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

Sir: We read with interest the recent article by Jabbour et al. (Plast Reconstr Surg. 2018;142:121–1217).1 We appreciate the authors’ excellent work. However, there are several points attracting our attention, and we would like to express some opinions. The authors objectively evaluated the effect of different forehead injection patterns on the eyebrow height and forehead lines: a V-pattern, a middle horizontal pattern, and a high horizontal pattern. Botulinum toxin was concurrently injected into both the lateral and medial eyebrow depressors in all groups in the authors’ study. However, we found that the authors did not clearly explain the intention of the eyebrow depressor injection in all groups, which might factually influence the measured results of the eyebrow height if this was not performed. Furthermore, the authors put forward an algorithmic approach to upper face botulinum toxin injection and pointed out that the upper forehead horizontal injection pattern was mainly indicated in two specific clinical scenarios, the premise of which was concurrently injected with lateral and medial eyebrow depressors. We are confused regarding the indications of this combined application for a young patient with only minimal wrinkles limited to the upper forehead. From our perspective, eyebrow ptosis can generally be avoided by injecting no closer than 1 cm above the bony orbital rim in the midpupillary and using lower doses in the frontalis.2 For designated older patients, the authors pointed out the following: (1) injections into the whole forehead should be prohibited; and (2) although it is necessary to discuss regions of the face individually, treating areas of the face in isolation does not yield the best possible outcomes for patients1 (we are puzzled regarding the reduced small doses just injected in the most cephalic part of the forehead for older patients); and (3) if these patients’ cosmetic concern was brow elevation, they could be classified into the brow elevation without forehead lines treatment group. In addition, the authors pointed out that elevation of the eyebrows is mainly caused by frontalis contraction and not by paralysis of the eyebrow depressors, and considered that higher forehead injections allowed a residual lower frontalis contraction that prevented the severe eyebrow depression observed with lower forehead injections. However, the authors had concurrently injected into both the lateral and medial eyebrow depressors in the study. Thus, it was not accurate to state that the avoided eyebrow depression resulted from residual lower frontalis contraction solely. The weakened depressors also contributed to the final results, which should not be neglected in the authors’ study. Actually, out-of-balance force between the frontalis muscle and antagonistic muscles would result in eyebrow disturbance.3 DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. No funding was received for this communication. Zhen Zhai, M.D.Zuoliang Qi, M.D., Ph.D.Department No. 16Plastic Surgery HospitalChinese Academy of Medical Sciencesand Peking Union Medical CollegeBeijing, People’s Republic of China[email protected]