1989 年 82 巻 9 号 p. 1209-1219
The masseter muscle, which contributes to mastication, originates on the zygomatic arch and inserts into the lateral surface of the mandible. Although relatively rare, benign masseteric hypertrophy and intramasseteric hemangioma are two important conditions affecting this muscle. Patients with these lesions complain of the cosmetic deformity rather than the functional disorder. Unless desired for cosmetic reasons there is little justification for any operative treatment. However, as no report could be found of the esthetic problem being solved by conservative treatment, surgical correction is advised when the chief complaint is esthetic.
Surgical treatment involves resection of the hypertrophied musculature or excision of the tumor with a surrounding margin of normal muscle. We list here the important aspects of surgery of the masseter.
1) Careful preoperative planning, including CT and MRI, is indispensable.
2) An extraoral approach is preferred in most cases. The masseter muscle is exposed through a curvilinear incision around the angle of the mandible for cosmetic reasons. A postauricular incision extending to the submandibular area is used instead of a routine preauricular parotid skin incision.
3) Care should be exercised to identify and preserve the lower branches of the facial nerve. They should either be dissected free and retracted (in case of tumor) or remain on the surface of the muscle (in cases of muscle hypertrophy) to protect them from damage.
4) Ligation of the feeding vessels helps to minimize blood loss.
5) Oozing from the muscle can be controlled by an infrared contact coagulator.
6) Postoperatively continuous suction with a fenestrated polyethylene drain for 2 days and a pressure dressing for 5- to 7-days is recommended to prevent hematoma and resultant scar formation, which causes swelling or trismus.
7) Patients should begin chewing early to prevent trismus.