Cerebral signs (confusion, restlessness, agitation) in HS and CS are indicative of imminent circulatory collapse. Thanks to an ingenious distribution of α receptors in the body that leaves the brain auto-regulation unaffected by systemic mechanisms of protection until the end after having benefited indirectly by the maintenance of systemic pressures by systemic mechanisms, brain involvement in HS/CS is the last ditch, the last resort before collapse. In IS toxins and inflammatory mediators irritate the brain at any stage.