- Clinical science
Headache is a symptom commonly encountered in everyday clinical practice, and, according to the WHO, one of the ten most common causes of functional disability. It may be primary (e.g., tension-type headaches, migraine) or secondary (e.g., following head trauma or infections) in nature. Although most episodes of headache are harmless, potentially life-threatening causes (e.g., subarachnoid hemorrhage, meningitis) should always be considered. Identifying the cause of headaches is often difficult and requires a detailed clinical history as well as a thorough physical examination. Additional diagnostics, e.g., imaging, are only indicated if headaches persist despite treatment or if specific clinical features are present that are signs of an underlying disease. This article gives an overview of the most common types of headache and serves as a guide to diagnosing different headache disorders.
Approach to management
- Check vital signs.
- Perform focused history and examination.
- If red flags are present:
- Obtain brain imaging (either CT or MRI brain with and/or without contrast) based on the red flag symptoms. 
- Perform further targeted diagnostics (see below).
- If no red flags are present and suspicion for life-threatening causes is low:
- Perform a detailed history and clinical exam.
- Consider whether further diagnostic testing is necessary.
- Provide supportive care.
- Identify and treat the underlying cause.
- Sudden-onset severe headache (e.g., ”thunderclap headache”)
- Focal neurological deficits
- New headache at age > 50
- Progressively worsening headache
- Immunodeficiency (especially HIV)
- Meningeal signs
- Psychiatric symptoms
- Failure to respond to analgesics
- “Worst headache of my life”
- Visual deficits
- Pregnancy or postpartum period
- Signs of increased ICP (e.g., papilledema)
- Confusion or impaired level of consciousness
Life-threatening conditions 
- Intracranial hemorrhage: subarachnoid hemorrhage, epidural hemorrhage, intracerebral hemorrhage
- CNS infection: meningitis, encephalitis, brain abscess, subdural empyema
- Conditions causing increased ICP
- Hypertensive emergency
- Internal carotid artery dissection
- Vertebral artery dissection
- Ischemic stroke
- Pituitary apoplexy
- Carbon monoxide poisoning
- Cerebral venous sinus thrombosis
- Pre-eclampsia or eclampsia
- Non-life-threatening conditions requiring urgent attention:
- Primary headache: a headache that is not caused by another underlying condition 
- Secondary headache: a headache that is caused by another underlying condition (e.g., trauma, space-occupying lesion) 
See “differential diagnoses” below.
- Duration of a single episode
- Clinical course (e.g., chronic, acute)
Nature of the headache
- Radiation of pain
- Severity (e.g., impact on patient's life)
- Triggers and exacerbating factors
- Associated symptoms
- Past medical history (e.g., hypertension, hypothyroidism, seizures, migraine, infections)
- Medications (e.g., anticoagulants , analgesics, OCPs)
- Caffeine intake
- Substance use
- Alcohol consumption
- Family history
- Blood pressure
- Presence of fever
- Signs of trauma
- Auscultation for bruits
- Palpation of pericranial muscles
- Palpation of the temporal artery; and assessment of jaw movement
- Palpation along the course of the trigeminal nerve
- Examination of the teeth and oral cavity
- Examination of the eye and extraocular movements
- Assessment of cervical spine mobility
- Palpation of the sinuses
- for neurologic deficits
- Signs of
- Abdomen: inspection and palpation of the abdomen
- Skin: : Evaluate for rash or signs of drug use.
Consider secondary life-threatening causes if red flags for headache are present!
- Diagnostic evaluation should be performed based on risk stratification and the suspected diagnosis.
- Low-risk headache: No routine laboratory tests or imaging are recommended.
- High-risk headache: Consider diagnostic workup based on the suspected diagnosis.
- Primary headache is a clinical diagnosis and typically does not require laboratory or imaging evaluation.
Risk stratification of headache 
- There are no routine recommended laboratory studies for headaches. Consider the following based on clinical suspicion:
- For emergency neuroimaging
- For urgent (arranged prior to discharge) neuroimaging in the emergency department:
- Patients > 50 years old with a new type of headache but normal neurologic examination
- In all other situations, imaging should be considered based on the suspected diagnosis and risk stratification.
- Test of choice
- The initial test of choice is usually a head CT without contrast.
- See the table below for other imaging modalities to consider.
|Recommended initial imaging modality for headache |
|Initial test of choice||Alternatives|
|Sudden-onset severe headache (i.e., thunderclap headache)|| || |
|New headache with papilledema|| || |
|New or worsening headache related to head trauma or accompanied by red flags|| || |
New primary headache suspected to be of trigeminal autonomic origin
(e.g., cluster headache)
| || |
|Chronic headache with new features or change in character, severity, or frequency|| || |
Additional diagnostics to consider 
- Lumbar puncture (LP) with CSF analysis: for suspected meningitis, suspected inflammatory process or malignancy, or if there is a high suspicion of SAH without proof on CT scan
- Tonometry: if increased intraocular pressure is suspected
- EEG: for any form of suspected seizures or complex migraine
- Temporal artery biopsy: if GCA is suspected
The diagnostic modality should be determined by the patient history and clinical presentation. Neuroimaging is usually not indicated for primary or low-risk headaches.
|Tension headache||Migraine headache||Cluster headache|
|Sex|| || || |
|Duration|| || || |
|Frequency|| || || |
|Localization|| || || |
|Character|| || || |
|Intensity|| || |
|Additional symptoms|| |
|Triggers/exacerbating factors|| || |
|Diagnostic findings|| || || |
The typical migraine headache can be remembered by “POUND”: pulsatile, one-day duration, unilateral, nausea, disabling intensity.
|Diagnosis||Clinical features||Diagnostic findings||Acute management|
|Intracerebral hemorrhage || |
|Subarachnoid hemorrhage |
|Subdural hematoma (SDH)|| || || |
|Epidural hematoma || |
|Cerebral venous sinus thrombosis || |
|Hypertensive crises |
|Ischemic stroke || |
|Intracranial space-occupying lesions (e.g., ) |
|Concussion (e.g., mild traumatic brain injury) || |
|Trigeminal neuralgia || || |
|Medication overuse headache|| || |
- Trigeminal autonomic cephalalgias: , paroxysmal hemicrania
- Other primary headaches: cough headaches, headaches due to physical exertion, postcoital headache
- Intracerebral hemorrhage
- Increased intracranial pressure
- Decreased intracranial pressure (e.g., post-lumbar puncture headache)
- Brain tumors
- Hypoxia and/or hypercapnia (e.g., high-altitude headache)
- Refractive errors
- Post-ictal headache
- Cervicogenic headache (e.g., cervical disc disease)
- Temporomandibular joint disorders
- Post-herpetic neuralgia
- Optic neuritis
The differential diagnoses listed here are not exhaustive.