title: Efficacy of botulinum toxin type a after topical anesthesia.
abstract: OBJECTIVE
  To determine whether the use of topical anesthesia has an impact on botulinum toxin type A (BTX-A) efficacy.
  
  
  METHODS
  Forty patients (20 receiving BTX-A for facial cosmetic rhytid reduction and 20 for benign essential blepharospasm) were evaluated in a double-blind, randomized, triple-crossover study at 2.5- to 4.5-month intervals. The discomfort and efficacy of BTX-A injections after betacaine application to half the face (random assignment) were compared against the discomfort and efficacy of a placebo ointment on the other half of the face. This was followed by cryoanalgesia to the entire face.
  
  
  RESULTS
  Patients ranged from 27 to 81 years of age (mean, 53 years), and 34 were female. Of the 120 total injection comparisons, a better BTX-A effect on one side of the face was reliably identified by 80% and 77% of blepharospasm and cosmetic patients, respectively, with the placebo-treated side providing better BTX-A effect approximately 90% of the time (p < 0.001). Patients reported a more painful side during injection in just 18 of the 120 trials, and only 1 of 40 patients believed the administration of analgesia was worth the trouble.
  
  
  CONCLUSIONS
  Pretreatment with topical betacaine followed by skin cooling seems to have a deleterious impact on BTX-A effect without a significantly beneficial patient-perceived reduction in injection discomfort.
authors.affiliation: Plastic Eye Surgery Associates, PLLC, Houston, Texas, USA.
authors.forename: Mirwat S
authors.initials: MS
authors.lastname: Sami
authors.forename: Charles N S
authors.initials: CN
authors.lastname: Soparkar
authors.forename: James R
authors.initials: JR
authors.lastname: Patrinely
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Hollier
authors.forename: Larry H
authors.initials: LH
authors.lastname: Hollier
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000772:Anesthesia, Local / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001764:Blepharospasm / Q000188:drug therapy*; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D015361:Rhytidoplasty / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D000779:Anesthetics, Local; D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A