Extra facial esthetic indications of botulinum toxin: A review

Vertical bands

The platysma muscle is a large sheet of subcutaneous muscle. It extends three finger breadths above and parallel to the lower border of the mandible, one finger breadth posterior to the depressor anguli oris, and all the way down over the cervicomental angle and anterior neck to the upper border of the clavicle, and posteriorly to the anterior border of the sternocleidomastoid.^[5]

Platysmal contraction blunts the cervicomental angle. A lax platysma shall hence result in an obscure, ill-defined jawline. In addition, bands formed on its contraction, known as platysmal bands, are the result of this persistently active muscle trying to support the sagging deeper neck and floor of the mouth structures. The anterior edges of the muscle lose tone and separate over time to protrude anteriorly forming the “turkey neck” deformity.^[6]

Injection technique

The vertical neck bands are made prominent by asking the patient to clench the teeth and depress the lateral oral commissure [Figure 1]. An individual band is grasped between the thumb and index finger of the non-dominant hand and 1–2 U of BTX A (100 U BTX A is diluted with normal saline of 2.5 mL) is injected 1.5–2 cm apart directly into the belly of the muscle. Three to five sites per band are usually enough. A total of 15–20 U BTX A are recommended for the neck.^[7]

Close

Figure 1:

Platysma bands: (a) Platysma anatomy with injection points (yellow dots) and (b) surface anatomy with injection points (red dots).

Export to PPT

Horizontal lines or venus rings

Horizontal neck lines present as linear depressions or furrows, which occupy the anterior half of the neck [Figure 2].^[8] These form as a result of the pleating of overlying skin perpendicular to the underlying platysma. The BTX has been used to relax the platysma and smoothen neck bands and lines. The horizontal neck wrinkles are not entirely caused by aging, as they are often observed in children and young adults.^[9,10] However, age-related skin laxity often worsens these lines.^[9]

Close

Figure 2:

Horizontal neck lines: 1–2 U of botulinum toxin A is injected at 8–10 points (red dots) 1–1.5 cm apart.

Export to PPT

Microbotox

Microbotox is a term coined in 2001 to describe the technique of delivering multiple intradermal or subdermal injections of diluted onabotulinumtoxinA into the overlying skin envelope and superficial layer of the facial and neck muscles.^[12,13]

Technique of injection

To prepare the Microbotox solution, a 100 U vial of BTX A is reconstituted with 2.5 mL of saline (standard dilution). Further, 0.5 mL of BTX A is withdrawn from this vial and a further 0.5 mL of lidocaine (0.5%) with or without adrenaline is then drawn into the syringe to make it up to 1 mL volume. This gives a concentration of 20 units of BTX per mL.

If the platysma is bulky (thicker necks): 28 units/ml. Prepare by drawing 0.7 ml (28 units) from a vial with standard dilution and top it up with 0.3 ml lidocaine (0.5%) with or without adrenaline.^[12]

The injection is given in a semi-reclined position with the neck arched upward to make the skin taut. Additionally, stretching between finger maintains the tautness. A 30–32 G needle is used with the bevel pointed downward, and BTX A is injected 8–10 mm away with extreme caution to just penetrate the needle into the skin as superficially as possible [Figure 3].

Close

Figure 3:

Microbotulinum toxin: (a) Surface marking for platysma on one side, (b) superficial injection blebs visible upon toxin infiltration, and (c) neck with injection points (yellow dots) for reference on the entire neck and inferior border of mandible.

Export to PPT

In the average lower face and neck, 1 mL of microbotox is used to cover the entire area of one-half of the lower face and neck.

An alternative to this technique has been described by Calvani et al. as the “superficial injection needling botulinum” technique. A higher concentration of onabotulinumtoxinA (50 U in a 0.8-mL syringe) is delivered intradermally using an electrical needling pen to a depth of 3–3.5 mm.^[14]

Mechanism of action of BTX A for androgenetic alopecia

The BTX A relaxes the muscle thus reducing pressure on the musculocutaneous and perforating vasculature, thereby increasing the blood supply and transcutaneous pO₂. This increased blood flow can also lead to the washing out of accumulated DHT, thereby reducing the signal for miniaturization of hair follicles. Furthermore, a high concentration of oxygen can stimulate the hair follicle into the growth phase resulting in hair regeneration.^[21,22]

Technique of injection

The BTX A 100 U diluted in 1 mL normal saline is injected intramuscularly at 30 different sites; 5 U at each site resulting in a total of 150 U in the frontalis, occipitalis, temporalis, and periauricular muscles [Figure 4],^[22] 30–32G needles are preferred.

Close

Figure 4:

Androgenetic alopecia: 30 points (red dots) to be injected with 5 U of botulinum toxin A at each point. The muscles that are targeted are occipitofrontalis, temporalis, and periauricular muscles.

Export to PPT

Complications

None reported, but suboptimal results may be experienced, as this modality does not tackle the androgenetic pathway.

Practice tip

Ensure adequate topical anesthesia, as these volumes are painful on the scalp.

Technique of injection

Assess the degree to which the gastrocnemius muscle is contributing to the calf bulge. A pinch test to differentiate it from fat bulges is useful.^[26] Determine the calf bulge type; a uniform or medial bulge due to the relevant gastrocnemius head bulk. The BTX A in 2.5 mL dilution is injected in the tip-toe prone position using a 1-inch 23 G needle. Authors prefer using a 24 G IV cannula needle, which provides enough depth and is less painful. Although numerous injection points have been described targeting the most bulky area and avoiding underdosing is the common rule^[27] [Figure 5]. Dose depends on the bulk of muscle hypertrophy, and usually, 30–200 U are injected on each side.^[25] Liu et al., have proposed a scoring system to determine the bulk volume and pattern to calculate the total dose needed.^[28] Three to six intramuscular injections 1.5–2 cm apart are recommended to be administered in the most prominent part of the medial and lateral head of the gastrocnemius.

Close

Figure 5:

Calf slimming effect: (a) Anatomy of gastrocnemius with injection points (yellow dots) for reference, and (b) three to six intramuscular injections of botulinum toxin A is given 1.5–2 cm apart administered into the most prominent part of gastrocnemius (red dots).

Export to PPT

Complications

At higher doses, it can lead to calf muscle weakness resulting in gait disturbance and fatigue after walking or running.

Practice tip

• Adequate topical anesthesia must be used. Use a thinner cannula to ensure adequate depth and less painful injections

• Gastrocnemius is a bulky muscle, avoid underdosing.

Technique of injection

Each soleus muscle is injected with 50 units of BTX A in 1.2 mL diluent, as an intramuscular injection on both sides of the ankle [Figure 6]. A total dose of 100 units of BTX was administered to each ankle.^[30]

Close

Figure 6:

Ankle contouring: (a) Anatomy of soleus with injection points (yellow dots) for reference and (b) three to six intramuscular injections of botulinum toxin A is given on both sides of each soleus muscle (red dots).

Export to PPT

Complications

If a higher dose of toxin is used, there may be ankle weakness and difficulty in walking and running.

Practice tip

• Attempt this indication in combination with gastrocnemius

• This muscle lies deeper into the gastrocnemius. It contributes to the lateral calf/ankle bulk and is accessible and injected along its lateral borders.

Mechanism of action

The BTX helps to relax the hypertrophied trapezius muscles creating smooth contours, which in turn helps to improve the neck length.

Technique of injection

The upper border of the trapezius is marked out. The most prominent strip of the upper portion of the trapezius muscle is chosen [Figure 7]. Anatomical studies on cadavers and thereafter their clinical application have demonstrated a common area on the muscle that provides the best results for toxin administration. Lee et al. marked out a line from the occipital protuberance to the lateral most portion of the acromion, on the superior most portion of trapezius and divided it into fifths. The area covered by the fourth region has been shown to contain the maximum number of neuromuscular junctions followed by the third region.^[32] Bae et al. arrive at a similar region on a line joining the seventh spinous process to the acromion.^[33] Toxin injection in this region is the most beneficial. Five to six points, 2 cm apart are injected with 5–10 U on each side, for a total of 30–50 U of BTX A. Depth of injection recommended is 13 mm with a 27–30 G needle^[34,35] [Figure 5]. Ultrasound guidance may also be used to determine the most hypertrophied area of the muscle.^[36]

Close

Figure 7:

Shoulder slimming effects: (a) Anatomy of trapezius with injection points (yellow dots) for reference; (b) botulinum toxin A is injected at five or six points (red dots) 1-2 cm apart, each point receiving 5-10 U of the toxin.

Export to PPT

Complications

If the BTX is injected extremely close to the neck, it can lead to neck muscle weakness.

The extreme lateral injection point can lead to diffusion of BTX to the origin of the deltoid muscle, which may cause difficulty in shoulder joint extension.

Regular injection of BTX into the muscle leads to neurogenic atrophy with muscle mass loss.^[35]

Practice tip

• Mark the bulkiest portion of the trapezius from the frontal view

• Mark the injection points from the posterior view.

• Avoid the descending margin of the trapezius.