Estímulos acústicos naturais de fala e dispositivo acessório para diagnóstico de alterações auditivas centrais em pacientes com microcefalia

Abstract

Introduction: Patients with microcephaly are at greater risk for developing central hearing loss and for diagnosis it is necessary to use cortical auditory evoked potentials that can be optimized through natural speech acoustic stimuli. However, in clinical and research practices, it is difficult to insert new acoustic stimuli in the available equipment; they are designed to be used only with the stimuli provided by their manufacturers. Objective: To develop natural acoustic speech stimuli and an accessory device for diagnosis of central hearing loss in patients with microcephaly. Methods: Through the software Praat® natural speech stimuli were filed in wav format. With the developed stimuli (/ba/ e /ma/), randomized 1: 1, cortical auditory evoked potentials were elicited in 15 children (G1 controls) and 15 children with microcephaly (G2) and recorded in both cerebral hemispheres. Kolmogorov-Smirnov test was used and, according to the data distribution of each variable, parametric or nonparametric tests were used for independent samples (T-Student and Mann-Whitney, respectively). Results: The natural speech stimuli /ba/ (duration: 180ms, voice onset time - VOT of -70ms), / da / (duration: 180ms, VOT of -79ms) and / ma / (duration: 180ms) were created. Through the stimulus /ba/, in children with microcephaly, higher P2 amplitudes than controls in the left brain hemisphere (p = 0.018) and higher N2 amplitudes in both brain hemispheres (p = 0.040 and 0.021, right and left, respectively) were observed. Through the stimulus /ma/, G2 presented higher P1 amplitudes than G1 in both brain hemispheres (p = 0.011 and 0.005, right and left, respectively); higher P3 latencies in both brain hemispheres (p = 0.045 and 0.011, right and left, respectively). Conclusion: The acoustic speech stimuli were compatible with research practices in the diagnostic innovation of central hearing loss in patients with microcephaly by eliciting cortical auditory evoked potentials whose patterns were compatible with auditory cortical immaturity that compromises the detection and inhibitory control processes of acoustic stimuli.