Ultrasound-Guided Botulinum Neurotoxin Type A Injection for Correcting Asymmetrical Smiles

Ultrasound-Guided Botulinum Neurotoxin Type A Injection for Correcting Asymmetrical Smiles Abstract While ultrasound-guided injections are safer and more effective than the typical (blind) injection methods, there has been no report of ultrasound-guided injection techniques being applied to patients for aesthetic treatment or to patients with an asymmetrical smile. The purpose of this study was to determine the locations of facial expression muscles using ultrasound and to use this information to guide BoNT-A injections into a patient with an asymmetrical smile. The safety and effectiveness of this technique were also evaluated. A real-time two-dimensional B-mode ultrasound system (E-CUBE 15 EX, ALPINION, Seoul, Korea) with a 30-mm-wide linear array transducer (8.0-17.0 MHz; IO8-17 high frequency hockey stick, Seoul, Korea) was used to obtain images of the depressor labii inferioris (DLI), risorius, depressor anguli oris (DAO), and zygomaticus major (ZMj). The patient received an ultrasound-guided BoNT-A injection (Meditoxin®, Medytox, Seoul, Korea) in each target muscle using a 1-mL syringe with a 30-gauge 1-inch-long needle. The patient’s smile was symmetrical 1 month after the US-guided BoNT-A into the DLI, risorius, and ZMj. The symmetry was achieved by decreasing the exposure of the lower teeth and by elevating both mouth corners. The ultrasound-guided injection technique may contribute to the determination of the optimal injection method and dosage based on a precise knowledge of morphology, location, layer of target muscles, and thickness of subcutaneous fat tissues. Level of Evidence: 5 While ultrasound-guided injections are safer and more effective than the typical (blind) injection methods, clinicians today rarely utilize ultrasound guidance for injections into the face.1–3 It is more difficult to utilize ultrasounds to identify facial expression muscles than to identify trunk muscles or muscles in the upper or lower extremities, as facial expression muscles are interwoven with their surrounding muscles or connective tissues at the insertion site.4,5 This difficulty has meant, to the best of our knowledge, that there has been no report of ultrasound-guided injection techniques being applied to patients for aesthetic treatment or to patients with an asymmetrical smile. The purpose of this study was to determine the locations of facial expression muscles using ultrasound and to use this information to guide BoNT-A injections into a patient with an asymmetrical smile. The safety and effectiveness of this technique were also evaluated. CASE REPORT A 30-year-old woman was referred to a clinic due to her asymmetrical smile. When we saw this patient, her left lower teeth were exposed while her right lower teeth remained hidden, and the left corner of her mouth was more elevated than the right corner when she smiled. Her history was as follows: 2 months following her birth, the patient’s left lower teeth became exposed when crying. She visited a hospital, and her parents were told by a doctor that it was not a major problem and that it would improve with age. However, by age 4, she showed no signs of improvement, so she visited another pediatrician who gave her the same diagnosis as the first. The patient suffered from stress because of her asymmetrical smile—when she smiled, she always placed a hand over her mouth. Her medical history showed that she had received an autogenous fat graft and orthognathic surgery in both jaws 5 years past. The exposure of her left lower teeth slightly improved after surgery, but it relapsed 2 months thereafter. A signed and written informed consent was obtained from the patient. The research was approved by the institutional review board of Yonsei University College of Dentistry (2016.09.29; Approved No. 2-2016-0024). A real-time two-dimensional B-mode ultrasound system (E-CUBE 15 EX, ALPINION, Seoul, Korea) with a 30-mm-wide linear array transducer (8.0-17.0 MHz; IO8-17 high frequency hockey stick, Seoul, Korea) was used to obtain images of the depressor labii inferioris (DLI), risorius, depressor anguli oris (DAO), and zygomaticus major (ZMj) (Figure 1). Figure 1. View largeDownload slide Ultrasound images of the patient’s left lower face and their corresponding illustrations. (A) An ultrasound image of the DLI and depressor anguli oris DAO and (B) its corresponding illustration in the resting condition. (C) An ultrasound image of the DAO and the risorius superficial to the buccinator (Buc) and (D) its corresponding illustration in resting condition. (E) An ultrasound image of the zygomaticus minor (Zmi) was identified below the zygomaticus major (ZMj) and (F) its corresponding illustration. The levator anguli oris (LAO) was observed at the deeper-most part of the midface near the nose alar. The transducer was always placed perpendicular to the lower face skin or mandible, and images were taken in the transverse plane (A, anterior; L, lateral aspect). Figure 1. View largeDownload slide Ultrasound images of the patient’s left lower face and their corresponding illustrations. (A) An ultrasound image of the DLI and depressor anguli oris DAO and (B) its corresponding illustration in the resting condition. (C) An ultrasound image of the DAO and the risorius superficial to the buccinator (Buc) and (D) its corresponding illustration in resting condition. (E) An ultrasound image of the zygomaticus minor (Zmi) was identified below the zygomaticus major (ZMj) and (F) its corresponding illustration. The levator anguli oris (LAO) was observed at the deeper-most part of the midface near the nose alar. The transducer was always placed perpendicular to the lower face skin or mandible, and images were taken in the transverse plane (A, anterior; L, lateral aspect). The first treatment was conducted in January 2017. The patient was positioned supinely on an examination bench that was angled at 45 degrees. After identifying the patient’s modiolus, the location of the DAO was confirmed on the sagittal reference line that passes the modiolus.6,7 When the transducer was placed longitudinally from the modiolus, the DAO was identified, and the transducer was moved medially to verify the position of the DLI, which is located deeper than the DAO. In the same way, the transducer was moved laterally from the modiolus to confirm the position of the risorius.8,9 After confirming the positions of these 3 perioral muscles with the transducer at a vertical orientation, the transducer was placed transversely and moved medially to verify the DAO and the DLI. When the 3 muscles had been identified, the patient was asked to contract and relax each muscle in turn. This process was repeated until the exact location of each muscle was confirmed. The right hand was used to obtain an ultrasound image, while the left arm supported the right arm so as to hold it steady. Water-soluble transmission gel was applied to reduce the external pressure required on the dermal surface to obtain clear images. The transducer was always placed perpendicular to the lower face skin or mandible, and images were taken in the transverse plane. In every ultrasonographical image of the patient’s face, the DAO, shown as a thicker muscle bundle, was located more superficially than the DLI (Figure 1A). A thin risorius was interlaced with the lateral aspect of the DAO, and the buccinator was observed deep to the risorius (Figure 1B). At the meeting point between the horizontal line passing the nose ala and the perpendicular line passing the lateral canthus, the ZMj was identified and observed as a thick muscle bundle. At this point, the zygomaticus minor was located medial to the ZMj while the levator anguli oris was deep to the ZMj and minor (Figure 1C). The patient received an ultrasound-guided BoNT-A injection (Meditoxin®, Medytox, Seoul, Korea) in each target muscle using a 1-mL syringe with a 30-gauge 1-inch-long needle (Figure 2). After using ultrasound to confirm the location of the tip of the needle within the target muscles (the left DLI and risorius), an ultrasound-guided BoNT-A injection was performed. The position of the needle tip was monitored on the ultrasound screen throughout the procedure. The doses of BoNT-A applied to the DLI and the risorius were 5 U and 2 U, respectively. Figure 2. View largeDownload slide Ultrasound-guided injections of BoNT-A into the patient’s face. BoNT-A was injected into the depressor labii inferioris (DLI) and risorius at 5 U and 2 U, respectively (blue arrows). One month later, an additional 3 U and 4 U of BoNT-A were injected into the DLI and zygomaticus major (ZMj), respectively (red arrows). (A) Ultrasound and ultrasound-guided injection images of the patient’s left lower face, (B) positioning the needle into the DLI, (C) into the risoius, and (D) into the ZMj. Arrowheads indicate the needle (DLI, depressor labii inferioris; R, risorius; ZMj; zygomaticus manjor; A, anterior; L, lateral aspect). Figure 2. View largeDownload slide Ultrasound-guided injections of BoNT-A into the patient’s face. BoNT-A was injected into the depressor labii inferioris (DLI) and risorius at 5 U and 2 U, respectively (blue arrows). One month later, an additional 3 U and 4 U of BoNT-A were injected into the DLI and zygomaticus major (ZMj), respectively (red arrows). (A) Ultrasound and ultrasound-guided injection images of the patient’s left lower face, (B) positioning the needle into the DLI, (C) into the risoius, and (D) into the ZMj. Arrowheads indicate the needle (DLI, depressor labii inferioris; R, risorius; ZMj; zygomaticus manjor; A, anterior; L, lateral aspect). Post-injection photographs were taken a month following the procedure in February 2017. After her first treatment, the patient’s left lower teeth remained exposed, and her left mouth corner elevation was not sufficiently enhanced. Therefore, an additional 3 U and 4 U of BoNT-A injections were injected into the DLI and the left ZMj, respectively, under ultrasound guidance in the same way as in the previous intervention (Figure 2). The touch-up injection was performed because the patient wanted the asymmetry to be corrected even more when she visited the month following her first treatment. Her asymmetrical smile, caused by the DLI and the risorius, was improved. But a follow-up evaluation revealed that the ZMj had not been completely paralyzed, while the DLI appeared to have been more corrected. That is why we performed an additional injection into the ZMj and a lightly dosed injection into the DLI. From the US images, significant differences, such as muscle mass reduction or less mobility of the muscle, were not observed, as most facial muscles such as the DAO and the DLI are very thin and tiny compared to other skeletal muscles. The patient’s smile was symmetrical 3 months after the ultrasound-guided BoNT-A into the DLI, risorius, and ZMj. The symmetry was achieved by decreasing the exposure of the lower teeth and by elevating both mouth corners (Figure 3). Patient satisfaction was assessed through an interview, and she reported being happy and satisfied with the outcome. Four months after the follow-up treatment, she visited our clinic again, and regular check-ups have been scheduled for every 4 months. Figure 3. View largeDownload slide Photographs of the 30-year-old female patient’s lower face (A) before and (B) 1 month after the ultrasound-guided injections. When the patient smiled, her left lower teeth were exposed, while the corner of her left mouth seemed relatively elevated by the zygomaticus major and the risorius in contrast to the right corner of her mouth. The patient’s smile was symmetrical 4 weeks after injecting the BoNT-A into the depressor labii inferioris, ZMj, and risorius. This symmetry was achieved by decreasing the exposure of the lower teeth and elevating both mouth corners. Figure 3. View largeDownload slide Photographs of the 30-year-old female patient’s lower face (A) before and (B) 1 month after the ultrasound-guided injections. When the patient smiled, her left lower teeth were exposed, while the corner of her left mouth seemed relatively elevated by the zygomaticus major and the risorius in contrast to the right corner of her mouth. The patient’s smile was symmetrical 4 weeks after injecting the BoNT-A into the depressor labii inferioris, ZMj, and risorius. This symmetry was achieved by decreasing the exposure of the lower teeth and elevating both mouth corners. DISCUSSION To our knowledge, this is the first report of performing an ultrasound-guided BoNT-A injection into facial expression muscles to correct an asymmetrical smile. The patient in this study had a medical history of an autogenous fat graft, and thus the subcutaneous fat in her midface was thicker than normal. In this particular case, the muscle could have been deeper than in a normal face. If these characteristics had not been considered, the BoNT-A could have been injected into the subcutaneous fat layer, leading not only to a less-effective treatment but also to a greater diffusion into surrounding muscles. Therefore, the thickness of the subcutaneous fat layer should be considered before performing BoNT-A injections in order to ensure a good outcome with fewer side effects. CONCLUSIONS The ultrasound-guided injection technique presented in this article may contribute to the determination of the optimal injection method and dosage based on a precise knowledge of morphology, location, layer of target muscles, and thickness of subcutaneous fat tissues. This technique could also be beneficial to other aesthetic treatments by reducing various serious side effects. Disclosures The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article. Funding This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (NRF-2017R1A2B4003781). Acknowledgments The authors thank Hwi Eun Hur from Davidson College for her assistance in revising this manuscript. REFERENCES 1. Quezada-Gaon N , Wortsman X , Peñaloza O , Carrasco JE . Comparison of clinical marking and ultrasound-guided injection of Botulinum type A toxin into the masseter muscles for treating bruxism and its cosmetic effects . J Cosmet Dermatol . 2016 ; 15 ( 3 ): 238 - 244 . Google Scholar CrossRef Search ADS PubMed 2. Quezada-Gaón N , Wortsman X . Ultrasound-guided hyaluronidase injection in cosmetic complications . J Eur Acad Dermatol Venereol . 2016 ; 30 ( 10 ): e39 - e40 . Google Scholar CrossRef Search ADS PubMed 3. Wortsman X , Wortsman J , Orlandi C , Cardenas G , Sazunic I , Jemec GB . Ultrasound detection and identification of cosmetic fillers in the skin . J Eur Acad Dermatol Venereol . 2012 ; 26 ( 3 ): 292 - 301 . Google Scholar CrossRef Search ADS PubMed 4. Alfen NV , Gilhuis HJ , Keijzers JP , Pillen S , Van Dijk JP . Quantitative facial muscle ultrasound: feasibility and reproducibility . Muscle Nerve . 2013 ; 48 ( 3 ): 375 - 380 . Google Scholar CrossRef Search ADS PubMed 5. Kim HJ , Seo KK , Lee HK , Kim J. Clinical Anatomy of the Face for Filler and Botulinum Toxin Injection . Singapore : Springer ; 2016 . 6. Choi YJ , Kim JS , Gil YC , et al. Anatomical considerations regarding the location and boundary of the depressor anguli oris muscle with reference to botulinum toxin injection . Plast Reconstr Surg . 2014 ; 134 ( 5 ): 917 - 921 . Google Scholar CrossRef Search ADS PubMed 7. Hur MS , Hu KS , Cho JY , et al. Topography and location of the depressor anguli oris muscle with a reference to the mental foramen . Surg Radiol Anat . 2008 ; 30 ( 5 ): 403 - 407 . Google Scholar CrossRef Search ADS PubMed 8. Bae JH , Choi DY , Lee JG , Seo KK , Tansatit T , Kim HJ . The risorius muscle: anatomic considerations with reference to botulinum neurotoxin injection for masseteric hypertrophy . Dermatol Surg . 2014 ; 40 ( 12 ): 1334 - 1339 . Google Scholar CrossRef Search ADS PubMed 9. Kim HS , Pae C , Bae JH , et al. An anatomical study of the risorius in Asians and its insertion at the modiolus . Surg Radiol Anat . 2015 ; 37 ( 2 ): 147 - 151 . Google Scholar CrossRef Search ADS PubMed © 2018 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aesthetic Surgery Journal Oxford University Press

Ultrasound-Guided Botulinum Neurotoxin Type A Injection for Correcting Asymmetrical Smiles

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© 2018 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com
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Abstract

Abstract While ultrasound-guided injections are safer and more effective than the typical (blind) injection methods, there has been no report of ultrasound-guided injection techniques being applied to patients for aesthetic treatment or to patients with an asymmetrical smile. The purpose of this study was to determine the locations of facial expression muscles using ultrasound and to use this information to guide BoNT-A injections into a patient with an asymmetrical smile. The safety and effectiveness of this technique were also evaluated. A real-time two-dimensional B-mode ultrasound system (E-CUBE 15 EX, ALPINION, Seoul, Korea) with a 30-mm-wide linear array transducer (8.0-17.0 MHz; IO8-17 high frequency hockey stick, Seoul, Korea) was used to obtain images of the depressor labii inferioris (DLI), risorius, depressor anguli oris (DAO), and zygomaticus major (ZMj). The patient received an ultrasound-guided BoNT-A injection (Meditoxin®, Medytox, Seoul, Korea) in each target muscle using a 1-mL syringe with a 30-gauge 1-inch-long needle. The patient’s smile was symmetrical 1 month after the US-guided BoNT-A into the DLI, risorius, and ZMj. The symmetry was achieved by decreasing the exposure of the lower teeth and by elevating both mouth corners. The ultrasound-guided injection technique may contribute to the determination of the optimal injection method and dosage based on a precise knowledge of morphology, location, layer of target muscles, and thickness of subcutaneous fat tissues. Level of Evidence: 5 While ultrasound-guided injections are safer and more effective than the typical (blind) injection methods, clinicians today rarely utilize ultrasound guidance for injections into the face.1–3 It is more difficult to utilize ultrasounds to identify facial expression muscles than to identify trunk muscles or muscles in the upper or lower extremities, as facial expression muscles are interwoven with their surrounding muscles or connective tissues at the insertion site.4,5 This difficulty has meant, to the best of our knowledge, that there has been no report of ultrasound-guided injection techniques being applied to patients for aesthetic treatment or to patients with an asymmetrical smile. The purpose of this study was to determine the locations of facial expression muscles using ultrasound and to use this information to guide BoNT-A injections into a patient with an asymmetrical smile. The safety and effectiveness of this technique were also evaluated. CASE REPORT A 30-year-old woman was referred to a clinic due to her asymmetrical smile. When we saw this patient, her left lower teeth were exposed while her right lower teeth remained hidden, and the left corner of her mouth was more elevated than the right corner when she smiled. Her history was as follows: 2 months following her birth, the patient’s left lower teeth became exposed when crying. She visited a hospital, and her parents were told by a doctor that it was not a major problem and that it would improve with age. However, by age 4, she showed no signs of improvement, so she visited another pediatrician who gave her the same diagnosis as the first. The patient suffered from stress because of her asymmetrical smile—when she smiled, she always placed a hand over her mouth. Her medical history showed that she had received an autogenous fat graft and orthognathic surgery in both jaws 5 years past. The exposure of her left lower teeth slightly improved after surgery, but it relapsed 2 months thereafter. A signed and written informed consent was obtained from the patient. The research was approved by the institutional review board of Yonsei University College of Dentistry (2016.09.29; Approved No. 2-2016-0024). A real-time two-dimensional B-mode ultrasound system (E-CUBE 15 EX, ALPINION, Seoul, Korea) with a 30-mm-wide linear array transducer (8.0-17.0 MHz; IO8-17 high frequency hockey stick, Seoul, Korea) was used to obtain images of the depressor labii inferioris (DLI), risorius, depressor anguli oris (DAO), and zygomaticus major (ZMj) (Figure 1). Figure 1. View largeDownload slide Ultrasound images of the patient’s left lower face and their corresponding illustrations. (A) An ultrasound image of the DLI and depressor anguli oris DAO and (B) its corresponding illustration in the resting condition. (C) An ultrasound image of the DAO and the risorius superficial to the buccinator (Buc) and (D) its corresponding illustration in resting condition. (E) An ultrasound image of the zygomaticus minor (Zmi) was identified below the zygomaticus major (ZMj) and (F) its corresponding illustration. The levator anguli oris (LAO) was observed at the deeper-most part of the midface near the nose alar. The transducer was always placed perpendicular to the lower face skin or mandible, and images were taken in the transverse plane (A, anterior; L, lateral aspect). Figure 1. View largeDownload slide Ultrasound images of the patient’s left lower face and their corresponding illustrations. (A) An ultrasound image of the DLI and depressor anguli oris DAO and (B) its corresponding illustration in the resting condition. (C) An ultrasound image of the DAO and the risorius superficial to the buccinator (Buc) and (D) its corresponding illustration in resting condition. (E) An ultrasound image of the zygomaticus minor (Zmi) was identified below the zygomaticus major (ZMj) and (F) its corresponding illustration. The levator anguli oris (LAO) was observed at the deeper-most part of the midface near the nose alar. The transducer was always placed perpendicular to the lower face skin or mandible, and images were taken in the transverse plane (A, anterior; L, lateral aspect). The first treatment was conducted in January 2017. The patient was positioned supinely on an examination bench that was angled at 45 degrees. After identifying the patient’s modiolus, the location of the DAO was confirmed on the sagittal reference line that passes the modiolus.6,7 When the transducer was placed longitudinally from the modiolus, the DAO was identified, and the transducer was moved medially to verify the position of the DLI, which is located deeper than the DAO. In the same way, the transducer was moved laterally from the modiolus to confirm the position of the risorius.8,9 After confirming the positions of these 3 perioral muscles with the transducer at a vertical orientation, the transducer was placed transversely and moved medially to verify the DAO and the DLI. When the 3 muscles had been identified, the patient was asked to contract and relax each muscle in turn. This process was repeated until the exact location of each muscle was confirmed. The right hand was used to obtain an ultrasound image, while the left arm supported the right arm so as to hold it steady. Water-soluble transmission gel was applied to reduce the external pressure required on the dermal surface to obtain clear images. The transducer was always placed perpendicular to the lower face skin or mandible, and images were taken in the transverse plane. In every ultrasonographical image of the patient’s face, the DAO, shown as a thicker muscle bundle, was located more superficially than the DLI (Figure 1A). A thin risorius was interlaced with the lateral aspect of the DAO, and the buccinator was observed deep to the risorius (Figure 1B). At the meeting point between the horizontal line passing the nose ala and the perpendicular line passing the lateral canthus, the ZMj was identified and observed as a thick muscle bundle. At this point, the zygomaticus minor was located medial to the ZMj while the levator anguli oris was deep to the ZMj and minor (Figure 1C). The patient received an ultrasound-guided BoNT-A injection (Meditoxin®, Medytox, Seoul, Korea) in each target muscle using a 1-mL syringe with a 30-gauge 1-inch-long needle (Figure 2). After using ultrasound to confirm the location of the tip of the needle within the target muscles (the left DLI and risorius), an ultrasound-guided BoNT-A injection was performed. The position of the needle tip was monitored on the ultrasound screen throughout the procedure. The doses of BoNT-A applied to the DLI and the risorius were 5 U and 2 U, respectively. Figure 2. View largeDownload slide Ultrasound-guided injections of BoNT-A into the patient’s face. BoNT-A was injected into the depressor labii inferioris (DLI) and risorius at 5 U and 2 U, respectively (blue arrows). One month later, an additional 3 U and 4 U of BoNT-A were injected into the DLI and zygomaticus major (ZMj), respectively (red arrows). (A) Ultrasound and ultrasound-guided injection images of the patient’s left lower face, (B) positioning the needle into the DLI, (C) into the risoius, and (D) into the ZMj. Arrowheads indicate the needle (DLI, depressor labii inferioris; R, risorius; ZMj; zygomaticus manjor; A, anterior; L, lateral aspect). Figure 2. View largeDownload slide Ultrasound-guided injections of BoNT-A into the patient’s face. BoNT-A was injected into the depressor labii inferioris (DLI) and risorius at 5 U and 2 U, respectively (blue arrows). One month later, an additional 3 U and 4 U of BoNT-A were injected into the DLI and zygomaticus major (ZMj), respectively (red arrows). (A) Ultrasound and ultrasound-guided injection images of the patient’s left lower face, (B) positioning the needle into the DLI, (C) into the risoius, and (D) into the ZMj. Arrowheads indicate the needle (DLI, depressor labii inferioris; R, risorius; ZMj; zygomaticus manjor; A, anterior; L, lateral aspect). Post-injection photographs were taken a month following the procedure in February 2017. After her first treatment, the patient’s left lower teeth remained exposed, and her left mouth corner elevation was not sufficiently enhanced. Therefore, an additional 3 U and 4 U of BoNT-A injections were injected into the DLI and the left ZMj, respectively, under ultrasound guidance in the same way as in the previous intervention (Figure 2). The touch-up injection was performed because the patient wanted the asymmetry to be corrected even more when she visited the month following her first treatment. Her asymmetrical smile, caused by the DLI and the risorius, was improved. But a follow-up evaluation revealed that the ZMj had not been completely paralyzed, while the DLI appeared to have been more corrected. That is why we performed an additional injection into the ZMj and a lightly dosed injection into the DLI. From the US images, significant differences, such as muscle mass reduction or less mobility of the muscle, were not observed, as most facial muscles such as the DAO and the DLI are very thin and tiny compared to other skeletal muscles. The patient’s smile was symmetrical 3 months after the ultrasound-guided BoNT-A into the DLI, risorius, and ZMj. The symmetry was achieved by decreasing the exposure of the lower teeth and by elevating both mouth corners (Figure 3). Patient satisfaction was assessed through an interview, and she reported being happy and satisfied with the outcome. Four months after the follow-up treatment, she visited our clinic again, and regular check-ups have been scheduled for every 4 months. Figure 3. View largeDownload slide Photographs of the 30-year-old female patient’s lower face (A) before and (B) 1 month after the ultrasound-guided injections. When the patient smiled, her left lower teeth were exposed, while the corner of her left mouth seemed relatively elevated by the zygomaticus major and the risorius in contrast to the right corner of her mouth. The patient’s smile was symmetrical 4 weeks after injecting the BoNT-A into the depressor labii inferioris, ZMj, and risorius. This symmetry was achieved by decreasing the exposure of the lower teeth and elevating both mouth corners. Figure 3. View largeDownload slide Photographs of the 30-year-old female patient’s lower face (A) before and (B) 1 month after the ultrasound-guided injections. When the patient smiled, her left lower teeth were exposed, while the corner of her left mouth seemed relatively elevated by the zygomaticus major and the risorius in contrast to the right corner of her mouth. The patient’s smile was symmetrical 4 weeks after injecting the BoNT-A into the depressor labii inferioris, ZMj, and risorius. This symmetry was achieved by decreasing the exposure of the lower teeth and elevating both mouth corners. DISCUSSION To our knowledge, this is the first report of performing an ultrasound-guided BoNT-A injection into facial expression muscles to correct an asymmetrical smile. The patient in this study had a medical history of an autogenous fat graft, and thus the subcutaneous fat in her midface was thicker than normal. In this particular case, the muscle could have been deeper than in a normal face. If these characteristics had not been considered, the BoNT-A could have been injected into the subcutaneous fat layer, leading not only to a less-effective treatment but also to a greater diffusion into surrounding muscles. Therefore, the thickness of the subcutaneous fat layer should be considered before performing BoNT-A injections in order to ensure a good outcome with fewer side effects. CONCLUSIONS The ultrasound-guided injection technique presented in this article may contribute to the determination of the optimal injection method and dosage based on a precise knowledge of morphology, location, layer of target muscles, and thickness of subcutaneous fat tissues. This technique could also be beneficial to other aesthetic treatments by reducing various serious side effects. Disclosures The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article. Funding This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (NRF-2017R1A2B4003781). Acknowledgments The authors thank Hwi Eun Hur from Davidson College for her assistance in revising this manuscript. REFERENCES 1. Quezada-Gaon N , Wortsman X , Peñaloza O , Carrasco JE . Comparison of clinical marking and ultrasound-guided injection of Botulinum type A toxin into the masseter muscles for treating bruxism and its cosmetic effects . J Cosmet Dermatol . 2016 ; 15 ( 3 ): 238 - 244 . Google Scholar CrossRef Search ADS PubMed 2. Quezada-Gaón N , Wortsman X . Ultrasound-guided hyaluronidase injection in cosmetic complications . J Eur Acad Dermatol Venereol . 2016 ; 30 ( 10 ): e39 - e40 . Google Scholar CrossRef Search ADS PubMed 3. Wortsman X , Wortsman J , Orlandi C , Cardenas G , Sazunic I , Jemec GB . Ultrasound detection and identification of cosmetic fillers in the skin . J Eur Acad Dermatol Venereol . 2012 ; 26 ( 3 ): 292 - 301 . Google Scholar CrossRef Search ADS PubMed 4. Alfen NV , Gilhuis HJ , Keijzers JP , Pillen S , Van Dijk JP . Quantitative facial muscle ultrasound: feasibility and reproducibility . Muscle Nerve . 2013 ; 48 ( 3 ): 375 - 380 . Google Scholar CrossRef Search ADS PubMed 5. Kim HJ , Seo KK , Lee HK , Kim J. Clinical Anatomy of the Face for Filler and Botulinum Toxin Injection . Singapore : Springer ; 2016 . 6. Choi YJ , Kim JS , Gil YC , et al. Anatomical considerations regarding the location and boundary of the depressor anguli oris muscle with reference to botulinum toxin injection . Plast Reconstr Surg . 2014 ; 134 ( 5 ): 917 - 921 . Google Scholar CrossRef Search ADS PubMed 7. Hur MS , Hu KS , Cho JY , et al. Topography and location of the depressor anguli oris muscle with a reference to the mental foramen . Surg Radiol Anat . 2008 ; 30 ( 5 ): 403 - 407 . Google Scholar CrossRef Search ADS PubMed 8. Bae JH , Choi DY , Lee JG , Seo KK , Tansatit T , Kim HJ . The risorius muscle: anatomic considerations with reference to botulinum neurotoxin injection for masseteric hypertrophy . Dermatol Surg . 2014 ; 40 ( 12 ): 1334 - 1339 . Google Scholar CrossRef Search ADS PubMed 9. Kim HS , Pae C , Bae JH , et al. An anatomical study of the risorius in Asians and its insertion at the modiolus . Surg Radiol Anat . 2015 ; 37 ( 2 ): 147 - 151 . Google Scholar CrossRef Search ADS PubMed © 2018 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

Aesthetic Surgery JournalOxford University Press

Published: Sep 1, 2018

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