title: Effect of Weakening of Ipsilateral Depressor Anguli Oris on Smile Symmetry in Postparalysis Facial Palsy.
abstract: OBJECTIVE
  Aberrant depressor anguli oris (DAO) activity may arise after recovery from acute facial paralysis and restrict movement of the oral commissure.
  
  
  OBJECTIVE
  To quantify the degree to which DAO inhibition affects smile dynamics and perceived emotional state.
  
  
  METHODS
  In this prospective, pretest-posttest study performed at an academic tertiary referral hospital, patients with unilateral postparalysis facial palsy were studied from January 16 through April 30, 2016.
  
  
  METHODS
  Local anesthetic injection into the ipsilateral DAO.
  
  
  METHODS
  Healthy- and paretic-side commissure displacements from the midline lower vermillion border referenced to the horizontal plane were calculated from random-ordered photographs of full-effort smile before and after injection, and random-ordered hemifacial photographs of the paretic side were assessed as expressing positive, negative, or indiscernible emotion.
  
  
  RESULTS
  Twenty patients were identified as having unilateral postparalysis facial palsy with marked synkinesis of the ipsilateral DAO. Patient mean age was 46 years (range, 24-67 years), with a male to female ratio of 1:3. Mean paretic-side commissure displacement increased from 27.45 mm at 21.65° above the horizontal plane to 29.35 mm at 23.58° after DAO weakening (mean difference, 1.90 mm; 95% CI, 1.26-2.54 mm; and 1.93°; 95% CI, 0.34°-3.51°; P < .001 and P = .20, respectively). Symmetry of excursion between sides improved by 2.00 mm (95% CI, 1.16-2.83 mm; P < .001) and 2.71° (95% CI, 1.38°-4.03°; P < .001). At baseline, observers assessed 7 of 20 paretic hemifaces (35%) as expressing positive emotion; this proportion increased to 13 of 20 (65%) after DAO weakening (P = .03).
  
  
  CONCLUSIONS
  Ipsilateral DAO weakening results in significant improvements in smile dynamics and perceived expression of positive emotion on the paretic hemiface in postparalysis facial palsy. A trial of DAO weakening should be offered to patients with this disfiguring complication of Bell palsy and similar facial nerve insults.
  
  
  METHODS
  3.
authors.affiliation: Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston.
authors.forename: Nate
authors.initials: N
authors.lastname: Jowett
authors.affiliation: Health Sciences and Technology Program, Harvard Medical School and the Massachusetts Institute of Technology, Boston.
authors.forename: Ronit
authors.initials: R
authors.lastname: Malka
authors.affiliation: Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston.
authors.forename: Tessa A
authors.initials: TA
authors.lastname: Hadlock
mesh_terms: D000328:Adult; D000368:Aged; D020330:Bell Palsy / Q000209:etiology / Q000503:physiopathology*; D005152:Facial Muscles / Q000187:drug effects / Q000503:physiopathology; D005158:Facial Paralysis / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008012:Lidocaine / Q000008:administration & dosage*; D008046:Lip / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D018908:Muscle Weakness / Q000188:drug therapy* / Q000503:physiopathology*; D012904:Smiling / Q000502:physiology*; D046608:Synkinesis / Q000188:drug therapy* / Q000503:physiopathology*
chemical_list: D008012:Lidocaine