Editing Headache (section)

=== Red flags ===
It can be challenging to differentiate between low-risk, benign headaches and high-risk, dangerous headaches since symptoms are often similar.<ref name="Abrams Journal">{{cite journal | vauthors = Abrams BM | title = Factors that cause concern | journal = The Medical Clinics of North America | volume = 97 | issue = 2 | pages = 225–242 | date = March 2013 | pmid = 23419623 | doi = 10.1016/j.mcna.2012.11.002 }}</ref> Headaches that are possibly dangerous require further lab tests and imaging to diagnose.<ref name="Clinch" />

The American College for Emergency Physicians published criteria for low-risk headaches. They are as follows:<ref name="ACEP Criteria">{{cite journal | author = American College of Emergency Physicians | title = Clinical policy: critical issues in the evaluation and management of patients presenting to the emergency department with acute headache | journal = Annals of Emergency Medicine | volume = 39 | issue = 1 | pages = 108–122 | date = January 2002 | pmid = 11782746 | doi = 10.1067/mem.2002.120125 }}</ref>
* age younger than 30 years
* features typical of primary headache
* history of similar headache
* no abnormal findings on neurologic exam
* no concerning change in normal headache pattern
* no high-risk comorbid conditions (for example, HIV)
* no new concerning history or physical examination findings

A number of characteristics make it more likely that the headache is due to potentially dangerous secondary causes which may be life-threatening or cause long-term damage. These "red flag" symptoms mean that a headache warrants further investigation with neuroimaging and lab tests.<ref name="Clinch" />

In general, people complaining of their "first" or "worst" headache warrant imaging and further workup.<ref name="Clinch" /> People with progressively worsening headache also warrant imaging, as they may have a mass or a bleed that is gradually growing, pressing on surrounding structures and causing worsening pain.<ref name="Abrams Journal" /> People with neurological findings on exam, such as weakness, also need further workup.<ref name="Abrams Journal" />

The American Headache Society recommends using "SSNOOP", a mnemonic to remember the red flags for identifying a secondary headache:<ref name="Smetana">{{cite book | chapter-url = http://accessmedicine.mhmedical.com/content.aspx?bookid=500&sectionid=41026552 | vauthors = Smetana GW | chapter = Chapter 9. Headache. | veditors = Henderson MC, Tierney Jr LM, Smetana GW | title = The Patient History: An Evidence-Based Approach to Differential Diagnosis | location = New York, NY | publisher = McGraw-Hill | date = 2012 | archive-url = https://web.archive.org/web/20150531030403/http://accessmedicine.mhmedical.com/content.aspx?bookid=500&sectionid=41026552 |archive-date = 31 May 2015 }}</ref>
* Systemic symptoms (fever or weight loss)
* Systemic disease (HIV infection, malignancy)
* Neurologic symptoms or signs
* Onset sudden (thunderclap headache)
* Onset after age 40 years
* Previous headache history (first, worst, or different headache)

Other red flag symptoms include:<ref name="Clinch" /><ref name="Smetana" /><ref name="Abrams Journal" /><ref name="Hainer">{{cite journal | vauthors = Hainer BL, Matheson EM | title = Approach to acute headache in adults | journal = American Family Physician | volume = 87 | issue = 10 | pages = 682–687 | date = May 2013 | pmid = 23939446 }}</ref>
{|class="wikitable"
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! Red Flag !! Possible causes !! The reason why a red flag indicates possible causes !! Diagnostic tests
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| New headache after age 50 || Temporal arteritis, mass in brain || Temporal arteritis is an inflammation of vessels close to the temples in older people, which decreases blood flow to the brain and causes pain. May also have tenderness in temples or jaw claudication. Some brain cancers are more common in older people. || Erythrocyte sedimentation rate (diagnostic test for temporal arteritis), neuroimaging
|-
| Very sudden onset headache ([[thunderclap headache]]) || Brain bleed ([[subarachnoid hemorrhage]], hemorrhage into mass lesion, [[vascular malformation]]), [[pituitary apoplexy]], mass (especially in [[Posterior cranial fossa|posterior fossa]]) || A bleed in the brain irritates the meninges which causes pain. Pituitary apoplexy (bleeding or impaired blood supply to the pituitary gland at the base of the brain) is often accompanied by double vision or visual field defects, since the pituitary gland is right next to the [[optic chiasm]] (eye nerves). || [[Neuroimaging]], [[lumbar puncture]] if computed tomography is negative
|-
| Headaches increasing in frequency and severity || Mass, subdural hematoma, medication overuse || As a brain mass gets larger, or a [[subdural hematoma]] (blood outside the vessels underneath the [[Dura mater|dura]]) it pushes more on surrounding structures causing pain. Medication overuse headaches worsen with more medication taken over time. || Neuroimaging, drug screen
|-
| New onset headache in a person with possible HIV or cancer || [[Meningitis]] (chronic or carcinomatous), [[brain abscess]] including [[toxoplasmosis]], [[metastasis]] || People with HIV or cancer are immunosuppressed so are likely to get infections of the meninges or infections in the brain causing abscesses. Cancer can metastasize, or travel through the blood or lymph to other sites in the body. || Neuroimaging, lumbar puncture if neuroimaging is negative
|-
| Headache with signs of total body illness (fever, stiff neck, rash) || [[Meningitis]], [[encephalitis]] (inflammation of the brain tissue), [[Lyme disease]], [[collagen vascular disease]] || A stiff neck, or inability to flex the neck due to pain, indicates inflammation of the meninges. Other signs of systemic illness indicates infection. || Neuroimaging, lumbar puncture, serology (diagnostic blood tests for infections)
|-
| [[Papilledema]] || Brain mass, [[benign intracranial hypertension]] (pseudotumor cerebri), [[meningitis]] || Increased intracranial pressure pushes on the eyes (from inside the brain) and causes papilledema. || Neuroimaging, lumbar puncture
|-
| Severe headache following head trauma || Brain bleeds ([[intracranial hemorrhage]], [[subdural hematoma]], [[epidural hematoma]]), post-traumatic headache || Trauma can cause bleeding in the brain or shake the nerves, causing a post-traumatic headache || Neuroimaging of brain, skull, and possibly cervical spine
|-
| Inability to move a limb || Arteriovenous malformation, collagen vascular disease, intracranial mass lesion || Focal neurological signs indicate something is pushing against nerves in the brain responsible for one part of the body || Neuroimaging, blood tests for collagen vascular diseases
|-
| Change in personality, consciousness, or mental status || [[Central nervous system infection]], [[Intracranial bleeding|intracranial bleed]], mass || Change in mental status indicates a global infection or inflammation of the brain, or a large bleed compressing the brainstem where the consciousness centers lie || Blood tests, lumbar puncture, neuroimaging
|-
| Headache triggered by cough, exertion or while engaged in sexual intercourse || Mass lesion, subarachnoid hemorrhage || Coughing and exertion increases the intra cranial pressure, which may cause a vessel to burst, causing a subarachnoid hemorrhage. A mass lesion already increases intracranial pressure, so an additional increase in intracranial pressure from coughing etc. will cause pain. || Neuroimaging, lumbar puncture
|-
|}