title: Comparative Study on the Roles of the Number of Accelerations and Rotation Angle in the Treatment Maneuvers for Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo.
abstract: OBJECTIVE
  This study aims to investigate the roles of the number of accelerations and rotation angle in the treatment of posterior semicircular canal benign paroxysmal positional vertigo (PC-BPPV).
  
  
  METHODS
  We enrolled 344 patients with unilateral PC-BPPV. Of these, 167 patients in the simple-step maneuver (SSM) group were accelerated twice and rotated 120° per step, whereas 177 patients in the multi-step maneuver (MSM) group were accelerated 4 times and rotated 60° per step. Dix-Hallpike (DH) tests were performed to categorize the treatment outcome as follows: 'symptom free' if the result was negative, 'symptom persistent' if the result remained positive after performing the maneuver 3 times or 'canal conversion' if horizontal nystagmus was evoked.
  
  
  RESULTS
  Of the patients in the SSM and MSM groups, 78.4 and 91.5% became symptom free, respectively, while canal conversion occurred in 13.8 and 5.1%, respectively (p = 0.003, χ(2) test). The success rate after performing the maneuver once was 57.1% in the MSM and 32.3% in the SSM symptom-free patients (p = 0.001, χ(2) test). One month after the treatment, 22.0 and 9.6% of the SSM and MSM patients had symptom relapse, respectively (p = 0.007, χ(2) test).
  
  
  CONCLUSIONS
  More accelerations and a smaller rotation angle improved the effectiveness and efficiency of the repositioning maneuvers and reduced canal conversion.
authors.affiliation: Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai Clinical Medical Center of Hearing Medicine, and Key Laboratory of Hearing Science, Ministry of Health, Shanghai, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Tian
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Sheng
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Xu
authors.initials: X
authors.lastname: Luo
authors.forename: Jing
authors.initials: J
authors.lastname: Yu
authors.forename: Xian-Hao
authors.initials: XH
authors.lastname: Jia
authors.forename: Xiang
authors.initials: X
authors.lastname: Cheng
authors.forename: Zhao
authors.initials: Z
authors.lastname: Han
authors.forename: Fang-Lu
authors.initials: FL
authors.lastname: Chi
mesh_terms: D000054:Acceleration; D065635:Benign Paroxysmal Positional Vertigo / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D004864:Equipment and Supplies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D026741:Physical Therapy Modalities; D011446:Prospective Studies; D012399:Rotation; D012665:Semicircular Canals / Q000503:physiopathology; D016037:Single-Blind Method; D016896:Treatment Outcome