Evaluation of thunderclap headache (TCH)

CT: computed tomography; SAH: subarachnoid hemorrhage; LP: lumbar puncture; CSF: cerebrospinal fluid; MRI: magnetic resonance imaging; MRA: magnetic resonance angiography; MRV: magnetic resonance venography; RCVS: reversible cerebral vasoconstriction syndrome; PRES: posterior reversible encephalopathy syndrome, also known as RPLS (reversible posterior leukoencephalopathy syndrome); CTA: computed tomography angiography; CTV: computed tomography venography.
* Further evaluation to determine the cause of SAH, including neurovascular imaging, will be needed; refer to appropriate topic reviews.
¶ CT is less sensitive than MRI for all of the possible underlying causes of TCH. Follow-up MRI, MRA, and MRV is often indicated even if CT identifies a potential cause of TCH.
Δ Obtain brain MRI, MRA, and MRV if LP is contraindicated.
◊ Further evaluation for possible SAH may be necessary with CSF spectrophotometry and/or cerebral angiography; refer to appropriate topic reviews.
§ Obtain contrast-enhanced MRI of brain and cerebrovascular imaging with MRA and MRV. Obtain contrast-enhanced CT with CTA and CTV if MRI/MRA/MRV are not options.
¥ Up to 20% of noninvasive vascular angiograms are negative in RCVS. The existence of primary thunderclap headache is controversial; it is a diagnosis of last resort, reached only when all organic causes have been excluded by expedited and exhaustive search.