The Impact of Upper Face Botulinum Toxin Injections on Eyebrow Height and Forehead Lines: A Randomized Controlled Trial and an Algorithmic Approach to Forehead Injection

No previous study has objectively evaluated the effect of different forehead injection patterns on the eyebrow height and forehead lines. The patients were divided into three groups. Botulinum toxin was injected into both the lateral and medial eyebrow depressors in all groups. The frontalis was injected using either a V-pattern (group 1), a middle horizontal pattern (group 2), or a high horizontal pattern (group 3). Objective eyebrow measurements were performed using standardized preinjection and postinjection photographs. Validated photonumeric scales were used to assess the forehead lines. Fifteen patients (30 eyebrows) were included in each group. In all of the groups, 2 weeks after injection, the brow was lower at all the measured positions, with the exception of the lateral brow edge, which was higher in the three injection patterns. No difference was found when comparing group 1 to groups 2 and 3. The middle forehead injection pattern lowered the eyebrow more than the upper forehead injection pattern. The three techniques improved the forehead lines at rest and with contraction. The forehead lines with contraction were more improved in group 1 compared with both groups 2 and 3. Each forehead injection pattern yielded different results on forehead lines and eyebrow position. Upper forehead injections were less effective on forehead lines but prevented eyebrow ptosis. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.