Functional Head Impulse Test With and Without Optokinetic Stimulation in Subjects With Persistent Postural Perceptual Dizziness (PPPD): Preliminary Report.

Objective: Persistent postural perceptual dizziness (PPPD) is a clinical condition characterized by unsteadiness present on most days for a period of at least 3 months. The aim of our work was to assess vestibular function, the role of anxiety, and possible interactions between visual and vestibular systems in patients with PPPD.
Study Design: Cross-sectional prospective study.
Setting: Tertiary referral center.
Patients: Twenty-five PPPD patients.
Interventions: Clinical history was collected before examination; vestibular function was assessed through bedside examination, video and functional head impulse test (video-HIT, f-HIT). The latter test was based on having the patient identify an optotype displayed on a computer screen during passive head rotations. The test was repeated while optokinetic stimulation (OKS) was given on the screen. Results were compared with those of 25 controls. State and trait anxiety levels were measured with the State-Trait Anxiety Inventory (STAI) questionnaire. Anxiety before and after vestibular examination was assessed using a VAS scale.
Main Outcome Measure: Results of video and functional HIT with and without OKS.
Results: Video-HIT and f-HIT showed normal values in all subjects. f-HIT with OKS provoked more reading errors in patients than in controls. The interaction of group per time detected different decreasing trends between the two groups (p = 0.0002).Patients presented a reduction in anxiety levels after examination. Nine patients fulfilled diagnostic criteria for vestibular migraine, eight of whom presented nystagmus either to positional tests or vibration test. Only anxiety levels before testing were predictive of worsening of f-HIT with optokinetic stimulation (p = 0.0007).
Conclusions: Our data support the hypothesis that increased anxiety may play a role in visuo-vestibular interactions; moreover, they are not inconsistent with the hypothesis that OKS might provoke a "threatening effect," leading to gaze bias during examination.