see also:

• acute unilateral headache

• recurrent clusters of sudden onset lancinating retro-orbital headaches lasting minutes to 3 hours usually occurring in the early hours of the morning (perhaps REM sleep mediated) causing the patient to become agitated, restless and walk around
• historically mainly adult males who smoke heavily and have high alcohol intake but becoming more widely recognised in women as well with gender ratio now around 2:1 rather than historic 6:1 ratio
• usually associated with one or more features of ipsilateral Horner's syndrome
• usually responds well to 100% oxygen

• 100% oxygen
• triptans
• sphenopalatine ganglion stimulation where available
• probably effective Rx:
  • civamide nasal spray
• possibly effective:
  • lithium, verapamil, warfarin and melatonin ¹⁾

• suboccipital steroid injections
• ? role of calcium channel blockers in prevention