Seong-Taek Kim

Surface anatomy of the lip elevator muscles for the treatment of gummy smile using botulinum toxin.

OBJECTIVEnTo propose a safe and reproducible injection point for botulinum toxin-A (BTX-A) as a supplementary method for the treatment of gummy smile, as determined by assessment of the morphologic characteristics of three lip elevator muscles.nnnMATERIALS AND METHODSnA total of 50 hemi-faces from 25 adult cadavers (male 13, female 12; ages, 47 to 88 years) were used in this study. Topographic relations and the directions of the lip elevator muscles (ie, levator labii superioris [LLS], levator labii superioris alaeque nasi [LLSAN], and zygomaticus minor [ZMi]), were investigated. Possible injection points were examined through the study of predetermined surface landmarks.nnnRESULTSnThe insertion of the LLS was covered partially or entirely by the LLSAN and the ZMi, and the three muscles converged on the area lateral to the ala. The mean angle between the facial midline and each muscle vector was 25.8 +/- 4.8 degrees for the LLS, 55.7 +/- 6.4 degrees for the ZMi, and -20.2 +/- 3.2 degrees for the LLSAN; no significant differences were noted between male and female subjects or between left and right sides. The three vectors passed near a triangular region formed by three surface landmarks. The center of this triangle, named the Yonsei point, was suggested as an appropriate injection point for BTX-A. The clinical effectiveness of the injection point was demonstrated in selected cases with or without orthodontic treatment.nnnCONCLUSIONSnUnder careful case selection, BTX-A may be an effective treatment alternative for patients with excessive gingival display caused by hyperactive lip elevator muscles.

Topography of the masseter muscle in relation to treatment with botulinum toxin type A.

OBJECTIVEnThe objective of this study was to provide the safest and most efficient site for injection of botulinum toxin type A into the masseter muscle.nnnSTUDY DESIGNnThis study was performed on 40 hemifaces from cadavers. The surface of the masseter was compartmentalized into areas I to VIII. Areas I, III, V, and VII were assigned to represent the upper 4 compartments from the posterior aspect of each muscle, and areas II, IV, VI, and VIII were assigned to represent the lower 4 compartments.nnnRESULTSnThe parotid gland usually covered compartments I and II, and the marginal mandibular branch of the facial nerve was located a mean of 7.4 mm above the inferior mandibular margin. The parotid duct was usually located above the reference line connecting the tragus and the cheilion.nnnCONCLUSIONnThe center of compartment VI is the safest and most efficient injection site for botulinum toxin type A into the masseter muscle.

Antinociceptive Effects of Transcytosed Botulinum Neurotoxin Type A on Trigeminal Nociception in Rats.

We examined the effects of peripherally or centrally administered botulinum neurotoxin type A (BoNT-A) on orofacial inflammatory pain to evaluate the antinociceptive effect of BoNT-A and its underlying mechanisms. The experiments were carried out on male Sprague-Dawley rats. Subcutaneous (3 U/kg) or intracisternal (0.3 or 1 U/kg) administration of BoNT-A significantly inhibited the formalin-induced nociceptive response in the second phase. Both subcutaneous (1 or 3 U/kg) and intracisternal (0.3 or 1 U/kg) injection of BoNT-A increased the latency of head withdrawal response in the complete Freunds adjuvant (CFA)-treated rats. Intracisternal administration of N-methyl-D-aspartate (NMDA) evoked nociceptive behavior via the activation of trigeminal neurons, which was attenuated by the subcutaneous or intracisternal injection of BoNT-A. Intracisternal injection of NMDA up-regulated c-Fos expression in the trigeminal neurons of the medullary dorsal horn. Subcutaneous (3 U/kg) or intracisternal (1 U/kg) administration of BoNT-A significantly reduced the number of c-Fos immunoreactive neurons in the NMDA-treated rats. These results suggest that the central antinociceptive effects the peripherally or centrally administered BoNT-A are mediated by transcytosed BoNT-A or direct inhibition of trigeminal neurons. Our data suggest that central targets of BoNT-A might provide a new therapeutic tool for the treatment of orofacial chronic pain conditions.

Topographic Relationship between the Supratrochlear Nerve and Corrugator Supercilii Muscle—Can This Anatomical Knowledge Improve the Response to Botulinum Toxin Injections in Chronic Migraine?

Chronic migraine has been related to the entrapment of the supratrochlear nerve within the corrugator supercilii muscle. Recently, research has shown that people who have undergone botulinum neurotoxin A injection in frontal regions reported disappearance or alleviation of their migraines. There have been numerous anatomical studies conducted on Caucasians revealing possible anatomical problems leading to migraine; on the other hand, relatively few anatomical studies have been conducted on Asians. Thus, the aim of the present study was to determine the topographic relationship between the supratrochlear nerve and corrugator supercilii muscle in the forehead that may be the cause of migraine. Fifty-eight hemifaces from Korean and Thai cadavers were used for this study. The supratrochlear nerve entered the corrugator supercilii muscle in every case. Type I, in which the supratrochlear nerve emerged separately from the supraorbital nerve at the medial one-third portion of the orbit, was observed in 69% (40/58) of cases. Type II, in which the supratrochlear nerve emerged from the orbit at the same location as the supraorbital nerve, was observed in 31% (18/58) of cases.

Topography of the arteries supplying the masseter muscle: Using dissection and Sihler's method.

Various surgical procedures require surgeons to have detailed knowledge of the course of blood vessels in the masseter muscle, such as masseter muscle flap formation, mandibular angle resection, parotidectomy, and mandibular ramus osteotomy. Without this knowledge serious complications can occur, endangering the lives of patients. Occasionally, during routine dissections we sometimes encounter an additional branch. The purpose of this study was to provide a comprehensive detailed anatomic description of the blood supply of the masseter muscle. This will provide critical information for various surgical procedures. Twenty‐five Korean cadavers were dissected and subjected to modified Sihlers method to reveal the branching patterns of the arteries surrounding the masseter muscle, and its intramuscular blood supply. The masseter can be supplied by seven branches from the external carotid artery. Among these, the masseteric branch from the deep temporal artery has not been described previously. This previously undescribed branch enters the medial surface of the masseter, turning medially around the anterior border of the ramus immediately after the branching point of the deep temporal artery. The branch originating from the transverse facial artery was the largest, and the branches originating from the external carotid artery and deep temporal artery were the smallest. Examination of intramuscular patterns revealed that the branches of the transverse facial artery were the most widely distributed. When considering arterial diameters and distribution areas, the branches of the transverse facial artery can be considered the main components of the seven branches supplying the masseter muscle. Clin. Anat. 25:308–313, 2012.

Antinociceptive Effects of Botulinum Toxin Type A on Trigeminal Neuropathic Pain

Previous studies have demonstrated that botulinum toxin type A (BoNT-A) attenuates orofacial nociception. However, there has been no evidence of the participation of the voltage-gated sodium channels (Navs) in the antinociceptive mechanisms of BoNT-A. This study investigated the cellular mechanisms underlying the antinociceptive effects of BoNT-A in a male Sprague-Dawley rat model of trigeminal neuropathic pain produced by malpositioned dental implants. The left mandibular second molar was extracted under anesthesia, followed by a miniature dental implant placement to induce injury to the inferior alveolar nerve. Mechanical allodynia was monitored after subcutaneous injection of BoNT-A at 3, 7, or 12 d after malpositioned dental implant surgery. Subcutaneous injections of 1 or 3 U/kg of BoNT-A on postoperative day 3 significantly attenuated mechanical allodynia, although 0.3 U/kg of BoNT-A did not affect the air-puff threshold. A single injection of 3 U/kg of BoNT-A produced prolonged antiallodynic effects over the entire experimental period. Treatment with BoNT-A on postoperative days 7 and 12, when pain had already been established, also produced prolonged antiallodynic effects. Double treatments with 1 U/kg of BoNT-A produced prolonged, more antiallodynic effects as compared with single treatments. Subcutaneous administration of 3 U/kg of BoNT-A significantly inhibited the upregulation of Nav isoform 1.7 (Nav1.7) expression in the trigeminal ganglion in the nerve-injured animals. These results suggest that antinociceptive effects of BoNT-A are mediated by an inhibition of upregulated Nav1.7 expression in the trigeminal ganglion. BoNT-A is therefore a potential new therapeutic agent for chronic pain control, including neuropathic pain.

Does Botulinum Toxin Injection into Masseter Muscles Affect Subcutaneous Thickness

BackgroundnBotulinum toxin (BoNT) is widely used to treat masseter muscle hypertrophy. Changes in the muscle thickness have been found in many studies, but there has been no report on changes in the thickness from the skin surface to the masseter muscle.nnnObjectivesnWe aimed to use ultrasonography to measure not only changes in the muscle thickness but also changes in subcutaneous thickness.nnnMethodsnThis study enrolled 20 volunteer patients: 10 were assigned to an experimental group (injected with each side 25 U of botulinum toxin into both masseter muscles) and 10 to a control group (injected with normal saline). The thicknesses were measured before the injection and at 4, 8, and 12 weeks after the injection both at rest and during maximum muscle contraction.nnnResultsnThe subcutaneous thickness did not differ significantly over time either at rest (P = 0.063) or during maximal contraction (P = 0.392), or between the experimental and control groups at rest (P = 0.392) or during maximum contraction (P = 0.259). The muscle thickness in the experimental group differed significantly over time.nnnConclusionsnBotulinum toxin injection only changes the muscle thickness and does not affect the subcutaneous thickness from the skin surface to the masseter muscle.