Normative data for static balance testing in healthy individuals using open source computerized posturography.

PURPOSE: Computerized posturography is the gold standard for balance assessment. Because of the great cost and dimensions of commercial equipments, low-cost and portable devices have been developed and validated, such as RombergLab, a software in open source term which works connected with a low-cost force platform. The objective of this study was to obtain normative posturography data using this software. METHODS: A multicentric prospective and descriptive study, with 350 healthy participants, was designed. Static postural stability (measured using the modified clinical test of sensory interaction on balance) was evaluated using the software connected to the force platform. Using the confidence ellipse area (CEA) in each condition, global equilibrium score (GES) was calculated and adjusted for significant variable factors using cluster analysis. RESULTS: Mean (SD) GES was 0.72 (0.22). Age (p < 0.01), height (p < 0.01) and recruitment center (p < 0.05) were found as influence factors for GES. Cluster analysis obtained 16 groups stratified by age and height. GES decreases with age and height (p < 0.005). No significant interaction of age nor height was found with GES in these clusters (p > 0.05). After correction for height and age, GES was no longer influenced by the recruitment center (p > 0.05). CONCLUSIONS: With the introduction of the global equilibrium score values of the present study into the software, we consider RombergLab v1.3 a reference posturography tool for healthy individuals. Further studies are needed for validating it as a suitable instrumented test for screening between healthy and pathologic subjects and its reliability over time for the follow-up of patients.

Seasonality and solar radiation variation level in benign paroxysmal positional vertigo.

BACKGROUND: Several studies have shown that the incidence of benign paroxysmal positional vertigo (BPPV) presents seasonal variations and there is evidence that the variation in time is dependent on the patient's amount of vitamin D. OBJECTIVES: This is a retrospective study to verify if there is a correlation between the incidence of BPPV and the level of solar radiation, essential for the synthesis of vitamin D in the skin. MATERIAL AND METHODS: This study comprised 214 patients with BPPV seen from 2012 to 2017, in a city Latitude: -30.0277, Longitude: -51.2287 30° 1' 40″ South, 51° 13' 43″ West. The amounts of monthly solar radiation were analyzed in relation to the dates of their first consultations. Statistical tests were employed to verify the existence of a correlation between solar radiation and the incidence of the disease. RESULTS: The statistical analysis revealed a significant difference between the incidence of BPPV and the amount of radiation during the month of the diagnosis of the disease. There was also a significant statistical correlation with the climatic variation. CONCLUSION: More patients with benign paroxysmal positional vertigo (BPPV) are seen in consultation in the months with low solar radiation and in the autumn and winter seasons, in this geographic city.

Distortion product otoacoustic emissions in an animal model of induced hyperinsulinemia.

The existence of a relationship between abnormal insulin levels and the occurrence of labyrinth disorders has been demonstrated in several works. Among many metabolic alterations, such studies indicate that hyperinsulinemia is one of the most frequent causes of cochlear and vestibular syndromes. In this study, we monitored distortion product evoked otoacoustic emission thresholds during induced acute hyperinsulinemia in sheep so as to identify the occurrence of electrophysiological changes in cochlear outer hair cells. In the study group, seven sheep received a bolus of 0.1 U/kg of regular human insulin. In the control group, seven sheep received saline solution. We measured insulin and glucose levels simultaneously with the recording of distortion product otoacoustic emissions at 10-minute intervals over 90 minutes. We successfully induced hypoglycemia and hyperinsulinemia. We detected no changes in distortion product thresholds in the control group during the 90 minutes of the experiment. In the study group, we recorded a reduction in distortion product thresholds in relation to the control group at frequencies above 1,500 Hz and after 60 minutes (p < .001). We observed significant electrophysiological changes in cochlear outer hair cells reflected in the variation of distortion product thresholds at high frequencies after 60 minutes.

Behavior of the Posterior Semicircular Canal After Dix-Hallpike Maneuver.

The objective of the present study is to analyze the quantitative vestibulo-ocular responses in a group of patients with benign paroxysmal positional vertigo (BPPV) canalolithiasis and compare these data with the data of the tridimensional biomechanical model. This study was conducted on 70 patients that presented idiopathic posterior semicircular canal canalolithiasis. The diagnosis was obtained by Dix-Hallpike maneuvers recorded by videonystagmograph. The present study demonstrates that there is a significant correlation between the intensity of the nystagmus and its latency in cases of BPPV-idiopathic posterior semicircular canal canalolithiasis type. These findings are in agreement with those obtained in a tridimensional biomechanical model and are not related to the patients' age.

Assessment of the vestibuloocular reflex in fighter pilots with the video head impulse test.

CONCLUSION: There were no changes in the function of the six semicircular canals in active fighter pilots, through the use of the video head impulse test (vHIT). These results suggest that the vestibuloocular reflex (VOR) works well at the high frequencies related to the natural head movements in this population. OBJECTIVES/HYPOTHESIS: The vestibular function in pilots has been reported as being different from that of other normal subjects. These differences are attributed to adaptation of the vestibuloocular reflex (VOR) or by habituation. These studies were conducted with caloric and/or rotatory tests and were limited to the lateral semicircular canals. The aim of the present study was to verify the occurrence of high frequency changes in the function of the six semicircular canals in active fighter pilots, through the use of the video head impulse test (vHIT). STUDY DESIGN: Cross-sectional design. METHODS: The subjects participating in this study were divided in three groups, according to their flight experience. The control group (Group 1) consisted of 20 soldiers with no experience of in-flight training. For the test subjects 14 fighter pilots were selected and divided into two groups. Group 2 included the pilots with 1000-2000 hours of flight experience and Group 3 included pilots with 2001-3000 hours of flight experience. They were all submitted to a video head impulse test and the gains of the six semicircular canals were analysed. RESULTS: There were significantly low gain values (p < 0,013) only in the left posterior semicircular canal in the control group as compared with the subject groups. However, there were no significant differences in gain values between the two groups of the active pilots.

The video head impulse test.

CONCLUSION: Additional research is needed to validate the importance of the video head impulse tests (vHIT), but it provides an important contribution to the evaluation of anterior and posterior semicircular canal disorders. OBJECTIVES: To share observations of the vHIT test in clinical neurotology and to discuss the significance of the study findings. METHODS: This study comprised 200 patients with a clinical history of vestibular disturbances who were submitted to a vHIT including all six semicircular canals. RESULTS: Abnormal responses of the anterior and posterior canals were found in several patients, either alone or combined with altered responses in the lateral canals. A unilateral hypoactive response of a posterior canal was found in a patient with a small vestibular schwannoma.