title: Saccadic entropy of head impulses in acute unilateral vestibular loss.
abstract: OBJECTIVE
  To evaluate the complexity of vestibular-ocular reflex (VOR) in patients with acute unilateral vestibular loss (AUVL) via entropy analysis of head impulses.
  
  
  METHODS
  Horizontal head impulse test (HIT) with high-velocity alternating directions was used to evaluate 12 participants with AUVL and 16 healthy volunteers. Wireless electro-oculography and electronic gyrometry were used to acquire eye positional signals and head velocity signals. The eye velocity signals were then obtained through differentiation, band-pass filtering. The approximate entropy of eye velocity to head velocity (RApEn) was used to evaluate chaos property. VOR gain, gain asymmetry ratio, and RApEnasymmetry ratio were also used to compare the groups.
  
  
  RESULTS
  For the lesion-side HIT of the patient group, the mean VOR gain was significantly lower and the mean RApEnwas significantly greater compared with both nonlesion-side HIT and healthy controls (p < 0.01, one-way analysis of variance). Both the RApEnasymmetry ratio and gain asymmetry ratio of the AUVL group were significantly greater compared with those of the control group (p < 0.05, independent sample t test).
  
  
  CONCLUSIONS
  Entropy and gain analysis of HIT using wireless electro-oculography system could be used to detect the VOR dysfunctions of AUVL and may become effective methods for evaluating vestibular disorders.
authors.affiliation: Department of Otolaryngology, Mackay Memorial Hospital, Taipei, Taiwan; Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Audiology and Speech Language Pathology, Mackay Memorial Medical College, Taiwan.
authors.forename: Li-Chun
authors.initials: LC
authors.lastname: Hsieh
authors.affiliation: Department of Otolaryngology, Mackay Memorial Hospital, Taipei, Taiwan; Department of Audiology and Speech Language Pathology, Mackay Memorial Medical College, Taiwan.
authors.forename: Hung-Ching
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Otolaryngology, Taipei City Hospital, Renai Branch, Taipei, Taiwan. Electronic address: guosheli@gmail.com.
authors.forename: Guo-She
authors.initials: GS
authors.lastname: Lee
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D019277:Entropy; D005260:Female; D006257:Head; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D012372:ROC Curve; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012438:Saccades / Q000502:physiology*; D014717:Vertigo / Q000209:etiology; D014722:Vestibule, Labyrinth / Q000503:physiopathology*
keywords: acute vestibular loss; chaotic analysis; gain asymmetry; head impulse tests; saccadic entropy