What is a Headache?
A headache is a pain or discomfort in the head, scalp, or neck that can be characterized by its location, duration, intensity, quality, and associated symptoms, representing one of the most common neurological conditions worldwide. 1
Definition and Classification
Headaches are broadly categorized into two main types:
Primary Headache Disorders: Headaches that are not related to an underlying medical condition 2
- Migraine
- Tension-type headache
- Trigeminal autonomic cephalalgias
- Other primary headache disorders
Secondary Headache Disorders: Headaches that are due to an underlying medical condition 2
- Vascular causes
- Neoplastic causes
- Infectious causes
- Intracranial pressure/volume causes
Clinical Characteristics of Common Headache Types
Migraine Headache
According to the International Headache Society classification 1, migraine is characterized by:
- Recurrent attacks lasting 4-72 hours
- Typically unilateral location
- Pulsating quality
- Moderate to severe intensity
- Aggravation by routine physical activity
- Associated with nausea/vomiting and/or photophobia and phonophobia
Tension-Type Headache
The International Headache Society defines tension-type headache as having 3:
- Pressing or tightening (non-pulsatile) quality
- Mild to moderate intensity
- Bilateral location
- No aggravation with routine activity
- No nausea or vomiting (may have anorexia)
- No photophobia and phonophobia (or only one of these)
Cluster Headache
Characterized by 3:
- Severe unilateral pain (orbital, supraorbital, temporal)
- Duration of 15-180 minutes untreated
- Accompanied by ipsilateral autonomic symptoms (lacrimation, nasal congestion, rhinorrhea, sweating, ptosis, miosis, eyelid edema)
Pathophysiology
Headaches involve complex neurological mechanisms:
Migraine: Involves activation of the trigeminovascular system, release of inflammatory neuropeptides like calcitonin gene-related peptide (CGRP), and cortical spreading depression 3, 2
Tension-type headache: May involve peripheral pain mechanisms (myofascial pain) and central sensitization of pain pathways 4
Red Flag Symptoms
Certain headache characteristics warrant immediate medical attention 1:
- Thunderclap headache (sudden, severe headache reaching maximum intensity within seconds to minutes)
- Focal neurological deficits
- Altered mental status
- Neck stiffness
- Headache following trauma
- New-onset headache in patients over 50
- Headache in immunocompromised patients or those with cancer
Diagnostic Approach
Accurate diagnosis involves:
- Detailed assessment of headache location, duration, and triggers
- Evaluation of associated symptoms
- Identification of relieving factors
- Assessment of comorbid conditions
- Family history
- Occupational factors and sleep patterns 1
Using headache diaries can help track patterns and frequency, which is crucial for accurate diagnosis and management 1.
Impact and Epidemiology
- Approximately 90% of people experience headache during their lifetime 2
- Tension-type headache affects about 38% of the population 2
- Migraine affects approximately 12% of the population and is the second leading cause of years lived with disability worldwide 2
- Headache disorders have significant socioeconomic impact through both direct medical costs and indirect costs from lost productivity 3
Understanding what a headache is requires recognizing it as a complex neurological phenomenon with various presentations, causes, and mechanisms rather than simply a symptom of pain in the head.