What is the effect of AICA vasospasm on BAER?

When analyzing the effect of AICA (anterior inferior cerebellar artery) vasospasm on Brainstem Auditory Evoked Responses (BAER), it is essential to understand the relationship between vascular supply and the neural structures involved in auditory pathways. AICA supplies blood to regions of the brain involved in auditory processing, including the cochlea and the auditory pathways in the brainstem.

In the case of AICA vasospasm, the blood flow to these critical areas can become compromised. This often leads to a phenomenon where the BAER response is altered. Specifically, a vasospasm can impede the function of the auditory neural structures without completely disconnecting the cochlear output.

The observed effect during AICA vasospasm is a complete loss of all BAER waves except for the cochlear microphonics. The cochlear microphonic is a response generated by the outer hair cells in the cochlea, reflecting the initial response to sound. In the presence of vasospasm affecting the auditory pathways, the neural processing beyond the cochlea (which generates the BAER waves) is disrupted. Therefore, while the cochlear microphonics can still be elicited due to intact cochlear function, the subsequent brainstem waves are significantly diminished or absent