SUNCT Syndrome (Trigeminal Autonomic Cephalalgia)

Short-lasting Unilateral Neuralgiform headache attacks with Conjunctival injection and Tearing (SUNCT) is part of the trigeminal autonomic cephalalgias (TACs), alongside cluster headache, paroxysmal hemicrania, and SUNA. Attacks are unilateral, peri-orbital or temporal, lasting 5 to 240 seconds, occurring 3 to 200 times daily, with prominent ipsilateral autonomic features (conjunctival injection, tearing, rhinorrhea, ptosis).

Pathophysiology involves trigeminal-parasympathetic reflex activation, often with hypothalamic dysfunction shown on functional imaging. Secondary SUNCT may be triggered by posterior fossa lesions, pituitary tumors, vascular anomalies, and trigeminal nerve compression. Attacks are precipitated by cutaneous trigger zones and refractory periods that distinguish SUNCT from trigeminal neuralgia.

Diagnosis is clinical (ICHD-3) supported by brain and pituitary MRI to exclude secondary causes. Acute treatment is limited because attacks are too brief; intravenous lidocaine can abort severe clusters. Preventive therapy uses lamotrigine first-line, with topiramate, gabapentin, oxcarbazepine, and verapamil as alternatives. Refractory cases may benefit from greater occipital nerve block, microvascular decompression of the trigeminal nerve, or hypothalamic deep brain stimulation.