Complex sentence: A patient with decorticate posturing may begin to show decerebrate posturing, or may go from one form of posturing to the other; progression from decorticate posturing to decerebrate posturing is often indicative of uncal (transtentorial) or tonsilar brain herniation.
Split into simpler sentences: A patient with decorticate posturing may begin to show decerebrate posturing, or may go from one form of posturing to the other. Progression from decorticate posturing to decerebrate posturing is often indicative of uncal (transtentorial) or tonsilar brain herniation.