Acute Headache Imaging

Obtain urgent cranial imaging when headache is abrupt and severe, new or progressive, or associated with fever, impaired consciousness, focal neurologic deficit, seizure, meningeal signs, visual disturbance, papilledema, exertional provocation, pregnancy or puerperium, cancer, coagulopathy, immunosuppression, or trauma. These findings redirect evaluation from a primary-headache pathway toward hemorrhagic, infectious, vascular, mass-effect, or pressure-related disease. PubMed+1PubMedThe Value of Cranial CT Imaging in Patients With Headache at the Emergency DepartmentPubMedAtypical Cause of Headache: A Potential Diagnostic Pitfall in Acute Medicine - PMC

Before imaging, document onset-to-peak time, time of onset, prior pattern, trauma, vasoactive or toxic exposure, anticoagulation or coagulopathy, pregnancy/postpartum state, cancer and immunosuppression, fever, neck stiffness, and positional symptoms. Perform vital signs, a complete neurologic examination, fundoscopy when feasible, and targeted ocular examination for red eye, pupillary abnormality, peri-orbital pain, or visual complaints. PubMedPubMedAtypical Cause of Headache: A Potential Diagnostic Pitfall in Acute Medicine - PMC

Do not routinely image a patient with an established migraine pattern, normal neurologic examination, and no new symptoms or red flags. New fever, seizure, trauma, or substantial change in a persistent headache pattern is an exception and should reopen secondary-cause evaluation. ScienceDirectScienceDirect“Worst Headache of Life” in a Migraineur: Marginal Value of Emergency Department CT Scanning - ScienceDirect

Order noncontrast head CT immediately for thunderclap headache because it is the imaging modality of choice for acute subarachnoid hemorrhage and is superior to MRI for detecting acute subarachnoid blood. If CT shows subarachnoid or parenchymal hemorrhage, proceed to vascular evaluation for aneurysm or vascular malformation. ScienceDirectScienceDirectThunderclap headache: Diagnostic considerations and neuroimaging features

For an adult ED patient, ACEP specifically evaluates whether a normal noncontrast CT performed within 6 hours of headache onset can preclude further diagnostic workup for subarachnoid hemorrhage. The timing must be established accurately; a normal CT obtained later, or a clinical picture with persisting high concern, should not be treated as equivalent. annemergmed+1annemergmedClinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Acute HeadachePubMedThe Value of Cranial CT Imaging in Patients With Headache at the Emergency Department

When CT is normal but subarachnoid hemorrhage remains clinically suspected, perform lumbar puncture with opening pressure, red and white blood cell counts, protein, glucose, and spectrophotometry for xanthochromia. In the absence of another indication such as meningitis, delay LP for at least 6 hours and preferably 12 hours after headache onset to permit xanthochromia detection. PubMedPubMedNeuroimaging and other investigations in patients presenting with headache

Use MRI when noncontrast CT is unrevealing but the phenotype suggests a lesion CT may miss, including intracranial-pressure disorders, infection, ischemia, posterior reversible encephalopathy syndrome, or pituitary apoplexy. In patients with acute headache and red flags, lumbar puncture or MRI is warranted when the initial CT does not resolve the diagnostic concern. PubMed+1PubMedThe Value of Cranial CT Imaging in Patients With Headache at the Emergency DepartmentPubMedPituitary Apoplexy - StatPearls - NCBI Bookshelf

Use CTA or MRA when arterial pathology is suspected. Recurrent thunderclap headache, especially over days to weeks, should prompt CTA or MRA for the multifocal “string of beads” pattern of RCVS. Early angiography may be negative, so an initially normal vascular study does not definitively eliminate RCVS when the clinical syndrome remains compelling. PubMed+1PubMedNeuroimaging and other investigations in patients presenting with headachePubMedReversible cerebral vasoconstriction syndrome associated with probable drug poisoning - PMC

Use CT venography or MR venography when cerebral venous thrombosis is a plausible cause, particularly in pregnancy or puerperium or when headache occurs with other red flags. Conventional CT may be normal in conditions requiring venographic imaging. PubMed+2PubMedThe Value of Cranial CT Imaging in Patients With Headache at the Emergency DepartmentPubMedAtypical Cause of Headache: A Potential Diagnostic Pitfall in Acute Medicine - PMCScienceDirectCerebral venous thrombosis presenting with subarachnoid hemorrhage: Case report and review - ScienceDirect

Perform lumbar puncture promptly for suspected meningitis; do not delay CSF testing when the presentation includes fever, altered mental status, meningeal signs, focal neurologic deficits, HIV, or other immunocompromise and the diagnostic pathway supports CNS infection. PubMed+1PubMedNeuroimaging and other investigations in patients presenting with headachePubMedAcute Headache - StatPearls - NCBI Bookshelf

After normal CT in suspected subarachnoid hemorrhage, LP should include opening pressure, red and white cells, protein, glucose, and spectrophotometry for xanthochromia. For the isolated subarachnoid hemorrhage question, obtain CSF no sooner than 6 hours and preferably 12 hours from headache onset unless another diagnostic indication requires earlier LP. PubMedPubMedNeuroimaging and other investigations in patients presenting with headache

Measure opening pressure whenever LP is used to investigate a pressure syndrome. Elevated opening pressure is diagnostically important when idiopathic intracranial hypertension is suspected, while an orthostatic phenotype should raise concern for low-pressure headache even if the positional feature has attenuated. PubMed+1PubMedAcute Headache - StatPearls - NCBI BookshelfPubMedNeuroimaging and other investigations in patients presenting with headache

For pituitary apoplexy, treat acute adrenal insufficiency as the immediate life-threatening complication. In a patient with abrupt severe headache, visual field loss, ophthalmoplegia, nausea or vomiting, altered consciousness, or hemodynamic instability, obtain urgent MRI and administer high-dose corticosteroids while arranging neurosurgical, endocrine, and ophthalmologic evaluation; assess for surgical decompression when indicated. PubMedPubMedPituitary Apoplexy - StatPearls - NCBI Bookshelf

For PRES, image patients with headache plus encephalopathy or seizures in the setting of hypertension, renal failure, immunosuppressive medications, or autoimmune disease. Management includes removing precipitants and gradually reducing blood pressure by no more than 20% over 1 to 2 hours; use titratable agents to minimize blood-pressure variability. acepacep[PDF] Race Against Time Sticks and Stones - ACEP

For RCVS, exclude competing hemorrhagic and vascular diagnoses before assigning the syndrome. CTA, MRA, or angiography demonstrating multifocal narrowing supports the diagnosis, but confirmation requires documented reversal within 12 weeks; differentiate from primary angiitis of the CNS, which more often has an insidious headache course. PubMed+1PubMedReversible cerebral vasoconstriction syndrome associated with probable drug poisoning - PMCPubMedReversible cerebral vasoconstriction syndrome: literature review