Which BAEP waveform cannot be recorded from the contralateral side?

The brainstem auditory evoked potential (BAEP) consists of a series of waves that represent the electrical activity of the auditory pathway from the cochlea to the brainstem. Each wave corresponds to the activation of specific anatomical structures along this pathway.

Wave 1 is generated by the electrical activity from the cochlea and the auditory nerve. Since Wave 1 is produced very close to the source of input (the cochlea) and is directly related to the ipsilateral ear (the side that is being stimulated), it cannot be recorded or observed from the contralateral side (the opposite ear). This wave reflects the integrity of the peripheral auditory system and the activity of the auditory nerve for stimuli presented to that specific ear.

In contrast, Waves 2, 3, and 4 arise from neuronal pathways that are situated more centrally within the auditory brainstem. These waves can be influenced by inputs from both ears due to the crossing of pathways in the auditory system. Therefore, they can be recorded from the contralateral side, making Wave 1 unique in this context.

Understanding the distinctions among these waves provides valuable insights into the functioning and connectivity of the auditory system, which is critical in clinical assessments.