title: Vestibular neuritis: Involvement and long-term recovery of individual semicircular canals.
abstract: OBJECTIVE
  In this retrospective study, the aim of the authors was to examine the frequency of involvement of the individual semicircular canals (SCCs) in vestibular neuritis (VN) and to assess the degree of long-term recovery. A secondary aim was to retrospectively determine the usefulness of a three-step bedside oculomotor test (the HINTS-test) for the differential diagnosis of peripheral VN.
  
  
  METHODS
  44 cases were evaluated during the acute phase and approximately two months later. The gain of the vestibuloocular reflex was determined using video-head-impulse test, carried out using Otometrics ICS Impulse Otosuite Vestibular V 1.2.
  
  
  RESULTS
  In 19 cases (43%), a typical, so called "superior" VN could be diagnosed; in 17 cases (38%), all three SCCs were involved; in 4 cases, an isolated inferior canal involvement was seen; and in another 4 cases, a slight, isolated horizontal canal involvement was registered. Slight, isolated horizontal canal vestibular neuritis causing acute vestibular syndrome has not yet been reported in the literature. A three-step bedside oculomotor examination, the HINTS-test (head-impulse test, examination of gaze evoked nystagmus, and test of skew-deviation), suggested peripheral involvement in all cases with superior pattern VN and in cases when all three SCC were involved. It indicated 'stroke' in cases with inferior pattern and in the cases with isolated involvement of the horizontal canal. At follow-up, the horizontal canal function normalized in 55%, the anterior canal in 38%, and the inferior in 38%. When all cases were pooled, 14 patients recovered completely. In cases with severe initial decrease of gain in the horizontal canal (initial value less than 0.5), the canals had a 50 per cent chance to recover significantly.
  
  
  CONCLUSIONS
  In vestibular neuritis, in cases with severe decrease of gain in the horizontal canal (initial value less than 0.5), the canal has a 50 per cent chance to recover significantly. The vertical canals have worse prognosis, and especially the inferior canals seldom improve. Slight, isolated horizontal canal vestibular neuritis may cause acute vestibular syndrome, most probably by the same mechanism as full-blown vestibular neuritis. In these cases, the three-step bedside oculomotor test may indicate cerebellar stroke (may be false positive).
authors.affiliation: Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria. Electronic address: bukibela@hotmail.com.
authors.forename: Bela
authors.initials: B
authors.lastname: Büki
authors.affiliation: Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria.
authors.forename: Manuela
authors.initials: M
authors.lastname: Hanschek
authors.affiliation: Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria.
authors.forename: Heinz
authors.initials: H
authors.lastname: Jünger
mesh_terms: D000328:Adult; D000368:Aged; D005133:Eye Movements; D005260:Female; D005500:Follow-Up Studies; D064087:Head Impulse Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000503:physiopathology; D020127:Recovery of Function; D012027:Reflex, Vestibulo-Ocular; D012189:Retrospective Studies; D012665:Semicircular Canals / Q000503:physiopathology*; D020338:Vestibular Neuronitis / Q000503:physiopathology* / Q000628:therapy
keywords: HINTS; Head-impulse test; Vestibular neuritis