Pathophysiology

Eyebrow ptosis is something that can be deeply upsetting and socially impactful for the patient it has happened to. It commonly presents as a reduction in the space between the brow arch and eyelid, causing a heavy feeling over the forehead area and an angry, concerned or tired look.

Women find this difficult, putting make up on will be hindered and may not give the desired look.

The main cause of brow ptosis is as a result of over relaxation of the brow elevators.

• The frontalis muscle supports at rest and raises brows
• Glabella complex pulls down
• Orbicularis oculi also pulls down

When the dose and placement of toxin is disproportionate the brows will drop.

When the aim is to reduce movement with botulinum, this is easily achieved, however as a result we can also reduce support too, this is an undesired side effect of toxin. As a result, the skin of the forehead can lower, causing one of three different outcomes.

• Lateral drop causing a sense of tiredness when the skin compresses into the eyes. The brow shape can become flatter or depressed.
• The brows can become arched or angles in a medical drop. The lateral elevator muscles lift but the medical muscles weakened will drop
• Both could occur together, giving a look of tiredness or anger

Higher doses and injecting lower down in the frontalis muscle will also be a risk factor for brow ptosis or injecting more laterally over the frontalis.

Variants of patient selection will also play a role, there are 4:

• More mature patients
• Very hyperdynamic foreheads, lots of movement in many directions
• Skin is a continuous surface to eyelashes, not much differentiation in muscle movement

Bulky or heavy forehead