Ketamine + Magnesium for Chronic Cluster Headache (KETALGIA)

Randomised, double-blind, parallel-group trial comparing a single infusion of ketamine (0.5 mg/kg over 2 hours) plus magnesium sulfate (3 g over 30 minutes) versus an active comparator (hydroxyzine 25 mg) in patients with refractory chronic cluster headache.

Primary outcome compares mean daily attack frequency in the 14 days before infusion with days 7–8 after infusion; follow-up to 90 days to assess durability and safety.