An attack may last 30 minutes to 4 hours, several times a day over a 6-8 week period. Cluster Headache may be precipitated by trauma. This syndrome usually involves middle aged or elderly males, and there is a severe unilateral headache in the distribution of the 5th cranial nerve. If there is only the unilateral pain and a Horner's syndrome, this may represent a cluster headache. Symptoms resolve over weeks to months.
Similar symptoms can arise from carotid artery dissection and fibromuscular dysplasia.
Consider imaging studies such as MRI, MRA, or even arteriography to rule-out structural lesions or vascular lesions in cases of Cluster Headache. The sympathetic nerve fibers serving the face, eye, and eyelids originate in the hypothalamus and travel to the C8 - T2 level of the spinal cord. These fibers terminate in the superior cervical ganglion. These sympathetic fibers allow pupil dilation and cause and eyelid opening of about 2-3 mm. Sympathetic fibers to the face travel with the external carotid artery.