Indications

Transverse wrinkles of the forehead.

Anatomic Considerations

Contraction of the paired frontalis muscles raises the eyebrows and upper eyelid skin, which produces transverse creases in the forehead. These muscles originate on the galea aponeurotica of the cranium and insert into the skin of the eyebrows. The frontalis muscles are often described as paired muscles that do not meet centrally. Clinically, however, the central position of the forehead is not devoid of wrinkles. Therefore, treatment of the forehead should include injections in the central aspect of the forehead.

The upper face must be assessed both in animation and at rest prior to injection. In women, the brow should lie at or just above the superior orbital rim. In men, it should lie at the bony rim.

Injection Technique

Have the patient raise and lower the brow and assess the extent of muscle movement. The frontalis muscles are located superficially, so the injections should be placed in the superficial subcutaneous tissue. Treat the entire forehead from medial to lateral. As with all BoNTA injections, male patients may require a higher dose. The typical dose ranges from 10 to 20 BU or 30 to 60 DU.

Precautions

The forehead is often described as the most difficult area to inject well. Although treatment of the forehead seems intuitively simple, common errors include overtreatment or poor injection planning. The most important rule of injection is to assess the position of the brows at rest, prior to injection of neurotoxin. Two important conditions of this region must be predetermined: the presence of brow ptosis, and increased resting tone of the muscles, which can mask brow ptosis.

In some patients, horizontal forehead creases are the result of compensation for brow ptosis. These patients often request neurotoxins to improve their deep forehead rhytids. It is important to remember that the frontalis muscles are the only muscles that elevate the brows. If the brow is ptotic, then do not inject the frontalis muscles, as this will worsen the brow ptosis. If injection must be performed on a patient with brow ptosis, plan the injections high in the forehead so that the patient retains some brow elevation movement, or consider undertreating this entire area.

In addition, the frontalis muscles can sometimes show a resting tonic contraction that must be relaxed to determine the resting position of the brow. This may even require the injector to “smooth out” the forehead manually to encourage relaxation of the muscles. Having these patients close their eyes can help relax the frontalis muscles. Once the frontalis muscles are at rest, assess the brow position to determine if the frontalis contraction was masking brow ptosis.

Poor technique in this area can produce an odd-shaped brow. Do not limit the injections to the central brow. Do not assume that the injections cannot extend laterally. If only the center of the brow is treated, the brow will drop medially and elevate laterally, which produces an odd-appearing slanted look, sometimes referred to as the “Mr. Spock,” or “Mephisto (devilish) sign.” A lateral browlift can be obtained by using this technique, but proceed with caution in this area to avoid an overly slanted medial brow.