title: Eyebrow asymmetry: definition and symmetrical correction using botulinum toxin A.
abstract: BACKGROUND
  Some degree of eyebrow asymmetry is present in many patients who request periorbital rejuvenation, although patients are often unaware of minor asymmetries. There are few parameters for defining eyebrow asymmetry and its incidence in otherwise healthy patients in the literature.
  
  
  OBJECTIVE
  We investigated whether bilateral, symmetric chemodenervation of the primary depressors and elevators of the eyebrows results in a symmetrical standstill of the eyebrows in a neutral position.
  
  
  METHODS
  Measurements of brow height taken in 683 patients who requested reduction of facial rhytids revealed that the minimal amount of asymmetry noticeable to the patients was 2 mm. Between 2002 and 2005, we performed botulinum toxin A injections in a group of 115 patients with eyebrow asymmetry of more than 2 mm who requested aesthetic periorbital rejuvenation; patients with trauma, facial palsy, or previous surgery in the periorbital area were excluded. A total of 30 to 45 units of Botox (Allergan, Irvine, CA) were injected in all patients bilaterally and symmetrically to both brow regions, regardless of their brow height measurements.
  
  
  RESULTS
  All 115 patients completed the study. Mean pretreatment brow height was 18.59 mm at the right lateral canthus and 18.55 mm at the left lateral canthus. After treatment, the mean brow height was 21.91 mm on the right site and 21.89 mm on the left site. The decrease in discrepancy between the right and left brow heights resulting from symmetrical Botox treatment was statistically significant (P < .01). In 83 of 115 patients (72.1%), treatment was successful, with success defined as posttreatment asymmetry of either 0 or 1 mm.
  
  
  CONCLUSIONS
  We propose that bilateral chemodenervation of the primary depressors and elevators of the eyebrows can result in a symmetrical standstill of the eyebrows in the neutral position. The treatment is easy to administer and involves few complications.
authors.affiliation: Private Practice in Istanbul, Turkey.
authors.forename: Tunc
authors.initials: T
authors.lastname: Tiryaki
authors.forename: N Sinem Eroglu
authors.initials: NS
authors.lastname: Ciloglu