We have probably all struggled with these phenomena in our TBI patients in the neuro ICU: swinging blood pressures, episodic tachycardia and fever, occurring even several weeks after the initial traumatic event. In this article in the Lancet, Meyfroidt and colleagues offer us some insight into the clinical syndrome now known as paroxysmal sympathetic hyperreactivity. Only quite recently recognised, it is an important clinical entity that seems to affect a substantial proportion of TBI patients, while also contributing to mortality in this patient group.