Yu Panxi, Zhai Haixin, Li Zhijin, Dong Ruijia, Wu Tingting, Li Yunzhu, Di Zhang, Sun Yixin, Long Xiao, Yu Nanze
The 16th Department, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Department of Plastic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
J Cosmet Dermatol. 2022 Jan;21(1):137-141. doi: 10.1111/jocd.14658. Epub 2021 Dec 12.
Botulinum neurotoxin A injection is a popular noninvasive alternative for the treatment of masseter hypertrophy. This study was conducted to identify a safe injection volume to avoid sunken lateral cheek after botulinum neurotoxin A injection in the masseter muscle.
One milliliter or 0.5 ml of indocyanine green was randomly injected into either side of the masseter muscles of 18 fresh cadaver heads. The bilateral spreads of indocyanine green within the masseter were observed by a fluorescence imager. The masseters were then dissected, and the spreading distance was measured.
Dye spreading showed an oval shape parallel to the long axis of the masseter muscle. The lower edges of the masseters were all stained with indocyanine green. The upward spreading exceeded the mouth corner-tragus line in 94.44% (17/18) of the masseters on the 1-ml side, and 11.11% (2/18) of the masseters on the 0.5-ml side. The spreading area and upward spreading distance on the 1-ml side (9.95 ± 0.48 cm , 3.18 ± 0.31 cm) were significantly larger than the 0.5-ml side (7.13 ± 0.80 cm , 2.08 ± 0.32 cm).
The spread of indocyanine green within the masseter occurs in direct proportion to its volume. A bolus of 1 ml easily exceeded the mouth corner-tragus line and cause sunken cheek.
A型肉毒杆菌神经毒素注射是治疗咬肌肥大的一种常用非侵入性方法。本研究旨在确定安全的注射剂量，以避免在咬肌注射A型肉毒杆菌神经毒素后出现脸颊外侧凹陷。
将1毫升或0.5毫升吲哚菁绿随机注射到18个新鲜尸头的咬肌两侧。通过荧光成像仪观察吲哚菁绿在咬肌内的双侧扩散情况。然后解剖咬肌，测量扩散距离。
染料扩散呈椭圆形，与咬肌长轴平行。咬肌下缘均被吲哚菁绿染色。1毫升组94.44%（17/18）的咬肌向上扩散超过口角-耳屏线，0.5毫升组为11.11%（2/18）。1毫升组的扩散面积和向上扩散距离（9.95±0.48平方厘米，3.18±0.31厘米）明显大于0.5毫升组（7.13±0.80平方厘米，2.08±0.32厘米）。
吲哚菁绿在咬肌内的扩散与其体积成正比。1毫升的推注量很容易超过口角-耳屏线并导致脸颊凹陷。
