2021 Volume 38 Issue 4 Pages 627-631
Trigeminal autonomic cephalalgias (TACs) is a concept introduced in the 2nd edition of the International Headache Classification, and has since been continued in the 3rd edition. Types of headaches in TACs include cluster headache, paroxysmal hemicrania, short–lasting unilateral neuralgiform headache attacks, hemicrania continua, and probable trigeminal autonomic cephalalgia.
Headaches classified as TACs share the clinical features of unilateral headache and, usually, prominent cranial parasympathetic autonomic features, such as 1) conjunctival injection and/or lacrimation, 2) nasal congestion and/or rhinorrhea, 3) eyelid oedema, 4) forehead and facial sweating, 5) miosis and/or ptosis, which are lateralized and ipsilateral to the headache.
Currently, the pathophysiology of TACs is suggested that activation of the hypothalamus, activation of the trigeminal–autonomic nerve reflex, internal carotid artery dilation, and some neuropeptides are involved in, but it is not unequivocal. There are many points for further studies are awaited.
