Pain Relief in Short-Lasting Unilateral Neuralgiform Headache with Conjunctival inJection and Tearing Syndrome with Intravenous Ketamine: A Case Report.

Purpose: Short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT) is a rare form of primary headache, classified as trigeminal autonomic cephalalgia. Since the underlying mechanism of the pathogenesis has not yet been determined, a standardized therapeutic strategy for SUNCT is unavailable. We present a case of SUNCT syndrome with successful pain relief by intravenous administration of ketamine, an N-methyl-D-aspartate receptor (NMDAR) antagonist.

Case report: A 56-year-old male patient reported severe throbbing and shooting pain in forehead, temporal and periorbital region. We confirmed conjunctival injection, lacrimation, blepharoptosis, and miosis as symptoms related to autonomic activity, and made a diagnosis of SUNCT based on ICHD-3 beta. Numerous treatments were attempted, including pregabalin, gabapentine, nonsteroidal antiinflammatory drugs, acetaminophen, steroids, antidepressants, triptans, nerve blocks, and intravenous lidocaine with unsatisfactory results. Intravenous administration of ketamine (0.4 mg/kg) for one hour, was found to relieve the severe pain.

Conclusion: Intravenous ketamine can effectively treat SUNCT syndrome. This case demonstrated that involvement of NMDAR could be one of the mechanisms of SUNCT syndrome pathogenesis and establish a therapeutic strategy for this pain syndrome.