Brainstem auditory evoked potentials

Auditory evoked potentials (AEPs) are a subclass of Event-related potentials (ERPs). For AEPs, the "event" is a sound. AEPs (and ERPs) are very small electrical voltage potentials originating from the brain recorded from the scalp in response to an auditory stimulus (such as different tones, speech sounds, etc.). The AEPs that are recorded from the top of the head originate from structures within the brain (e.g., the auditory cortex, the auditory brainstem structures, the auditory VIIIth cranial nerve). They are very low in voltage: from 2-10 microvolts for cortical AEPs to much less than 1 microvolt from the deeper brainstem structures. Their low voltage combined with relatively high background electrical noise requires the use of highly sensitive amplifiers and computer averaging equipment

Over recent years AEP's have been used to develop a monitor to measure anaesthetic depth and to prevent awareness in surgery. The aepEX depth of anaesthesia monitor was developed by Professor Gavin Kenny and his team at Glasgow University and is manufactured in Braintree, Essex by Medical Device Management Ltd.