title: Saccadic Velocity in the New Suppression Head Impulse Test: A New Indicator of Horizontal Vestibular Canal Paresis and of Vestibular Compensation.
abstract: OBJECTIVE
  To determine whether saccadic velocity in the suppression head impulse paradigm (SHIMP) test is a reliable indicator of vestibular loss at the acute and at the chronic stage in patients suffering from different vestibular pathologies.
  
  
  METHODS
  Thirty-five normal subjects and 57 patients suffering from different vestibular pathologies associated with unilateral vestibular loss (UVL) or bilateral vestibular loss (BVL) were tested in the SHIMPs paradigm. SHIMPs were performed by turning the head 10 times at high velocities to the left or right side, respectively. The patients were instructed to fixate on a red spot generated by a head-fixed laser projected on the wall. In this SHIMPs paradigm, healthy subjects made a large anti-compensatory saccade at the end of the head turn (a SHIMP saccade). The peak saccadic velocity, the percentage of the trials completed with saccades in 10 trials, and the latency of the saccades were quantified in each group. A video-head impulse test (v-HIT) was systematically performed in all of our subjects as well as a caloric test. The dizziness handicap inventory questionnaire was also given to chronic UVL and BVL patients.
  
  
  RESULTS
  At the acute stage after a complete UVL, patients had zero or a few anti-compensatory saccades for low velocity head turns toward the lesioned side. These saccades had lower velocity than the anti-compensatory saccades recorded during head rotation toward the intact side and/or compared with the saccades measured in control subjects. At the chronic stage, some of the patients recovered the ability to perform SHIMP saccades at each head turn toward the lesioned side, but very often these saccades were of significantly lower velocity. In BVL patients, no anti-compensatory saccades, or only significantly smaller ones, could be detected for head turns to both sides.
  
  
  CONCLUSIONS
  SHIMP is a specific and sensitive test to detect a complete horizontal canal loss at the acute stage. In addition, it reflects the ability of patients with moderate horizontal vestibulo-ocular reflex gain decrease to generate anti-compensatory saccades in the chronic stage. In association with v-HIT, it allows determination of the residual vestibular function and to detect anti-compensatory saccades.
authors.affiliation: Cognition and Action Group, CNRS UMR8257, Centre Universitaire des Saints-Peres, Universite Paris Descartes , Paris , France.
authors.forename: Qiwen
authors.initials: Q
authors.lastname: Shen
authors.affiliation: Cognition and Action Group, CNRS UMR8257, Centre Universitaire des Saints-Peres, Universite Paris Descartes , Paris , France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Magnani
authors.affiliation: ENT Department, Salpetriere Hospital , Paris , France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Sterkers
authors.affiliation: ENT Department, Salpetriere Hospital , Paris , France.
authors.forename: Georges
authors.initials: G
authors.lastname: Lamas
authors.affiliation: Cognition and Action Group, CNRS UMR8257, Centre Universitaire des Saints-Peres, Universite Paris Descartes , Paris , France.
authors.forename: Pierre-Paul
authors.initials: PP
authors.lastname: Vidal
authors.affiliation: Cognition and Action Group, CNRS UMR8257, Centre Universitaire des Saints-Peres, Universite Paris Descartes , Paris , France.
authors.forename: Julien
authors.initials: J
authors.lastname: Sadoun
authors.affiliation: Vestibular Research Laboratory, School of Psychology, University of Sydney , Sydney, NSW , Australia.
authors.forename: Ian S
authors.initials: IS
authors.lastname: Curthoys
authors.affiliation: Cognition and Action Group, CNRS UMR8257, Centre Universitaire des Saints-Peres, Universite Paris Descartes, Paris, France; ENT Department, Salpetriere Hospital, Paris, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: de Waele
keywords: IT gentamicin; Meniere’s disease; bilateral areflexia; horizontal vestibule–ocular reflex; saccade substitution; vestibular loss; vestibular schwannoma; video-head impulses