Search

Objective: Some studies have suggested that the human immunodeficiency virus causes dizziness and other balance problems; however, the exact effects on the vestibular system in acute and chronic phases of the disease are not clear. In this study, we aimed to evaluate the effect of the human immunodeficiency virus on semicircular canals using a video head impulse test. Materials and Methods: Seventy-two cases were included in the study. Twenty-six of the cases had positive human immunodeficiency virus RNA (group A) and 22 had negative human immunodeficiency virus RNA with positive anti-human immunodeficiency virus (group B) laboratory results. Twenty-four of the cases were healthy individuals (group C). The vestibular system was evaluated with a video head impulse test in all cases. Results: In the evaluation of overt/covert saccades, a statistically significant difference was detected for the left posterior semicircular canal between group B and the other 2 groups. However, this was considered an incidental finding and not a clinically significant result. There was no other significant difference in the catchup saccades for other canals. In addition, there was no statistically significant difference between the groups for the vestibulo-ocular reflex gain. Conclusion: Although the human immunodeficiency virus has been reported to be vestibulotoxic in previous studies, we found that the video head impulse test findings were not affected in our patient groups. Because the video head impulse test is considered a high-frequency test of vestibulo-ocular reflex, it is possible that vestibular effects of the human immunodeficiency virus can be confined to low frequencies. It is also possible that HIV affects the central structures while sparing the peripheral vestibular pathways. [ABSTRACT FROM AUTHOR]

BACKGROUND: The crucial role of early vestibular rehabilitation (VR) to recover a dynamic semicircular canal function was recently highlighted in patients with unilateral vestibular hypofunction (UVH). However, wide inter-individual differences were observed, suggesting that parameters other than early rehabilitation are involved. OBJECTIVE: The aim of the study was to determine to what extent the degree of vestibular loss assessed by the angular vestibulo-ocular reflex (aVOR) gain could be an additional parameter interfering with rehabilitation in the recovery process. And to examine whether different VR protocols have the same effectiveness with regard to the aVOR recovery. METHODS: The aVOR gain and the percentage of compensatory saccades were recorded in 81 UVH patients with the passive head impulse test before and after early VR (first two weeks after vertigo onset: N = 43) or late VR (third to sixth week after onset: N = 38) performed twice a week for four weeks. VR was performed either with the unidirectional rotation paradigm or gaze stability exercises. Supplementary outcomes were the dizziness handicap inventory (DHI) score, and the static and dynamic subjective visual vertical. RESULTS: The cluster analysis differentiated two distinct populations of UVH patients with pre-rehab aVOR gain values on the hypofunction side below 0.20 (N = 42) or above 0.20 (N = 39). The mean gain values were respectively 0.07±0.05 and 0.34±0.12 for the lateral canal (p < 0.0001), 0.09±0.06 and 0.44±0.19 for the anterior canal (p < 0.0001). Patients with aVOR gains above 0.20 and early rehab fully recovered dynamic horizontal canal function (0.84±0.14) and showed very few compensatory saccades (18.7% ±20.1%) while those with gains below 0.20 and late rehab did not improve their aVOR gain value (0.16±0.09) and showed compensatory saccades only (82.9% ±23.7%). Similar results were found for the anterior canal function. Recovery of the dynamic function of the lateral canal was found with both VR protocols while it was observed with the gaze stability exercises only for the anterior canal. All the patients reduced their DHI score, normalized their static SVV, and exhibited uncompensated dynamic SVV. CONCLUSIONS: Early rehab is a necessary but not sufficient condition to fully recover dynamic canal function. The degree of vestibular loss plays a crucial role too, and to be effective rehabilitation protocols must be carried out in the plane of the semicircular canals. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The caloric test and the video head-impulse test are diagnostic tools that examine the function of the horizontal semicircular canal. There are major differences between the two tests. These are stimulus characteristics, methodology, and function examined. MATERIALS and METHODS: This is a prospective work in 123 patients with different types of vestibular disease seen because of dizziness in which both procedures were performed the same day. First, the spontaneous nystagmus and head-shake nystagmus were measured. The video head-impulse test was carried out, and finally, the caloric test was performed with water at two different temperatures. Both ears were irrigated alternately. Main outcome measures were the canal paresis in the caloric test and gain of vestibulo-ocular reflex, gain asymmetry, and refixation saccades in the vHIT. RESULTS: The caloric test and the vHIT results were fully coincident in 60 patients (48.7%), and the results for both were normal in 36 patients. Discrepancies were found in 3 patients regarding the deficient side, and in 14 patients, an added contralateral (according to the caloric test) abnormal result was obtained. In 46 patients, one of the tests was normal while the other was not, but both were in accordance with the diseased side. The correlation coefficient for canal paresis and gain asymmetry was 0.67, and the agreement was low: κ=0.252. CONCLUSION: The assessment of horizontal semicircular canal function with the vHIT needs to take into consideration not only the gain in VOR but also the existence of refixation saccades. The information from both methods is redundant in some cases but complementary in most, and the existence of discrepancies is very low. [ABSTRACT FROM AUTHOR]