A novel method of brainstem auditory evoked potentials using complex verbal stimuli.

ABSTRACT

BACKGROUND: The click and tone-evoked auditory brainstem responses are widely used in clinical practice due to their consistency and predictability. More recently, the speech-evoked responses have been used to evaluate subcortical processing of complex signals, not revealed by responses to clicks and tones. AIMS: Disyllable stimuli corresponding to familiar words can induce a pattern of voltage fluctuations in the brain stem resulting in a familiar waveform, and they can yield better information about brain stem nuclei along the ascending central auditory pathway. MATERIALS AND METHODS: We describe a new method with the use of the disyllable word "baba" corresponding to English "daddy" that is commonly used in many other ethnic languages spanning from West Africa to the Eastern Mediterranean all the way to the East Asia. RESULTS: This method was applied in 20 young adults institutionally diagnosed as dyslexic (10 subjects) or light dyslexic (10 subjects) who were matched with 20 sex, age, education, hearing sensitivity, and IQ-matched normal subjects. The absolute peak latencies of the negative wave C and the interpeak latencies of A-C elicited by verbal stimuli "baba" were found to be significantly increased in the dyslexic group in comparison with the control group. CONCLUSIONS: The method is easy and helpful to diagnose abnormalities affecting the auditory pathway, to identify subjects with early perception and cortical representation abnormalities, and to apply the suitable therapeutic and rehabilitation management.