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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]

Objective The caloric test and the video head-impulse test are diagnostic tools to examine dizzy patients through assessing the function of the semicircular canals. There are major differences between the two tests as regards stimulus characteristics, methodology, and function examined. The aim of this study is to evaluate the results of vHIT in children and adolescents with normal caloric test. Materials and methods This work was performed on 63 patients, but 14 were excluded because of technical problems in the caloric test. So, this is a prospective work in 49 patients (27 females and 22 males) with different types of vestibular disease seen because of vertigo in which both procedures were performed the same day. The caloric test was performed with air at two different temperatures in which both ears were irrigated alternately. Then, the video head-impulse test was carried out. Main outcome measures were the gain of vestibulo-ocular reflex, gain asymmetry, and refixation saccades in the vHIT. Results in all studied cases, caloric test was normal. The mean age of patients was 16 years. By vHIT, in 8 patients (16%) no abnormality was detected, while abnormal findings were found in 41 patients. Single canal affection was seen in 29 patients whereas 12 patients had combined canal affection. The right side was affected in 27 and left side in 22 patients. In single canal affection, isolated horizontal canals were affected in 4, anterior canals in 5 and posterior canals in 20 patients. While in combined canal affection, the affection is seen in the same ear. Moreover the most common pattern seen is affection of left anterior and left posterior canals. Conclusion The caloric and vHIT is very important tests in diagnosis of dizzy patients. The information from both methods is redundant in some cases but complementary in most. vHIT is a “child friendly,” relatively easy-to-use, and simple tool to evaluate each of the 6 semicircular canals. [ABSTRACT FROM AUTHOR]

The video head impulse test (vHIT) assesses the vestibulo-ocular reflex (VOR) during a rapid high-velocity low amplitude (10°–20°) head rotation. Patients with peripheral vestibulopathy have a reduced VOR gain with corrective catch-up saccades during the head turn. There are several pitfalls, mainly technical, which may interfere with interpretation of vHIT data. In addition, intrusive eye movement disorders such as spontaneous nystagmus that affect normal eye position and tracking can affect the vHIT results. To date there has been little study of neurological saccadic eye movements that may interfere with the interpretation of vHIT data. Here, in ten patients with a range of central neurological disorders, we describe oculomotor abnormalities on vHIT in the presence of normal range VOR gain values, recorded at a tertiary vestibular neurology service. • Certain apparent catch-up saccades visible on the vHIT data may be due to the gaze-evoked nystagmus, induced by the head turn and transient eccentric positioning of the eyes. • Saccadic oscillations may affect the vHIT by appearing immediately after the head impulse and may be indistinguishable from an overt saccade if seen without clinical correlation. • Our cases highlight that oculomotor abnormalities can interfere with quantitative recording of the head impulse VOR responses and may impact the clinical diagnosis. [ABSTRACT FROM AUTHOR]