Understanding the Anatomy Behind Frown Lines

Understanding the anatomy behind frown lines is crucial for effective treatment.

The vertical lines of the glabella are caused by the contraction of the paired corrugator supercilii muscles, while the horizontal lines are due to the centrally located procerus muscle.

• Corrugator Supercilii Muscles: These muscles originate on the supraorbital ridge of the frontal bone and insert into the skin above the middle third of the eyebrow.
• Procerus Muscle: This muscle originates on the nasal bone and inserts into the skin of the glabella or mid-forehead.

Despite the seemingly straightforward anatomy, there are subtle variations that can be observed during facial movement.

There are two distinct patterns of corrugator positioning: either straight along the brow or more vertically oriented in a V-shape.

Because of these variations, injectors should not rely on a single technique. Instead, they should visualize the underlying muscles and their impact on wrinkle formation during facial animation.

Injection Technique

When it comes to the injection technique, here are some key points to keep in mind:

1. Anesthesia: Topical anesthesia can be used, but this injection is usually well tolerated without it.
2. Preparation: Before injecting, ask the patient to frown. This helps you visualize the size, strength, and location of the procerus and corrugator muscles. The lateral extent of the corrugator muscles can be seen by the dimpling of the skin, as these muscles insert laterally into the skin.
3. Dosage: Common doses in this region range from 20 to 30 Botox Units (BU) or 50 to 80 Dysport Units (DU). However, injector experience shows that some patients may require as little as 10 units, while others (often men) may need substantially more.
4. Injection Placement: Place injections 1 cm above the superior orbital rim to minimize the risk of upper eyelid ptosis. Inject into the muscle belly and avoid “bumping” the periosteum, as this can sometimes lead to post-injection headaches.

Stay Safe

Injecting in this area requires careful attention to minimize risks. One potential side effect is upper lid ptosis, which can appear up to 2 weeks after the injection and may last for 2 to 4 weeks. To reduce this risk, ensure injections are placed 1 cm above the superior orbital rim.

Post-Injection Instructions

While there is no clinical data indicating that post-treatment instructions can decrease ptosis or improve results, some physicians provide the following guidelines to their patients as a precaution:

• Avoid bending over, pressing on the injection sites, or lying down for 4 hours after the treatment.
• Refrain from exercising on the day of the injection.
• Do not actively move the injected muscles for 90 minutes after the treatment.

To minimize the risk of bruising and maximize the effectiveness of the treatment, consider the following post-injection instructions:

• Avoid exercising immediately after the injection, as this can potentially accentuate bruising.

Risks

Diffusion into Eyelid: Product diffusion into the eyelid can affect the levator palpebrae superioris muscle, possibly leading to transient ptosis (drooping eyelid).

Practical Tips For Injection

Here are some tips for effective injection technique:

1. Assess Muscle Size and Shape: Ask the patient to frown to assess the size and shape of the muscle. Tailor the treatment based on individual anatomy.
2. Extend Injections Laterally: Ensure injections extend far enough laterally to treat the entire extent of the corrugator muscles.
3. Consider Fillers for Deep Wrinkles: For deep wrinkles in this region, filler injections may be necessary in addition to neurotoxin treatment.
4. Consistent Retreatment: Regular treatments of the glabella can lead to the patient "unlearning" to move their brow, potentially improving wrinkles and extending the interval between injections.
5. Placement Technique: Placing the thumb along the orbital rim during injection may help reduce the risk of product diffusion toward the levator palpebrae superioris muscle.