Journal of Vestibular Research

The video head impulse test (vHIT) is a common assessment of semicircular canal function during high-speed impulses. Reliability of the vHIT for assessing vertical semicircular canals is uncertain. Vertical head impulses require a complex head movement, making it difficult to isolate a single semicircular canal and interpret resulting eye rotations.

The purpose of this study was to provide descriptive head kinematics and vestibular stimuli during vertical plane impulses to ultimately improve impulse delivery and interpretation of vHIT results for vertical semicircular canals.

Six participants received right anterior (RA) and left posterior (LP) semicircular canal impulses. Linear displacements, rotational displacements, and rotational velocities of the head were measured. Peak velocities in semicircular canal planes and peak-to-peak gravitoinertial accelerations at the otolith organs were derived from head kinematics.

The largest rotational velocities occurred in the target semicircular canal plane, with non-negligible velocities occurring in non-target planes. Larger vertical displacements and accelerations occurred on the right side of the head compared to the left for RA and LP impulses.

These results provide a foundation for designing protocols to optimize stimulation applied to a singular vertical semicircular canal and for interpreting results from the vHIT for vertical semicircular canals.

Patients with vestibular loss have reduced wayfinding ability, but the association between vestibular loss and impaired steering spatial navigation is unclear.

To evaluate whether vestibular loss is associated with reduced steering navigation performance in a virtual reality (VR) environment containing obstacles.

17 ambulatory adults with vestibular loss were age/sex-matched to healthy controls. Participants traversed a VR hallway with obstacles, and their navigation performance was compared using metrics such as collisions, time, total distance travelled, and speed in single and multivariate analysis.

In univariate analysis there was no significant difference in collisions between vestibular patients and controls (1.84 vs. 2.24, p = 0.974). However, vestibular patients took more time, longer routes, and had lower speeds to complete the task (56.9 vs. 43.9 seconds, p < 0.001; 23.1 vs. 22.0 meters, p = 0.0312; 0.417 vs. 0.544 m/s, p < 0.001). These results were confirmed in multivariate analysis.

This study found that patients with vestibular loss displayed slower gait speeds and traveled longer distances, though did not make more collisions, during a VR steering navigation task. Beyond the known influence of vestibular function on gait speed, vestibular loss may also contribute to less efficient steering navigation through an obstacle-laden environment, through neural mechanisms that remain to be elucidated.

Impairment of visual fixation suppression (VS) in progressive supranuclear palsy (PSP) is not well documented.

To evaluate the usefulness of impaired VS of caloric nystagmus as an index for differential diagnosis between PSP and Parkinson’s disease (PD), which is often difficult, especially in the early stage.

Subjects comprised 26 PSP patients and 26 PD patients clinically diagnosed at Tokyo Metropolitan Neurological Hospital. We retrospectively investigated VS of caloric nystagmus, horizontal pursuit, saccades, and horizontal optokinetic nystagmus recorded on direct-current-electronystagmography, and neuroradiological findings.

The median of the average VS% was 0% and 50.0% in PSP and PD patients, respectively. In PSP, VS was impaired even in the early stage of disease. We found a significant correlation between VS and velocity of saccades or maximum slow phase velocity of optokinetic nystagmus only in PSP patients. PSP patients with atrophy of the subthalamic nucleus or with decreased blood flow in the frontal lobe showed significantly more severe impairment of VS.

VS may be a useful biomarker to differentiate patients with PSP from those with PD. Cerebellar networks that connect with the cerebral cortex and basal ganglia may contribute to impaired VS of caloric nystagmus in PSP.

Cochlear implantation (CI) is associated with changes in the histopathology of the inner ear and impairment of vestibular function.

The objectives of our study were to evaluate patients for clinical manifestations of space perception and balance changes before surgery, compare them with asymptomatic subjects (controls), and report changes in posturography and subjective visual vertical (SVV) during the acute post-surgery period in patients.

Examination was performed using static posturography and the SVV measurement. We examined 46 control subjects and 39 CI patients. Patients were examined pre-surgery (Pre), 2nd day (D2) and then 14th day (D14) after implantation.

Baseline SVV was not different between patients and control group. There was a statistically significant difference (p < 0.001) in SVV between subgroups of right- and left-implanted patients at D2 (–1.36±3.02° and 2.71±2.36°, right and left side implanted respectively) but not Pre (0.76±1.07° and 0.31±1.82°) or D14 (0.72±1.83° and 1.29±1.60°). Baseline posturography parameters between patients and control group were statistically significantly different during stance on foam with eyes closed (p < 0.05). There was no statistically significant difference in posturography among Pre, D2 and D14.

CI candidates have impaired postural control before surgery. CI surgery influences perception of subjective visual vertical in acute post-surgery period with SVV deviation contralateral to side of cochlear implantation, but not after two weeks.

To comprehensively evaluate the dynamic change of vestibular function during long-term follow-up of vestibular neuritis, as well as the co-relationship with the outcomes of vestibular neuritis (VN), which provides the recommendations for vestibular function tests during the course of VN.

A prospective cohort study was conducted on 16 patients with acute VN. Caloric test, vHIT, rotatory chair tests, VEMP, dizziness handicap inventory (DHI) score, and dynamic dizzy scales (VAS-DD) was first performed within 7 days of neuritis onset, which were further re-evaluated during the 6–12 months of follow-up. The dynamic changes on multiple objective vestibular examinations were analyzed during the acute and recovery stage of VN. We further evaluated the co-relationship between the vestibular dysfunction scales and the prognosis of VN.

In more than 6 months of follow-up, 44% of the ultralow frequency, 94% of the low-to-mid frequency, and 44% of the high-frequency function of the horizontal semicircular canal returned to normal (p < 0.05). The change degree in symmetry of the rotatory chair test was correlated with the gain of the horizontal semicircular canal on the vHIT and the unilateral weakness (UW) value on the caloric test (p < 0.05). The change in DHI score was correlated with the phase; change in VAS-DD level correlated with the symmetry and TC of the rotatory chair test at VN recovery stage (p < 0.05). There was no significant correlation between the change in DHI score or change in VAS-DD and the degree of vestibular function recovery (p > 0.05).

In general, vestibular function improved during the course of VN. The rotatory chair test can be used to evaluate the overall function of the vestibular system and the compensatory state in patients with VN.

The reproducibility of the effective intensity of noisy galvanic vestibular stimulation (nGVS) to improve postural stability is not well known.

We aimed to investigate inter-day and intra-day variations in effective intensity in patients with bilateral vestibulopathy (BVP).

Thirteen BVP patients were measured for center-of-pressure movements in the standing posture at five time points: morning of the first test day, morning and evening of the second test day, and morning and evening of the third test day. The mean velocity, the envelopment area, and the root mean square were measured in the eyes-closed condition for 30 s during nGVS application ranging from 0 to 1000μA. The effective intensity was defined as the intensity at which all the three parameters measured during the stimulation were simultaneously smaller than the values at baseline (0μA).

Seven of the 13 patients had a common effective intensity throughout the three test days. Six patients on the second test day and five patients on the third test day had no common effective intensity between morning and evening.

The effective intensity of nGVS changes depending on the time during the day as well as between the days.