%0 Journal Article %T Reversible Cerebral Vasoconstriction Syndrome: An Important Cause of Acute Severe Headache %A Li Huey Tan %A Oliver Flower %J Emergency Medicine International %D 2012 %I Hindawi Publishing Corporation %R 10.1155/2012/303152 %X Reversible cerebral vasoconstriction syndrome (RCVS) is an increasingly recognized and important cause of acute headache. The majority of these patients develop potentially serious neurological complications. Rigorous investigation is required to exclude other significant differential diagnoses. Differentiating RCVS from subarachnoid haemorrhage (SAH) and primary angiitis of the central nervous system (PACNS) may be difficult but has important therapeutic implications. This paper describes what is currently known about the epidemiology, pathophysiology, clinical, and diagnostic features of the syndrome, an approach to investigation, a summary of treatments, and what is known of prognosis. 1. Introduction Acute severe headache presenting to the Emergency Department (ED) accounts for 1-2% of admissions [1]. Whilst the differential diagnosis in the setting of nontraumatic headache is extensive, it is imperative that life-threatening causes of headache are identified in a timely fashion and treated appropriately. Reversible cerebral vasoconstriction syndrome (RCVS) is one of these differentials that potentially has dire consequences and, with improving technology and awareness, is being increasingly diagnosed. The presence of acute severe headache and characteristic angiographic findings was initially described in a case series in which Gregory Call and Marie Fleming were lead authors, hence the eponym Call-Fleming syndrome [2]. They described unique features in patients who presented with sudden onset severe headache and cerebral angiography that demonstrated reversibility of vasoconstriction of arteries involving the Circle of Willis and its immediate branches [2]. Other literature has described similar clinical entities that appear to fall under the descriptive heading of RCVS. This includes migrainous vasospasm or migraine angiitis [3¨C5], benign angiopathy of the central nervous system [6], postpartum angiopathy [7], thunderclap headache with reversible vasospasm [3¨C5], and drug-induced angiopathy [7, 8]. Distinguishing all of these disorders from cerebral vasculitis has also been challenging but is a key diagnostic step as the treatments are significantly different. The unifying term reversible cerebral vasoconstriction syndrome (RCVS) was proposed by Calabrese in 2007 [9]. It encompasses all of these clinical entities, which share similar clinical presentations, radiological findings, and sequelae. The diagnostic elements of RCVS are shown in Table 1. Table 1: Diagnostic criteria for RCVS [ 9]. Since the initial descriptions in 1988, much remains %U http://www.hindawi.com/journals/emi/2012/303152/