The trigeminal autonomic cephalalgias (TACs) is a collective name for a group of primary headaches which present with pain on one side of the head in trigeminal nerve area and different “autonomic” features on the same side. "Autonomic" means changes in our body which are not under volitional control. They may include redness (conjunctival injection) or watering (lacrimation) of the eye, one-sided nasal congestion or discharge (rhinorrhea), forehead and facial sweating, constriction of a pupil (miosis), as well as drooping (ptosis) and swelling of an eyelid (eyelid edema).
Trigeminal autonomic cephalalgias include:
- Cluster headache
- Paroxysmal hemicrania
- Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT)
- Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA)
- Long-lasting autonomic symptoms with hemicrania (LASH)
Despite many resembling features, the TACs differ in attack duration and frequency:
- Cluster headache - lasts minutes to hours and frequency is up to 8 a day
- Paroxysmal hemicrania - lasts minutes and frequency is up to 40 a day
- SUNCT - lasts seconds to minutes and frequency is up to 200 a day
- LASH – lasts 1-3 days and frequency is up to 1 in 3 days
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