| boTulInuM ToxIn A | ARticle
a prominent platysmal band in the lateral neck, this should also be included in the treatment of the ‘nefertiti lift’.
Outcomes for horizontal platysmal wrinkles lateral to the mentum and oral commissures, a treatment with 4–8 u of onabotulinumtoxinA will last 3–4 months. levy, however, reports the effects to last an average of 6 months22
. Injections
of botulinum toxin relax the platysma pars mandibularis, allowing the levators to lift the skin of the lower face. This sharpens and redefines the mandibular border and angle by redraping the skin over the jawline, and elevates the corners of the mouth.
Complications Injecting the platysma pars mandibularis is not easy. If there is diffusion of botulinum toxin A beyond the immediate injection site, the depressor labii inferioris, the orbicularis oris, and other segments of the platysma will be affected, which can adversely impact on the final results. In addition, if the toxin is injected unevenly or taken up by the muscle fibres of the platysma that interdigitate with the lower lip depressors, then an asymmetry and malfunctioning of the mouth and distortion of the lower face will be experienced. other predictable adverse sequelae that can occur are an asymmetric smile, disruption of lip competence causing incontinence of food and liquids, dysarthria, dysphonia and dysphagia. only a minimal amount of low volume toxin should be
injected in the lower face, if predictable and reproducible beneficial treatments are expected. When treating the platysma, keep the injections superficial and far away from the orbicularis oris and depressor labii inferioris.
Horizontal lines and vertical bands of the neck The neck can be an accurate gauge of a person’s age than the overall appearance of his/her face. none of the available invasive surgical procedures have ever satisfactorily and safely eliminated neck lines, platysmal bands and cords for any substantial length of time23
Treatment implications when injecting the jawline and upper platysma
lateral to the mentum and oral commissures can be diminished by intradermal injections of botulinum toxin A along the undersurface of the mandible.
1 Horizontal rhytides just
the upper platysma can blunt the jawline.
intradermal injections along the underside of the mandible and down the lateral neck can sharpen the jawline and lift the lower skin of the face.
2Hyperkinetic fibres of 3Properly placed
platysma should be performed posterior to the origin of the depressor labii inferioris and 2–3 cm inferior to the lower border of the body of the mandible.
4Injections of the upper 5Avoid injecting the
depressor labii inferioris and the deep fibres of the orbicularis oris to prevent an oral sphincter incompetence and a disruption in buccal function.
. Since the 1990s, there has
been the introduction of more aggressive approaches to neck rejuvenation, albeit not as invasive as surgical intervention. These include superficial skin surface altering procedures of chemical or ablative laser resurfacing, and periodic non‑ablative laser or intense pulsed light treatments, thread‑lifting, soft tissue fillers and implants, or regular topical cosmeceutical treatments. However, these procedures fall short of totally eliminating the skin surface damage of solar elastosis, and the pigmentary and textural changes characteristic of photodamage and ageing. Vertical bands and cords may become prominent at an
early age in predisposed individuals. With age, the skin of the neck progressively loses its elasticity, becoming lax and redundant. There is a diminution of soft tissue support, causing the skin of the neck to be susceptible to continuous horizontal creasing, which leads to persistent transverse wrinkles that are perpendicular to the normal vertical contractions of the platysma. When the platysma becomes less elastic, it separates
sternocleidomastoid to avoid difficulty with neck movements and head positioning.
6Avoid injecting the the platysma
comprises two 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 SmAS superiorly in the face.
anteriorly and can be appreciated as two or more divergent bands or folds of skin that extend from the lower margin of the mandible to the medial aspect of the clavicles. Vertical bands and cords develop as the result of a hyperactive platysma attempting to support the ptotic structural changes characteristic of a senescent neck.
Functional anatomy The platysma comprises two 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 SMAS superiorly in the face. It can vary considerably in thickness and extent; in some the platysma may even be absent. 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 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 mandible24, 25
.
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. With maximum contraction the platysma pulls the skin lying over the clavicle upward and wrinkles the skin of the neck in an oblique direction, increasing the diameter of the neck. Some authors emphasise the anatomic variations of the
platysma based on the pattern of decussation of its interlacing fibres as they approach the submental region26–28, 30
. The most common variant seen in
approximately 75% of patients identified as type I, in which the fibres of the platysma interdigitate with its counterpart on the opposite side of the neck 1–2 cm below the chin. In patients with the type II variant (15%), the decussation of fibres occurs at the level of the thyroid cartilage and becomes a unified sheet of muscle up and over the entire submental region. Approximately 10% of patients have the type III variant, presenting as two separate straps of platysma that run parallel up the neck, attaching to the mandible and skin without decussating its fibres28–33 There are two distinctly separate depots of fat in the
.
submental region of the neck that must be taken into account when planning rejuvenation procedures. The more superficial depot is the submandibular fat pad, which lies directly anterior to the platysma in the subcutaneous plane. The other, the subplatysmal fat pad, lies more deeply in the neck, residing behind and posterior to the platysma. Herniation and protrusion of the subplatysmal fat pad in the ageing neck are predicated on the type of anatomic variant of the platysma present, and whether there is a significantly wide separation of the two muscle sheets inferior to the mentum.
Dosing To eliminate most of the dynamic lines of the neck, inject 1–2 u of onabotulinumtoxinA above and below the main horizontal line at points 2–3 cm apart into the deep dermis, rather than the subcutaneous plane, using dilute volumes. Depending on the size of the patient’s neck, no more than 25–35 u of onabotulinumtoxinA should be
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