Thunderclap Headache

Thunderclap headache (TCH) is a medical emergency that requires prompt recognition and an immediate and thorough investigation in search for serious secondary causes that have the potential for neurological morbidity and death. Although a noncontrast computed tomography (CT) and cerebrospinal fluid (CSF) examination, if done within 24. h, is adequate to exclude aneurysmal subarachnoid hemorrhage, it is no longer the standard of care for the complete evaluation of TCH. All patients must have cerebrovascular imaging of the head and neck vessels as the majority of causes of TCH are vascular and not adequately assessed by routine CT head and CSF examinations. Reversible cerebral vasoconstriction syndrome (RCVS) is the most common cause of nonaneurysmal TCH and a high degree of suspicion is necessary to make the diagnosis as up to 20% of cases may not be evident on initial noninvasive angiography of the cerebral circulation. Close monitoring and a scheduled follow-up is necessary to make the diagnosis. Treatment in an attempt to avoid serious neurological morbidity involves the removal of inciting drugs if present, the avoidance of inciting triggers, and judicious use of medications, including calcium channel blockers. Although calcium channel blockers have become the standard of care, there have been no randomized controlled trials to evaluate their effectiveness. Future controlled studies, preferably multicenter and -national, will be required to adequately address the most effective and appropriate approach to the management of patients with TCH, in general, and RCVS in particular.