Auditory middle latency responses (AMLR) monoaural and binaural in the elderly

Introduction: The increase in life expectancy of the population requires a different management of the needs of the elderly. In aging, degeneration of the physiological, functional and behavioral aspects occurs, as well as structural changes in the central pathways and deficits in binaural abilities, often responsible for communication difficulties. The Auditory Middle Latency Response is shown to be a useful auditory tool for central assessment in the elderly and allows an analysis of binaural hearing function at the cortical level. Objective: To investigate the auditory middle latency response, to analyze and to compare the unilateral and bilateral stimulation and binaural interaction in the elderly. Methodology: Descriptive and analytical cross-sectional study. In the first moment, the audiological assessment was performed to determine the hearing thresholds and to divide the subjects into 2 groups. Group 1 (G1): 20 individuals of both genders, from 60 years, healthy, without hearing loss and group 2 (G2) consisted of 20 individuals of both genders, from 60 years of age, healthy, with thresholds between 30 and 70 dBHL in frequencies of 4 to 8 kHz. Potential recording was performed using two-channel Bio-logic Evoked Potential System (EP) equipment, with unilateral stimulation (right ear, then left ear) and bilateral stimulation (simultaneous stimulation in both ears) and then calculated the Binaural Interaction Component. Descriptive analysis (average and standard deviation) and inferential data were performed, with the Shapiro-Wilk test for normality, followed by the Repeated-Measures and mixed-design ANCOVA to analyze the effect of the group, condition and interaction (group vs. condition) controlling the effect of covariate age. Results: When compared to unilateral and bilateral stimulation, the latency of Na in C3A1 was higher in the stimulation of the right ear in G2 with a significant effect of covariate age. In the Na-Pa amplitude was observed main group effect under stimulation of the right ear and recording in C3A1. Compared the channels of registers (C3A1 and C4A2) the Na component in the G1 obtained with the left ear stimulation and recorded in C4A2 presented higher latency, with covariate age effect. In the same group, the latency of the Pa component was higher in stimulation of the right ear and recorded at C4A2. The Pb component in the G2 obtained by bilateral stimulation and recorded at C4A2 presented higher latency with a significant effect for the age. The auditory middle latency response was a sensitive examination of the evaluation of the central auditory system of the elderly. Conclusion: The transmission of auditory information to the primary auditory cortex is impaired with aging, mainly in unilateral stimulation, reinforced by damages in the elderly with peripheral hearing loss, as in the binaural interaction at cortical and subcortical levels. (AU)