A Device for the Functional Evaluation of the VOR in Clinical Settings

Abstract

We developed the head impulse testing device (HITD) based on an inertial sensing system allowing to investigate the functional performance of the rotational vestibulo-ocular reflex (VOR) by testing its gaze stabilization ability, independently from the subject’s visual acuity, in response to head impulses at different head angular accelerations ranging from 2000 to 7000 deg/s2. HITD was initially tested on 22 normal subjects, and a method to compare the results from a single subject (patient) with those from controls was set up. As a pilot study, we tested the HITD in 39 dizzy patients suffering, non-acutely, from different kinds of vestibular disorders. The results obtained with the HITD were comparable with those from the clinical head impulse test (HIT), but an higher number of abnormalities was detectable by HITD in the central vestibular disorders group. The HITD appears to be a promising tool for detecting abnormal VOR performance while providing information on the functional performance of the rotational VOR, and can provide a valuable assistance to the clinical evaluation of patients with vestibular disorders.

Validation of the Italian Version of the Dizziness Handicap Inventory, the Situational Vertigo Questionnaire, and the Activity-Specific Balance Confidence Scale for Peripheral and Central Vestibular Symptoms

“…For all patients, we collected demographic and clinical data and performed a standard neuro-otological examination including checking for the presence and the features of nystagmus (direction, amplitude, conjugacy and waveform, effect of preventing visual fixation), positional testing, hyperventilation, head shaking test, head impulse test, and Valsalva maneuver. Instrumental evaluation included caloric and rotational testing and instrumental head impulse testing ( 35 – 38 ). Clinical variables relevant for subsequent test of their association with the questionnaires’ scores were: disease duration, migraine diagnosis; visual vertigo; vestibular deficit (defined by clinical and instrumental evaluation); diagnosis (defined on the basis of anamnestic, clinical, and instrumental evaluation).…”

Normal Gain of VOR with Refixation Saccades in Patients with Unilateral Vestibulopathy

“…In a clinical setting, new video-based equipment has recently been introduced, which enables registration of the eye in response to sudden head impulses [7][8][9] . This is called the video head-impulse test (vHIT).…”

Head Impulse Test

“…By making head rotations in the directions of semicircular canal pairs, it can detect a deficit in the canal being tested. 15 As per Ewald's laws, a deficit in the horizontal canal can be unveiled when rotation in the direction of the concerned canal detects a corrective saccade (vide supra). For the vertical canals, the deficiencies are unveiled when the canal is stimulated in the opposite direction of their ampulla.…”