Search

BACKGROUND: Hyperventilation-induced nystagmus test (HINT) is capable of generating a response in 77.2% of cases of acute unilateral vestibulopathy (AUVP); both nystagmus toward the affected side (excitatory pattern) and toward the healthy side (inhibitory pattern) have been described. The aim of the study is to investigate the clinical and prognostic role of the test by evaluating its correlation with vestibulo-ocular reflex (VOR) gain. METHODS: We evaluated 33 AUVP patients by performing the HINT and video head impulse test (V-HIT) during the acute phase and then at 15 and 90 days after the onset of the symptoms. The correlation between the VOR gain of the affected side and test responses was evaluated first, phase by phase, and then considering the pattern shown during the first assessments. RESULTS: Patients with a negative HINT had a higher mean VOR gain than patients with a positive test at both 15 and 90 days. Patients who showed an inhibitory pattern at the first assessment had a continuous improvement in V-HIT performance, while patients with an initial excitatory response had a transient decrease in gain at the subsequent evaluation (P=.001). No difference between these 2 groups emerged at 90 days (P=.09). CONCLUSION: The finding of a negative HINT during the follow-up correlates with good V-HIT performance and could be an indicator of good recovery. The inhibitory pattern is associated with a subsequent improvement; and it would be indicative of compensation. but, despite this, the prognostic value of the test is limited [ABSTRACT FROM AUTHOR]

We present an unusual case of a patient with a positive Tullio phenomenon, brief Valsalva-induced transient horizontal nystagmus, reduced left caloric response, and bilateral vestibulo-ocular reflex loss. This study discusses the pathophysiology and differential diagnosis concerning the suspected pathology for the phenomenon of utricular hydrops or vestibular atelectasis and presents a literature review. [ABSTRACT FROM AUTHOR]

We present an unusual case of a patient with a positive Tullio phenomenon, brief Valsalva-induced transient horizontal nystagmus, reduced left caloric response, and bilateral vestibulo-ocular reflex loss. This study discusses the pathophysiology and differential diagnosis concerning the suspected pathology for the phenomenon of utricular hydrops or vestibular atelectasis and presents a literature review. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of this study is to compare nystagmus characteristics after caloric irrigation in patients with lateral canal (LC) and posterior canal (PC) benign paroxysmal positional vertigo (BPPV) and to analyze the role of symptom duration. MATERIALS and METHODS: A prospective study was conducted in 65 patients with BPPV (20 LC and 45 PC) who were subjected to caloric testing. Average slow-phase velocity and nystagmus duration were analyzed. RESULTS: Caloric hypo-excitability was 20.4%. It was more evident in patients with apogeotropic-type LC-BPPV. The comparison of average slowphase velocity of the nystagmus and nystagmus duration between selected types of BPPV for pathologic, non-pathologic, and the control ears after warm and cold stimulation was not statistically significant (p>0.05). No correlation was found between caloric results and symptom duration (p>0.05). CONCLUSION: Some patients presented caloric hypo-excitability. Reliability of caloric testing to differentiate the ear with normal and abnormal vestibular function in different types of BPPV was low. No difference was found in the analysis of the impact of symptom duration. Caloric testing is not an ideal tool to study BPPV [ABSTRACT FROM AUTHOR]

OBJECTIVE: Velocity storage mechanism is a multisensory rotation estimator; it compensates for errors in the information provided by the peripheral vestibular organs by means of an adjustment in the duration of the vestibular signal. The aim of this study was to determine the activity of the velocity storage mechanism in the presence of a labyrinthine disorder, using galvanic vestibular stimulation to cause direct activation of the vestibular afferent neurons. MATERIALS and METHODS: Forty-one subjects with definite Meniere's disease (MD) and 36 healthy volunteers were evaluated using a 20-s galvanic vestibular stimulation. RESULTS: We found a post-stimulus nystagmus overshoot exclusively in subjects with MD (47% in subjects with unilateral disease and 82% in subjects with bilateral disease), but no overshoot in healthy subjects. CONCLUSION: Because post-stimulus nystagmus overshoot is caused by the velocity storage mechanism, this finding suggests an increase in the velocity storage in subjects with a labyrinthine disease. [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]