+ Differential diagnosis of headaches Tension headache New daily persistent headache Cluster headache Migraine mild to moderate dull or aching pain severe pain moderate to severe pain duration of 30 minutes to several hours duration of at least four hours daily duration of 30 minutes to 3 hours duration of 4 hours to 3 days Occur in periods of 15 days a month for three months may happen multiple times in a day for months periodic occurrence; several per month to several per year located as tightness or pressure across head located on one or both sides of head located one side of head focused at eye or temple located on one or both sides of head consistent pain pain describable as sharp or stabbing pulsating or throbbing pain no nausea or vomiting nausea, perhaps with vomiting no aura no aura auras uncommonly, light sensitivity or noise sensitivity may be accompanied by running nose, tears, and drooping eyelid, often only on one side sensitivity to movement, light, and noise exacerbated by regular use of acetaminophen or NSAIDS may exist with tension headache Most headaches can be diagnosed by the clinical history alone. If the symptoms described by the person sound dangerous, further testing with neuroimaging or lumbar puncture may be necessary. Electroencephalography (EEG) is not useful for headache diagnosis. The first step to diagnosing a headache is to determine if the headache is old or new. A "new headache" can be a headache that has started recently, or a chronic headache that has changed character. For example, if a person has chronic weekly headaches with pressure on both sides of his head, and then develops a sudden severe throbbing headache on one side of his head, they have a new headache. Red flags It can be challenging to differentiate between low-risk, benign headaches and high-risk, dangerous headaches since symptoms are often similar. Headaches that are possibly dangerous require further lab tests and imaging to diagnose. The American College for Emergency Physicians published criteria for low-risk headaches. They are as follows: * 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. In general, people complaining of their "first" or "worst" headache warrant imaging and further workup. 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. People with neurological findings on exam, such as weakness, also need further workup. The American Headache Society recommends using "SSNOOP", a mnemonic to remember the red flags for identifying a secondary headache: * 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: Red Flag Possible causes Reason why red flag indicates possible causes Diagnostic tests 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 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) 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 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 Old headaches Old headaches are usually primary headaches and are not dangerous. They are most often caused by migraines or tension headaches. Migraines are often unilateral, pulsing headaches accompanied by nausea or vomiting. There may be an aura (visual symptoms, numbness or tingling) 30–60 minutes before the headache, warning the person of a headache. Migraines may also not have auras. Tension type headaches usually have bilateral "bandlike" pressure on both sides of the head usually without nausea or vomiting. However, some symptoms from both headache groups may overlap. It is important to distinguish between the two because the treatments are different. The mnemonic 'POUND' helps distinguish between migraines and tension type headaches. POUND stands for: One review article found that if 4–5 of the POUND characteristics are present, migraine is 24 times as likely a diagnosis than tension type headache (likelihood ratio 24). If 3 characteristics of POUND are present, migraine is 3 times more likely a diagnosis than tension type headache (likelihood ratio 3). If only 2 POUND characteristics are present, tension type headaches are 60% more likely (likelihood ratio 0.41). Another study found the following factors independently each increase the chance of migraine over tension type headache: nausea, photophobia, phonophobia, exacerbation by physical activity, unilateral, throbbing quality, chocolate as headache trigger, cheese as headache trigger. Cluster headaches are relatively rare (1 in 1000 people) and are more common in men than women. They present with sudden onset explosive pain around one eye and are accompanied by autonomic symptoms (tearing, runny nose and red eye). Temporomandibular jaw pain (chronic pain in the jaw joint), and cervicogenic headache (headache caused by pain in muscles of the neck) are also possible diagnoses. For chronic, unexplained headaches, keeping a headache diary can be useful for tracking symptoms and identifying triggers, such as association with menstrual cycle, exercise and food. While mobile electronic diaries for smartphones are becoming increasingly common, a recent review found most are developed with a lack of evidence base and scientific expertise. New headaches New headaches are more likely to be dangerous secondary headaches. They can, however, simply be the first presentation of a chronic headache syndrome, like migraine or tension-type headaches. One recommended diagnostic approach is as follows. If any urgent red flags are present such as visual loss, new seizures, new weakness, new confusion, further workup with imaging and possibly a lumbar puncture should be done (see red flags section for more details). If the headache is sudden onset (thunderclap headache), a computed tomography test to
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