Brainstem Auditory Evoked Potentials
A brainstem auditory evoked potential (BAEP) is an evoked potential caused by an aural stimulus (a sound), usually a series of ‘clicks’. Electrodes positioned on the scalp record responses to the sounds; these are then observed as a reading on an electroencephalogram (EEG). Responses to aural stimuli originate from relay structures within the brainstem.
From the BAEP a neurologist is able to determine the time it takes for an aural stimulus to travel from the point at the inner ear where the physical sound is translated into a bioelectrical impulse, to the brainstem. From these readings the neurologist can get an idea whether the auditory nerve is functioning properly. For example, an acoustic neuroma (a benign tumour of the ear canal) can stretch or compress the auditory nerve resulting in a long time for the processing of aural stimuli.