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Cosmetic use of Botox
Aging is associated with the development of lines and wrinkles caused by actinic damage, gravitational effect, sleep lines, and muscular action. Mimetic facial musculature may undergo hypertrophy secondary to hyperfunctional pull. Botox injections reduce facial lines caused by hyperfunctional muscles. They also are used to contour aspects of the face such as the brows.
General considerations
Injection techniques often vary among practitioners and over time. Some practitioners use electromyogram (EMG) guidance routinely, although most reserve it for treatment of those in whom Botox does not produce a response. Patients usually notice a clinical effect 1-3 days following injection, and the effect is maximal by 1-2 weeks. Some diffusion of toxin occurs. A 10-unit injection into the frontalis muscle produces a circular area of paresis with a radius of approximately 1.5 cm. Space injections apart appropriately, and do not place injections too close to muscles in which weakness is to be avoided.
Adverse effects of injection include minimal ecchymosis and bruising. When not contraindicated, patients should avoid platelet inhibitors, including aspirin and nonsteroidal anti-inflammatory drugs, for 7-14 days prior to injection.
Set realistic expectations. The benefits usually last 3-6 months and then resolve.
Horizontal forehead lines
Performing Botox injections to treat horizontal forehead lines is relatively easy, and the result usually is quite satisfying. Treatment can include injections for glabellar frown lines when appropriate.
Anatomy
The frontalis muscle elevates the eyebrows and the skin of the forehead. The fibers of the frontalis are oriented vertically, and wrinkles of the forehead are oriented horizontally. The frontalis muscle originates on the galea aponeurotica near the coronal suture and inserts on the superciliary ridge of the frontal bone and skin of the brow, interdigitating with fibers of the brow depressors (ie, procerus, corrugator supercilii, orbicularis oculi muscle; see Image 5). The medial fibers usually are more fibrous than the lateral fibers, thus requiring less toxin for paralysis. Avoid total paralysis of the frontalis, since this is likely to cause brow ptosis and loss of expression. Injection too close to the lateral eyebrow can cause lateral eyebrow ptosis.
Technique
Multiple injections of small amounts of toxin create weakness without total paralysis. Inject 3-5 sites on each side of the mid line, usually using 2 units (1-3 U) per site. Separate sites by 1-2 cm. Choose an initial injection site approximately 1 cm above the eyebrow vertical to the medial canthus. Additional sites diverge laterally and upward to the hairline in a "V" configuration, often for a total of 3 sites. Additional sites (1-3) can be added in the mid line or more laterally (1-2) depending on individual and clinical response.
If wrinkles extend to the temporal region, lateral injections can be performed. Use caution to prevent injecting lateral to the lateral canthus to avoid inhibiting temporalis function. Use caution when injecting patients in whom the hyperfunctional frontal lines support a ptotic upper eyelid.
Injections of the upper face and periocular region usually are performed with the patient seated, and the patient is asked to remain upright for 2-3 hours to prevent spread of toxin through the orbital septum.
Glabellar frown lines
Glabellar frown lines are the most common reason for cosmetic injection of Botox (see Image 4).
Anatomy
Facial rhytids and folds in this area result from action of the depressor muscles (ie, corrugator supercilii, depressor supercilii, orbicularis oculi, procerus; see Image 5). The corrugator superciliaris, medial orbital portion of the orbicularis oculi, and more vertically oriented fibers of the depressor supercilii produce the vertical lines of the glabella.
The corrugator muscle is a brow adductor moving the eyebrow downward and medially. It arises from the nasal bone just above the rim of the orbit medially and extends laterally and upward, inserting in the skin above the middle of the eyebrow. It lies deep to the frontalis, procerus, and orbicularis oculi muscles. The medial fibers of the orbicularis oculi originate from the medial orbital rim anterior to the origin of the corrugator. The fibers interdigitate with fibers of the frontalis, procerus, and corrugator muscles. The depressor supercilii originates from the nasal process of the frontal bone and inserts into the skin at the medial aspect of the eyebrow.
The vertically oriented procerus muscle, which originates from the upper nasal cartilage and the lower nasal bone, produces the horizontal lines of the glabella and nasal root. It inserts into the skin between the brows and the frontal belly of the occipitofrontalis. Its fibers interdigitate with those of the orbicularis, frontalis, and corrugator muscles.
Technique
Usually, 5 sites are injected with 4-6 units each for an average total dose of approximately 25 units. One site on each side is used to inject the corrugator, one site on each side is used to inject the orbicularis oculi and depressor supercilii, and one site is used to inject the procerus in the mid line.
The patient is asked initially to frown and scowl, and the target muscles are palpated. Place the first injection into the belly of the corrugator muscle. Insert the needle at the origin of the corrugator fibers just above the medial canthus and superciliary arch until bone is felt, and then withdraw it slightly. Advance the needle within the belly of the muscle upward and lateral as far as the medial third of the eyebrow, 1 cm superior to the orbital rim. Inject 4-6 units as the needle is withdrawn.
The next site is approximately 1 cm above the upper medial aspect of the supraorbital ridge. Advance the needle slightly in a vertical direction toward the hairline. Inject 4-6 units into the orbicularis oculi and depressor supercilii as the needle is withdrawn. Repeat these injections on the contralateral side.
Place the last injection into the belly of the procerus to eliminate the horizontal lines at the root of the nose. Inject 4-6 units at a point where 2 lines drawn at 45° from the medial aspect of the eyebrows converge in the center of the nasal root, just superior to the horizontal plane of the medial canthi. To avoid resultant accentuation of eyebrow arching in men, inject an additional 4-6 units 1 cm above the supraorbital prominence vertical to the mid point of the eyebrow.
In 1998, a dose/response study by Hankins et al of 46 women receiving Botox for glabellar wrinkles found an effective starting dose from 2.5-4 units per injection site (12.5-20 U total).
A glabellar "spread test" may be performed prior to injection by spreading the glabellar wrinkles apart with the thumb and index fingers. This may allow an estimate of the expected benefit from Botox injection. Patients with thick sebaceous skin and deep dermal scarring that are not improved with manual spreading usually respond poorly to botulinum toxin injections. EMG guidance may provide valuable information when initial injections prove unsatisfactory.
Lateral canthal lines
Aging and photodamage cause much of the wrinkling in this area. However, the component of hyperfunctional contraction of the lateral aspect of the orbicularis oculi is targeted for improvement with Botox injections.
Anatomy
The lateral fibers of the orbicularis oculi are arranged in a circular pattern around the eye. Contraction of these fibers produces wrinkles that extend radially from the region of the lateral canthus.
Technique
Perform 3 or 4 subcutaneous injections approximately 1 cm lateral to the lateral orbital rim using 2-3 units per injection site (for a total of 6-12 U per side). Space sites 0.5-1 cm apart in a vertical line or slightly curving arch. Doses that are too high or injections that are too medial can lead to eyelid ptosis or diplopia.
Other cosmetic uses of Botox injections of the face
Temporal brow lift
With age, the lateral eyebrow typically becomes ptotic before the medial aspect. The lateral brow is more affected by the gravitational descent of the temporal soft tissue mass and the downward force of the corrugator supercilii and orbicularis oculi muscles. Temporal brow lift can be achieved by Botox injections into the lateral brow depressors. Ahn et al treated patients seeking elevation in eyebrow height with 7-10 units of Botox injected into the superolateral portion of the orbicularis oculi below the lateral third of the brow. Mean brow height increased 1.0 mm at the mid pupil and 4.8 mm at the lateral canthus (p=0.038 and 0.0001, respectively). Injecting superior and lateral to the orbital rim minimized the potential for ptosis.
Levator labia superioris
Contraction of this muscle is observed when an individual "scrunches" his or her nose, and hyperfunctional contraction often confers a "mad dog" appearance to the face. This muscle can be injected with 2-5 units of Botox on each side of the nose lateral to the nasion.
Nasal flare
Several patients with undesirable nasal flare have been treated successfully with serial Botox injections.
Mental crease
Reduction of a prominent mental crease can be achieved by injection of 5-10 units of Botox into the point of the chin.
Facial asymmetry
Injections of Botox can improve facial asymmetry and synkinesis. The asymmetry of residual unilateral paresis can be reduced by judicious injection of normal muscles on the unaffected side. Hyperkinesis from aberrant degeneration can be reduced by injection of hyperkinetic muscles.
Upper lip wrinkling
Optimally treat multiple fine wrinkles using a filler substance such as injectable collagen or by middepth or deeper resurfacing. These fine wrinkles do not respond well to Botox injections, and the upper lip is sensitive to paresis. However, botulinum toxin injections may be used in individuals with 2 or 3 deep wrinkles. Small doses of botulinum toxin (0.5-1 U per wrinkle) may be administered, injected superficially rather than deeply. Avoiding weakness of the upper lip is important.
Depressor anguli oris
To weaken the depressor anguli oris, which is the underlying muscle of the downturn at the corner of the mouth, 2-3 units of botulinum toxin may be injected. Instruct the individual to forcibly pull down the corners of the mouth; the depressor anguli oris can be felt inferior to a point 1 cm lateral to the commissure.
Nasolabial folds
Carruthers and Carruthers, attempting to soften the nasolabial fold, injected low doses (2-3 U) of Botox in the levator labii superioris alaeque nasi. EMG localization of the muscle was used. Some of the individuals who had softening of the folds showed lengthening of the upper lip. In general, achieving a good result in attempting to soften the nasolabial fold is difficult.
Adjunctive use of Botox injections
Botox injections may be used to provide presurgical chemodenervation of the brow depressor muscles, giving better results with surgical repositioning of the brow. Pretreatment of crow’s feet allows the surgeon to better define the incision line within the confines of the bony orbital margin.
Contraindications to Botox injections
Contraindications include prior allergic reaction, injection into areas of infection or inflammation, pregnancy (category C - safety for use during pregnancy has not been established), or breastfeeding. Women who inadvertently were injected during pregnancy thus far have had uneventful deliveries, and to date no teratogenicity has been attributed to botulinum toxin. Nonetheless, it is a category C medication, and delay of injections is recommended until pregnancy is complete and breastfeeding has ended.
Relative contraindications
Treat patients with diseases of the neuromuscular junction (eg, myasthenia gravis) cautiously because underlying generalized weakness can be exacerbated, and local weakness at injection sites can occur more than otherwise expected. Some medications decrease neuromuscular transmission and generally should be avoided in patients treated with botulinum toxin. These include aminoglycosides, penicillamine, quinine, and calcium channel blockers.
Other considerations
Single-fiber EMG studies have detected neuromuscular changes far removed from injection sites. This likely reflects hematogenous spread of a small amount of toxin and is not of known clinical significance. Avoid intravascular injections because diffuse spread of large amounts of toxin can mimic the symptoms of botulism.
Complications
Generalized idiosyncratic reactions are uncommon, generally mild, and generally transient. These include nausea, fatigue, malaise, flulike symptoms, and rashes at sites distant from the injections. Untoward sequelae caused by percutaneous injection include pain, edema, erythema, ecchymosis, headache, and hypesthesia. These also are generally mild and transient. The most common meaningful adverse effect is unwanted weakness. Fortunately, unwanted weakness caused by the action of the toxin usually resolves in several months and in some patients in a few weeks, depending on the site, strength of the injections, and the muscles made excessively weak.
Carefully counsel patients who depend on emotive expression, such as actors and politicians, about a potential reduction in expression. Excess weakness following frontalis injection may cause paralysis rather than weakening of the muscle. Patients report they appear masklike and their brow feels heavy. If brow ptosis occurs, a hooded appearance may be present, and occasionally vision may be partially obstructed. Therefore, avoiding use of overly large doses and restricting injections to 1 cm above the eyebrow are important. If the lateral fibers of the frontalis have not been injected appropriately, a quizzical appearance may result in which the lateral brow is pulled up while the central brow is lowered. Inject a small amount of toxin into the lateral fibers to treat this.
Note the clear distinction between hyperfunctional brow lines with no underlying brow ptosis versus frontalis contraction to elevate ptotic brows. If botulinum toxin is used in the latter case, brow ptosis is likely. The brow depressors generally can be paralyzed to treat glabellar lines. However, ptosis of the upper eyelid is a common complication following injection in this region. This may occur as late as 2 weeks after injection. Ptosis is caused by migration of toxin through the orbital septum. Patients often are instructed to remain in an upright position for 3-4 hours following injection and to avoid manual manipulation of the area. Active contraction of the muscles under treatment may increase the uptake of toxin and decrease its diffusion.
To avoid ptosis, place injections 1 cm above the eyebrow and do not cross the midpupillary line. Ptosis can be treated with apraclonidine 0.5% eyedrops. This is an alpha2-adrenergic agonist, which causes Müller muscles to contract. Apraclonidine is contraindicated in patients with documented hypersensitivity. Phenylephrine (Neo-Synephrine) 2.5% can be used when apraclonidine is not available. Neo-Synephrine is contraindicated in patients with narrow-angle glaucoma and in patients with aneurysms. Use 1-2 drops 3 times daily until ptosis resolves.
Weakness of the lower eyelid or lateral rectus can occur following injection of the lateral orbicularis oculi. If severe lower lid weakness occurs, an exposure keratitis may result. If the lateral rectus is weakened, diplopia results. Treatment is symptomatic. Avoid these complications by injecting at least 1 cm lateral to the lateral canthus and above the zygomatic arch.
Injection of platysma muscles can result in dysphagia from diffusion of toxin into muscles of deglutition. When this occurs, it usually lasts only a few days or weeks. Some patients may require soft foods. Although a swallowing weakness does not herald systemic toxicity, if it is severe, patients may be at risk of aspiration; seek consultation.
Some patients experience neck weakness, which is especially noticeable when attempting to raise the head from a supine position. This occurs after weakening of the sternocleidomastoid muscles, either from direct injection or diffusion. This is more common in women with long thin necks.
Avoid these adverse effects by using the lowest effective doses and precisely placing toxin into the platysma.
Therapeutic failure
Some patients do not respond to injections and, having never previously responded, are designated as primary nonresponders. Many reasons may lead to a lack of response. Patients with rhytids that are not dynamic in origin (eg, photodamage, age-related changes) do not respond. Possibly, the injection technique was inadequate or the toxin denatured. Theoretically, some patients may have neutralizing antibodies from prior subclinical exposure, or individual variations in docking proteins may exist. A test dose of 15 units in the frontalis muscle should indicate whether the patient experiences a physiologic response (weakness) to toxin.
Secondary nonresponders respond initially but lose the response on subsequent injections. Most of these patients may have developed neutralizing antibodies.
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