Table 2 Summary of features distinguishing the important primary headache disorders (NB: two or more of these disorders may occur concomitantly)

Temporal pattern

Episodic migraine:

 Recurrent attack-like episodes, lasting from 4 h to 3 days; frequency often 1–2/month but variable from 1/year to 2/week or more; freedom from symptoms between attacks

Chronic migraine:

 Episodicity lost: headache on ≥15 days/month, having migrainous features on ≥8 days/month

Frequent episodic TTH:

 Recurrent attack-like episodes lasting hours to a few days; 1–14 days affected per month; freedom from symptoms between attacks

Chronic TTH:

 ≥15 days affected per month (often daily and unremitting)

Episodic CH:

 Frequent (typically ≥1 daily) short-lasting attacks (15–180 min):

  • Recurring in bouts, usually once or sometimes twice a year, which are typically of 6–12 weeks’ duration;

  • Then remitting for ≥3 months

Chronic CH:

 Similar, but without such remissions between bouts

Typical headache characteristics

Often unilateral; often pulsating

Can be unilateral but more often generalised; may spread to the neck; typically described as pressure or tightness

Strictly unilateral (although side-shifts occur occasionally), around the eye or over the temple

Headache intensity

Typically moderate to severe

Typically mild to moderate

Extremely severe

Associated symptoms

Aura (in a minority of attacks); often nausea and/or vomiting; often photo- and/or phonophobia

Frequent episodic TTH:

 None typical; mild photophobia or phonophobia may occur

Chronic TTH:

 Sometimes mild nausea, but not vomiting

Strictly ipsilateral autonomic features:

 • Any or all of red and/or watering eye, running or blocked nostril, ptosis

Reactive behaviour

Avoidance of physical activity (maybe bed rest); preference for dark and quiet

None specific

Marked agitation: cannot lie still during attacks