ARticle | boTulInuM ToxIn A |
Treatment implications when injecting the mentalis
1 Inject botulinum toxin
transverse mental crease and at the apex of the mental protuberance.
placed deeply, and in one site centrally or in two sites separately on either side of the midline depending on the width of the chin.
2Injections can be 3High-volume injections
or a heavy-handed technique can cause diffusion of the toxin into the orbicularis oris or depressor labii inferioris, or both, and produce motor dysfunction of the lower lip and sphincter incompetence of the buccal aperture.
botulinum toxin can correct postoperative chin puckering and distortions resulting from mentoplasty.
4Injections of 5Botulinum toxin A can
enhancement produced by soft tissue filler injections of the perimental and peribuccal areas.
prolong the A far below the occur when vigorous massage is performed after
injection. If the orbicularis oris or depressor labii inferioris is inadvertently affected, a relaxation of a tight oral sphincter, a reduction in lip competence, and a diminution in buccal motor movements will occur. This can cause the patient to articulate certain sounds with difficulty. overzealous treatment will cause an inability to approximate the lower lip tightly against the teeth, producing involuntary dribbling from the lower lip when drinking, or drooling from the corners of the mouth when at rest.
Jawline blunting and wrinkling of the upper platysma With age, there is a descent of soft tissue from the mid face to the mandibular border20
and up the lateral neck. Its anterior fibres from both sheets of muscle on either side of the neck interdigitate in different patterns at or near the symphysis menti of the mandible. The posterior fibres pass over the lower border of the body of the mandible superficial to the marginal mandibular branch of the facial nerve, artery, and vein. This upper part of the platysma is divided into three portions and is a contributor to the orbicularis oris complex2
. The upper fibres of the platysma called pars mandibularis . The platysma can become
hyperkinetic and the skin of the face and neck becomes lax and drapes randomly over the mandibular border, overhanging and blunting the cervicofacial angle. Patients who can displace and elevate their platysma and make their mandibular border disappear by pulling down hard on their platysma, are ideal candidates for treatment. In addition, there is a small subset of patients whose upper platysma is very active and hyperkinetic, creating a variety of perioral lines with the slightest bit of buccal movement. lower facial platysmal lines become more obtrusive when the bearer loses weight, and the skin becomes lax and inelastic with time (Figure 6).
Functional anatomy The platysma comprises two separate broad, thin sheets of muscle running up the front and lateral aspects of the neck from the upper chest to the mandible, fusing and blending its muscle fibres with the superficial muscular aponeurotic system (SMAS)21
. The platysma originates from the
superficial fascia of the upper part of the thorax over the pectoralis major and deltoid. It ascends in a superomedial direction across the clavicle and acromion of the scapula
insert into the lower border of the body of the mandible below the oblique line and into the skin and subcutaneous tissue of the lower part of the face. Posterior to the attachment, separate muscle fibres pass superomedially to interdigitate with the lateral fibres of the depressor anguli oris. other fibres of the platysma travel deep to the depressor anguli oris and re‑emerge medial to it. fibres of the platysma may be present as high as the ear
or zygoma, participating in the formation of the SMAS in the lower and lateral aspects of the face. The platysma pars modiolaris comprises the remaining fibres of the upper platysma posterior to the platysma pars labialis and is posterolateral to the fibres of the depressor anguli oris. They pass superomedially deep to the risorius and into the apical and subapical modiolar attachments. Contracting the platysma can increase negative pressure in the superficial jugular veins of the neck, facilitating circulation.
Dosing The platysma plays a dominant role in the overall contour of the mandibular border and the cervicofacial angle. It is responsible for the presence of horizontal wrinkles found in the vicinity of the modiolus and lateral to the oral commissures (Figure 6). for the horizontal rhytides that appear adjacent to the commissures and are intensified when the corners of the mouth are compressed, 2 u of onabotulinumtoxinA injected 1–2 cm below the inferior margin of the body of the mandible directly inferior to those horizontal wrinkles in 1–3 points 1.5–2 cm apart will diminish them (Figure 6). levy found that he could sharply delineate the
mandibulocervical angle by injecting 2–3 u onabotulinumtoxinA at multiple sites along the upper cervical border of the platysma, just adjacent and inferior to the body of the mandible along the lateral aspect of the neck22
. Injections should be placed posterior to an imaginary
line that is a continuation of the nasolabial fold that traverses the mandible and passes onto the lateral neck and is posterior to the lateral border of the depressor anguli oris and anterior to the belly of the sternocleidomastoid. The total dose for each side of the neck should not exceed more than 15–20 u onabotulinumtoxinA. If there is
38 ❚
Figure 6 55-year-old with lower face platysmal lines owing to ageing and weight loss. Patient is seen before (A, C) and 3 weeks after (B, D) 6 U of onabotulinumtoxin A were injected into the platysma. The mentalis was injected with 5 U of onabotulinumtoxin A, and a hyaluronic acid soft tissue filler was injected deep into the nasolabial folds during the same treatment session
July 2011 |
prime-journal.com
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