The study aimed to investigate baroreceptor reflex sensitivity in a patient with head injury for whom plateau waves of intracranial pressure (ICP) were recorded. Baroreflex sensitivity index was separately estimated on top of plateau waves and during intermediate intervals between two consecutive waves. The EuroBaVar data set was utilized to verify and validate the results. A very high baroreflex sensitivity associated with dominant parasympathetic activity was observed spontaneous to the acute elevations of ICP. The high vagal afferent discharge was found to be suggestive for the high firing rate of carotid baroreceptors and probably an active Cushing reflex mechanism during plateau waves