What auditory wave is typically the last to occur during BAER testing?

In Brainstem Auditory Evoked Response (BAER) testing, Wave V is generally recognized as the last wave to occur. This waveform is produced by the activity in the auditory pathways, specifically from the lateral lemniscus and inferior colliculus in the brainstem, indicating the culmination of auditory processing within these areas. As auditory stimuli are presented, the sequence of waves recorded reflects the transmission of sound information through the auditory pathway, with Wave I originating from the auditory nerve, and subsequent waves resulting from processing at various brainstem nuclei.

Wave V emerges later in the sequence due to its generation further along the auditory pathway compared to earlier waves, which are produced by more peripheral structures. This makes Wave V critical for assessing the integrity of the auditory pathway, particularly in the brainstem. Its identification is essential during surgical procedures where auditory function preservation is vital, as inducing an abnormality or loss of this wave can indicate potential neural compromise or injury.

The other waves, such as I, III, and IV, occur earlier in the BAER response, reflecting activity in progressively more peripheral sites within the auditory system, and therefore do not represent the final processing event assessed in this testing format.