Basilar migraine: polarity-dependent alteration of brainstem auditory evoked potential.

We studied serial brainstem auditory evoked potentials (BAEPs) in a patient who had episodic basilar migraine. During migraine attack, significant alteration of wave IV-V was revealed only by rarefaction clicks. The alteration remained unchanged throughout the headache and reverted to normal when the headache subsided. In contrast, BAEPs with condensation clicks were normal during and after the headache.