SUNCT/SUNA are two variations of a rare type of headache called Short-lasting unilateral neuralgiform headache attacks. This type of headache is classified as a trigeminal autonomic cephalalgia (TAC). There are 4 types of TACs, and Short-lasting unilateral neuralgiform headache attacks (SUNCT/SUNA) are 1 of them. Short-lasting unilateral neuralgiform headache attacks (which include SUNCT and SUNA) are characterized by moderate to severe unilateral (one-sided) orbital (around the eye), supraorbital (above the eye), and/or temporal pain. The duration of the pain lasts for 1–600 seconds (1 second to 10 minutes, although most often about 5 seconds to 4 minutes), and may occur as single stabs, series of stabs, or in a sawtooth pattern. There must be at least 1 autonomic sign or symptom on the side of the headache [lacrimation (runniness/tearing of the eye), conjunctival injection (redness of the eye), facial sweating or flushing (skin turning blushed), nasal congestion, rhinorrhea (runniness of nose), sense of ear fullness, eyelid edema (swelling), or partial Horner’s syndrome (miosis (pupil becomes small)) and/or ptosis (droopiness of the eye)]. Attacks must have a frequency of at least one a day for more than half of the time when the disorder is active. However, the attacks generally occur in a very high daily frequency when active, sometimes even up to 200 attacks per day or 5-6 attacks per hour. SUNCT and SUNA both share the above criteria. The difference between the two is that SUNCT requires both conjunctival injection (redness of the eye) and lacrimation (runniness/tearing of the eye), whereas SUNA requires only 1 or neither of these 2 features.