zygoma reduction, zygomatic reduction, reduction zygomaplasty, Asian malarplasty, benign masseteric hypertrophy, jawline contouring, jawline reduction, mandible reduction, jawline shaving, bone contouring, facial bone surgery, BOTOX® jawline, BOTOX® jaw muscle, BOTOX® masseter muscle, botulinum toxin therapy, botulinum toxin, BOTOX®, masseteric hypertrophy, work hypertrophy, habitual jaw clenching, habitual teeth grinding, teeth grinding, jaw clenching, prominent malar bones, malar prominence, zygomatic prominence, Asian plastic surgery, oriental plastic surgery
