Cerebral vasoconstriction, headache and sometimes stroke: one syndrome or many?

In this issue, Dr Ducros, Professor Bousser and others from the Lariboisiere hospital in Paris report the largest case series to date on the so-called ‘reversible cerebral vasoconstriction syndrome’, or RCVS (Ducros et al. , 2007, p. 3091.). The two key features of the syndrome are ‘thunderclap headaches’ and multifocal but transient narrowing of cerebral arteries. In addition, ischaemic or haemorrhagic stroke may supervene. The authors specify this further in that the headache should come on within a minute (less often within 5 min) and should be unusually severe; generally there are several similar episodes over a period of days or weeks. The angiographic signs of arterial narrowing disappear within a few weeks or months. Specific other conditions are ruled out by standard investigations of the brain, serum and cerebrospinal fluid. The authors not only carefully list the range of each symptom and angiographic feature within their group of 67 patients but also, thanks to the prospective study design, they tabulate possible precipitating factors and include a follow-up period in order to demonstrate the episodic nature of the disorder. Before addressing the robustness of these definitions, I shall make a short detour to reflect briefly on the rise and fall of ‘vasospasm’ as an explanation for vascular disorders of the brain, and also address the question of what actually constitutes any nosological entity.Arterial spasm as a cause of gangrene of the extremities was described by Raynaud (1834–1881) in his doctoral thesis (Raynaud, 1862). Others extrapolated his theory of vasospasm to the cerebral circulation in order to explain transient episodes of cerebral ischaemia. Even the great Osler mounted the bandwagon to explain transient attacks of aphasia and paralysis: ‘We have plenty of evidence that arteries may pass into a state of spasm with obliteration of the lumen and loss …