The pathophysiology of<unk>  is incompletely understood. Recent studies suggest the existence of a relationship between the hypothalamus and the condition.<unk> ional MRI and deep brain stimulation of a large patient pool showed activation of the posterior hypothalamus during attacks of primary<unk> , on both sides and contralaterally (on the opposite side).<unk> ional MRI studies suggest brain stem activation during attacks as well. Activation of the trigeminocervical complex and other related structures results from innervation from branches of trigeminal and upper cervical nerves. There exists a direct connection between trigeminal nucleus caudalis, which is located in the brain stem, and the posterior hypothalamus. Therefore, it is possible that stimulation of the peripheral trigeminal nerve activates the hypothalamus and the hypothalamus in turn communicates with the trigeminal nucleus caudalis via neurotransmitters such as orexin. Elevated levels of prolactin, secretion of which is regulated by the hypothalamus, seem to be associated with<unk>  attacks. Some patients with a pituitary tumor only experience attacks at night. These patients only exhibit higher levels of prolactin at night, even where hormone levels, including prolactin, were normal throughout the day.<unk>  is considered a primary headache (or condition), but can also occur as a secondary symptom of other conditions. However, a patient can only be diagnosed with<unk>  as a primary condition. A pituitary tumor causes<unk>  as a secondary headache. Some patients with a pituitary tumor complain of short-lasting heachaches. Upon removal of the tumor, the symptoms of<unk>  may disappear permanently. Although it occurs very rarely, paranasal sinusitis can also cause secondary<unk> . The symptoms of<unk>  in such cases can be removed permanently with endoscopic sinus surgery.
SUNCT syndrome
MASA syndrome
SAHA syndrome
Hopkins syndrome
TAN syndrome
EAST syndrome
Crome syndrome
Bogart–Bacall syndrome