Surgical repair of aortic aneurysms carries substantial risks due to interruption of blood flow to certain structures within the body. During the repair of thoracoabdominal aortic aneurysms (TAAA) in the descending aorta one such structure at risk is the spinal cord. IONM of motor and sensory pathways can alert the team that blood flow to the spinal cord has been compromised and requires urgent attention to prevent a permanent neurological deficit developing.

In contrast to this during the repair of the ascending aorta blood supply to the brain is deliberately suspended for a time in order for the graft to be positioned.

IONM using Electroencephalography (EEG) provides two roles in this instance. Firstly providing valuable information regarding the efficacy of induced hyperthermia for brain protection. Secondly monitoring the cortical activity following completion of grafting, provides the surgeon with valuable information about the return of cortical activity and any potential problems developing.