An implantable neurostimulator device for implantation in a head of a patient includes a housing adapted to be implanted beneath a patient's scalp, and a cardiac monitoring element, a brain monitoring element, and a processor. The processor is configured to receive a cardiac signal from the cardiac monitoring element, identify cardiac events in the cardiac signal, receive a brain signal from the brain monitoring element, identify neurological events in the brain signal, and indicate a relationship between the neurological events and the cardiac events.