title: Nonaneurysmal thunderclap headache with diffuse, multifocal, segmental, and reversible vasospasm.
abstract: OBJECTIVE
  To highlight the clinical profiles and angiographic findings of two patients with recurrent thunderclap headache (TCH) without subarachnoid hemorrhage (SAH) and to present modified diagnostic criteria for this unusual syndrome.
  
  
  BACKGROUND
  TCH may be a benign recurrent headache disorder or it may represent a serious underlying process such as SAH or venous sinus thrombosis. The pathophysiology of this disorder in the absence of underlying pathology is not well understood and its potential angiographic features are not well appreciated.
  
  
  METHODS
  Two case descriptions with illustrative angiography.
  
  
  RESULTS
  Both cases demonstrated the potential for reversible intracranial vasospasm without intracranial aneurysm or SAH and a benign clinical outcome.
  
  
  CONCLUSIONS
  Primary TCH has a distinctive clinical and angiographic profile and must be distinguished from central nervous system vasculitis and SAH.
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Dodick
authors.forename: R D
authors.initials: RD
authors.lastname: Brown
authors.forename: J W
authors.initials: JW
authors.lastname: Britton
authors.forename: J
authors.initials: J
authors.lastname: Huston
mesh_terms: D006261:Headache / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D002532:Intracranial Aneurysm / Q000503:physiopathology*; D002546:Ischemic Attack, Transient / Q000473:pathology / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged