The Role of Functional Head Impulse Test With and Without Optokinetic Stimuli in Vestibular Migraine and Acute Unilateral Vestibulopathy: Discovering a Visual Dependence?

Abstract Visually induced vertigo (i.e., vertigo provoked by moving visual scenes) could be considered as a noticeable feature of Vestibular Migraine (VM) and could be present in patients suffering from Acute Unilateral Vestibulophaty (AUV). The hypersensitivity to moving or conflicting visual stimulations is named Visual Dependence. The visuo-vestibular interactions were analyzed using functional Head Impulse Test (fHIT) with and without optokinetic stimulation (o-fHIT) in 25 patients with VM and 20 subjects affected by AUV. We calculated the percentage of correct answer (%CA) without and with the addition of confounding screen (CS). In VM groups the %CA at fHIT was 92,07% without CS and 73,66% with CS. A significant difference has been found between %CA on the deficit side and the normal side in AUV, both without CS and with CS). The results of fHIT in term of %CA with and without CS could be very useful to identify the presence of visual dependence especially in patients suffering from VM. The difference of %CA with and without CS could provide an instrumental support to correctly identify patients with VM. We propose the use of fHIT in clinical practice whenever there is a need to highlight a condition of visual dependence.