Trigeminal autonomic cephalalgias characterized by similar structural differences in the anterior hypothalamus

Introduction Trigeminal autonomic cephalalgias (TACs) are characterized by frequent, severe, unilateral headaches accompanied by ipsilateral cranial autonomic symptoms. Subdivision in cluster headache (CH), paroxysmal hemicrania (PH) and short-lasting neuralgiform headache with conjunctival injection and tearing (SUNCT) is mainly based on duration and frequency of attacks [1]. In the TAC pathophysiology, the hypothalamus seems to play a major role. The volume of posterior inferior hypothalamic gray matter (GM) was reported to be increased in CH patients [2], a finding that coinitiated the incidental application of (risky) deep brain stimulation (DBS) to this area to alleviate pain in chronic intractable CH, PH and SUNCT. However, the results of this single VBM study in CH have not been reproduced so far, and it is unknown if similar structural differences are also present in the other types of TACs, and whether they are specific for TACs (e.g. do not occur in migraine).