Effect of the stringency of conditions on caloric test results in healthy subjects. / Efecto de la rigurosidad de las condiciones sobre los resultados de la prueba calórica en sujetos sanos.

The caloric test is widely used to assess vestibular function, but the conditions in which it is performed can vary. Caloric nystagmus obtained in 57 healthy subjects were compared: 24 subjects studied in ideal conditions and 33 subjects in non-ideal conditions. A statistically significant decrease in the slow phase velocity of the 4 irrigations performed on the subjects in non-ideal conditions was observed. This must be considered, especially in subjects with suspected bilateral involvement. Stringent conditions reduce the risk of misdiagnosis with bilateral deficit.

Response Over Time of Vertigo Spells to Intratympanic Dexamethasone Treatment in Meniere's Disease Patients.

OBJECTIVE: To assess the effectiveness and response over time of intratympanic dexamethasone on the symptoms of Meniere's disease. MATERIALS AND METHODS: We performed a matched cohort study of 24 patients with Meniere's disease who were unresponsive to initial treatment and underwent 3 sessions of weekly intratympanic dexamethasone injections using a concentration of 16 mg/mL and 24 matched controls with the same characteristics with regard to vertigo spells. RESULTS: Compared with control subjects, intratympanic dexamethasone injections resulted in a decrease in the frequency of vertigo spells in the first 6-month period. In the dexamethasone-treated group, a ≥60% decrease in vertigo spells was achieved by 70.8% of patients in the first 6 months. Total remission was achieved by 20.8% of patients in the first 8 months, but after this, the effect tapered. A slight improvement in Tinnitus loudness and no changes in hearing levels were found. The stage of Meniere's disease, years from disease onset, and mean number of vertigo spells per month did not have any effects on the percentage of decrease in vertigo spells. CONCLUSION: Intratympanic dexamethasone temporarily reduces the frequency of vertigo spells during the initial months but does not remove the probability of having further spells in the future. This therapy provides a valuable tool to accomplish a rapid decrease in vertigo spells in subjects with Meniere's disease, and it is considered an alternative to chemical or surgical labyrinthectomy.

Increased Velocity Storage in Subjects with Meniere's Disease.

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.