The attacks in SUNCT syndrome are strictly unilateral, generally with the pain persistently confined to the ocular/periocular area. Most attacks are moderate to severe in intensity and burning, stabbing or electrical in character. The mean duration of paroxysms is 1 minute, with a usual range of 10 to 120 seconds (total range 5 to 250 seconds). Prominent, ipsilateral conjunctival injection and lacrimation regularly accompany the attacks. Nasal stuffiness/rhinorrhoea is frequently noted. In addition, there is a subclinical forehead sweating. During attacks, there is increased intraocular pressure on the symptomatic side and swelling of the eyelids. No changes in pupil diameter have been observed. Attacks can be triggered mostly from trigeminally innervated areas, but also from the extratrigeminal territory. There are also spontaneous attacks. An irregular temporal pattern is a rule, with symptomatic periods alternating with remissions in an unpredictable fashion. During active periods, the frequency of attacks may vary from <1 attack/day to >30 attacks/hour. The attacks predominate during the daytime, nocturnal attacks being seldom reported.