Headache

Definition

Headache is a common neurological symptom characterized by pain in the head or upper neck, which may arise from primary headache disorders or secondary causes such as systemic or intracranial disease.

Epidemiology

• Affects nearly 50–75% of adults globally at some point in life.
• Primary headaches (migraine, tension-type) are more common in women; cluster headaches more common in men.
• Migraine prevalence peaks in the 25–55-year age group.
• Tension-type headache is the most common worldwide.
• Headaches account for significant healthcare burden and lost productivity.

Etiology

• Primary headaches: migraine, tension-type, cluster, trigeminal autonomic cephalalgias.
• Secondary headaches: infection (meningitis, sinusitis), vascular disorders (stroke, hemorrhage), trauma, intracranial mass, systemic disease (hypertension, metabolic disorders).
• Triggers: stress, sleep disturbances, hormonal changes, dehydration, certain foods, medications.
• Genetic predisposition: strong familial link for migraine and cluster headaches.
• Lifestyle factors: caffeine withdrawal, alcohol, poor posture.

Pathophysiology

• Migraine: trigeminovascular activation, cortical spreading depression, and altered neurotransmitters (serotonin, CGRP).
• Tension-type: increased pericranial muscle tension, central pain sensitization.
• Cluster headache: hypothalamic dysfunction, trigeminal-autonomic activation.
• Secondary headache: local or systemic pathology causing nociceptive stimulation of pain-sensitive structures (meninges, vessels, sinuses).
• Inflammatory mediators and neurovascular dysfunction play a role in primary headaches.