Trigeminal Autonomic Cephalalgias: Primary headache disorders that show symptoms caused by the activation of the AUTONOMIC NERVOUS SYSTEM of the TRIGEMINAL NERVE. These autonomic features include redness and tearing of the EYE, nasal congestion or discharge, facial SWEATING and other symptoms. Most subgroups show unilateral cranial PAIN.SUNCT Syndrome: A primary headache disorder that is characterized by frequent short-lasting, unilateral, neuralgiform pain attacks in the ocular area, with CONJUNCTIVA fluid-filling and tearing. SUNCT syndrome is usually resistant to treatment.Paroxysmal Hemicrania: A primary headache disorder that is similar to the CLUSTER HEADACHE with unilateral head pain, but differs by its multiple short severe attacks. It is usually seen in females, and may be responsive to non-steroidal-anti-inflammatory drugs (NSAIDS).Cluster Headache: A primary headache disorder that is characterized by severe, strictly unilateral PAIN which is orbital, supraorbital, temporal or in any combination of these sites, lasting 15-180 min. occurring 1 to 8 times a day. The attacks are associated with one or more of the following, all of which are ipsilateral: conjunctival injection, lacrimation, nasal congestion, rhinorrhea, facial SWEATING, eyelid EDEMA, and miosis. (International Classification of Headache Disorders, 2nd ed. Cephalalgia 2004: suppl 1)Headache: The symptom of PAIN in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of HEADACHE DISORDERS.Anisocoria: Unequal pupil size, which may represent a benign physiologic variant or a manifestation of disease. Pathologic anisocoria reflects an abnormality in the musculature of the iris (IRIS DISEASES) or in the parasympathetic or sympathetic pathways that innervate the pupil. Physiologic anisocoria refers to an asymmetry of pupil diameter, usually less than 2mm, that is not associated with disease.