Types of Headache Based on Harrison's Classification
Primary Headache Disorders
Headaches are fundamentally divided into primary headache disorders (which have no underlying pathologic cause) and secondary headache disorders (which result from underlying medical conditions). 1 The three main primary headache types are migraine, tension-type headache, and cluster headache. 1
Migraine
- Unilateral, pulsatile pain of moderate to severe intensity that worsens with routine physical activity 1, 2
- Must have at least two of the following characteristics: unilateral location, throbbing character, worsening with routine activity, or moderate to severe intensity 1
- Associated symptoms include nausea/vomiting and/or photophobia with phonophobia 1, 2
- Can occur with or without aura (visual distortions, scotomas, or other neurologic symptoms preceding the headache) 1
- Affects 18% of women and 6.5% of men in the United States 1
- Duration typically 4-72 hours when untreated 3
Tension-Type Headache
- Bilateral, pressing or tightening quality (non-pulsatile) of mild to moderate intensity 1, 4
- Not aggravated by routine physical activity, which distinguishes it from migraine 1, 4
- Must have at least two of the following: pressing/tightening character, mild to moderate intensity, bilateral location, or no aggravation with routine activity 1
- Lacks prominent associated symptoms: no nausea/vomiting (though anorexia may occur) and typically does not have both photophobia and phonophobia 1, 4
- Most prevalent primary headache, affecting 38% of the population 3
Cluster Headache and Trigeminal Autonomic Cephalalgias
- Strictly unilateral, severe to very severe pain lasting 15-180 minutes 1, 5
- Requires five attacks with frequency of 1-8 attacks per day 1, 5
- Ipsilateral cranial autonomic symptoms are mandatory: lacrimation, conjunctival injection, nasal congestion, rhinorrhea, forehead/facial sweating, ptosis, miosis, or eyelid edema 1, 5
- Much less prevalent, affecting only ~0.1% of the general population 1
- Attacks are short-lasting but frequently recurrent 1
Secondary Headache Disorders
Secondary headaches result from underlying pathologic causes and are far less common than primary headaches. 1 These include headaches attributed to: 1
- Head and/or neck trauma 1
- Cranial or cervical vascular disorders 1
- Nonvascular intracranial disorders (tumors, increased intracranial pressure) 1
- Substance use or withdrawal 1
- Infection (meningitis, encephalitis) 1
- Disorders of homeostasis 1
Critical Red Flags Requiring Investigation
Neuroimaging or further testing is indicated only when red flags suggest secondary causes: 1
- Thunderclap headache (abrupt onset of severe headache) 1, 6
- Focal neurologic signs or symptoms 1, 6
- Unexplained fever 1
- Rapidly increasing headache frequency 1
- Headache awakening patient from sleep 1
- Age ≥50 years at onset 3, 6
- History of cancer or immunosuppression 3, 6
- Head trauma 1, 6
- Papilledema 6
- Neck stiffness 6
Diagnostic Approach
A single patient can have more than one type of headache disorder simultaneously—for example, migraine patients commonly also experience episodic tension-type headaches. 1 The International Headache Society classification system diagnoses headache syndromes, not patients. 1
Validated Screening Tools
- ID-Migraine questionnaire (3 items): sensitivity 0.81, specificity 0.75, positive predictive value 0.93 1
- Migraine Screen Questionnaire (MS-Q) (5 items): sensitivity 0.93, specificity 0.81, positive predictive value 0.83 1
- Headache diaries to track frequency, intensity, and associated symptoms 1, 2
Neuroimaging Indications
Routine neuroimaging is NOT indicated for typical primary headaches without red flags. 1, 2, 4 When needed, MRI is preferred over CT as it offers higher resolution without ionizing radiation. 1 CT is reserved primarily for suspected acute hemorrhage or trauma. 6, 7