title: Treatment of lateral epicondylitis with botulinum toxin: a randomized, double-blind, placebo-controlled trial.
abstract: BACKGROUND
  Lateral epicondylitis is a common condition for which botulinum toxin has been reported to have a therapeutic role in uncontrolled studies.
  
  
  OBJECTIVE
  To determine if an injection of botulinum toxin is more effective than placebo for reducing pain in adults with lateral epicondylitis.
  
  
  METHODS
  Randomized, double-blind, placebo-controlled trial conducted from September 2002 to December 2004.
  
  
  METHODS
  Outpatient clinics at a university hospital and a district hospital in Hong Kong.
  
  
  METHODS
  60 patients with lateral epicondylitis.
  
  
  METHODS
  The primary outcome was change in subjective pain as measured by a 100-mm visual analogue scale (VAS) ranging from 0 (no pain) to 10 (worst pain ever) at 4 weeks and 12 weeks. All patients completed post-treatment follow-up.
  
  
  METHODS
  A single injection of 60 units of botulinum toxin type A or normal saline placebo.
  
  
  RESULTS
  Mean VAS scores for the botulinum group at baseline and at 4 weeks were 65.5 mm and 25.3 mm, respectively; respective scores for the placebo group were 66.2 mm and 50.5 mm (between-group difference of changes, 24.4 mm [95% CI, 13.0 to 35.8 mm]; P < 0.001). At week 12, mean VAS scores were 23.5 mm for the botulinum group and 43.5 mm for the placebo group (between-group difference of changes, 19.3 mm [CI, 5.6 to 32.9 mm]; P = 0.006). Grip strength was not statistically significantly different between groups at any time. Mild paresis of the fingers occurred in 4 patients in the botulinum group at 4 weeks. One patient's symptoms persisted until week 12, whereas none of the patients receiving placebo had the same complaint. At 4 weeks, 10 patients in the botulinum group and 6 patients in the placebo group experienced weak finger extension on the same side as the injection site.
  
  
  CONCLUSIONS
  The trial was small, and most participants were women. The blinding protocol may have been ineffective because the 4 participants who experienced paresis of the fingers could have correctly assumed that they received an active treatment.
  
  
  CONCLUSIONS
  Botulinum toxin injection may improve pain over a 3-month period in some patients with lateral epicondylitis, but injections may be associated with digit paresis and weakness of finger extension.
authors.affiliation: North District Hospital, The Chinese University of Hong Kong, and Prince of Wales Hospital, Hong Kong, China. jsmwong@hkstar.com
authors.forename: Shiu Man
authors.initials: SM
authors.lastname: Wong
authors.forename: Andrew C F
authors.initials: AC
authors.lastname: Hui
authors.forename: Po-Yee
authors.initials: PY
authors.lastname: Tong
authors.forename: Dawn W F
authors.initials: DW
authors.lastname: Poon
authors.forename: Evelyn
authors.initials: E
authors.lastname: Yu
authors.forename: Lawrence K S
authors.initials: LK
authors.lastname: Wong
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D005385:Fingers / Q000294:innervation; D018737:Hand Strength; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology / Q000517:prevention & control; D010291:Paresis / Q000139:chemically induced; D011446:Prospective Studies; D013716:Tennis Elbow / Q000188:drug therapy* / Q000503:physiopathology; D016896:Treatment Outcome
chemical_list: D019274:Botulinum Toxins, Type A