In the presence of bifurcation, when the patient looks up, the forehead wrinkles have an arched form but when there is no bifurcation, the forehead wrinkles form in straight, connected lines. Patients with arched wrinkles are susceptible to the side effect of angry looking eyebrows where they lift laterally. I advise injecting botulinum toxin toward the lateral eyebrows in such cases. Patients with straight, parallel wrinkles are susceptible to brow ptosis when injections are too close to the brow, therefore, the injection dose and site should be carefully selected in advance.  

Let us take a look at injection techniques.

With the frontal eminence as the middle point, the optimal injection depth above this part is upper muscle layer immediately beneath the dermis, however, in parts below this middle point, the injection depth should be more superficial, at mid to lower dermis layer. The total dose should be 8-10 unit for Botox and 20-25 for Dysport. Inject a total of 15-20 shots at 0.5 unit per site for Botox and 1.25 unit for Dysport (Figure 3).

 

Figure 2. Frontalis muscle of forehead. 

 

To prevent the most common side effects such as eyelid swelling, heaviness and discomfort in opening the eyes, avoid injecting up to 2-2.5 cm above the eyebrow or, the area below the lowest forehead wrinkle. Pay particular attention in patients who habitually lift eyebrows, have ptosis, or have thick and protruding eyelids to avoid side effects.

Injecting deep into the muscle may cause severe paralysis and side effects without any desired benefits. It is advisable to avoid an aggressive approach in the beginning and make additional correction in the follow-up after observing initial response and symmetry.

 

Figure 3. Injection points for forehead. 

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Glabellar Frown Lines and Nasal Root Horizontal Lines (horizontal lines in the glabella and around the nose bridge)

Shallow or deep wrinkles that form due to contraction of the corrugator muscle in the glabella generally form vertically. They may form symmetrically or asymmetrically with one of the vertical lines being more pronounced than others. These vertical wrinkles are often accompanied with horizontal wrinkles that form due to the contraction of the procerus muscle. Removal of shallow wrinkles that form from dermal atrophy is relatively easy but if the subcutaneous fat caves due to long-term muscle contraction causing deep grooves, botulinum toxin may not be sufficient for correction and may need to be combined with dermal filler. It is important to clearly communicate to the patient in advance about the severity of wrinkles and the need to combine dermal filler (Figure 4).

 

-To be continued