Topic: Brain Death
Subject: Medicine
A 35 year old man has been on life support systems for the past 48 hours following blunt head trauma. Which of the following is the most important criterion to declare the patient brain dead and to permit removal of life support systems?

A. Bedside EEG showing no electrical activity

B. Decorticate and decerebrate posturing

C. Failure to respond to electroconvulsive stimuli

D. Glasgow coma score of 3 or less

Please do not use chat terms. Example: avoid using "grt" instead of "great".