Short-lasting, Unilateral, Neuralgiform headache attacks with Conjunctival injection and Tearing (SUNCT) is a very rare type of headache with bursts of moderate to severe burning, piercing, or throbbing pain that is usually felt in the forehead, eye, or temple on one side of the head. The pain usually peaks within seconds of onset and may follow a pattern of increasing and decreasing intensity. Attacks typically occur during the day and last from 5 seconds to 4 minutes per episode. Individuals generally have five to six attacks per hour and are pain-free between attacks. This primary headache is slightly more common in men than in women, with onset usually after age 50. SUNCT may be episodic, occurring once or twice annually with headaches that remit and recur, or chronic, lasting more than a year.
The symptoms of SUNCT include reddish or bloodshot eyes (conjunctival injection), watery eyes, stuffy or runny nose, sweaty forehead, puffy eyelids, increased pressure within the eye on the affected side of the head, and increased blood pressure.
SUNCT is very difficult to treat. Anticonvulsants may relieve some of the symptoms, while anesthetics and corticosteroid drugs can treat some of the severe pain felt during these headaches. Surgery and glycerol injections to block nerve signaling along the trigeminal nerve have poor outcomes and provide only temporary relief in severe cases. Doctors are beginning to use deep brain stimulation (involving a surgically implanted battery-powered electrode that emits pulses of energy to surrounding brain tissue) to reduce the frequency of attacks in severely affected individuals.
This answer is based on source information from the National Institute of Neurological Disorders and Stroke.