Auditory Middle Latency Responses: Different Register Derivations

Introduction: The auditory middle latency responses are bioelectrical answers to the auditive neurofunctional evaluation in patients with central auditive nervous system injuries and dysfunctions. Therefore, two active register canals were used to set electrodes in the right and left hemispheres and, when the right and left ears are stimulated, there are counter lateral and ipsilateral registers. It is not clear in the literature, which electrodes disposition gives the better answer.

Objective: The study aimed to compare the auditive potential evoked registers obtained from the electrodes C3/A2, C4/A1, and C3/A1 in relation to the right and the left ears.

Methods: This study is of transversal type with quantitative and qualitative delineation. A total of 10 healthy children's (without audiological and neurological alterations) registers were analyzed in C3 and C4 (left and right hemispheres) positions with reference to A1 and A2 ears (left and right earlobes) and ground electrode on the forehead, matched ipsilaterally and counterlaterally, alternating the right and left ears. For statistical analysis, the Student t test and Statistics 7.0 statistic program were used.

Results and Conclusion: Smaller latency in Na component in C3/A2 was observed when compared with C3/A1, when the right ear was stimulated. Better results in the earlobe A2 (right earlobe) proximal field were obtained by the right ear stimulation. This finding suggests that the nearer the electric field is from the generative source, the smaller the latency will be of its components. However, more studies are suggested so that such findings can be confirmed.

Keywords: hearing, electrophysiology, child.