Which medication is most appropriate for prophylaxis of cluster headaches?

• A. 100% oxygen via nasal cannula
• B. Amitriptyline
• C. Verapamil
• D. Dihydroergotamine mesylate

Answer: (C)

Prophylaxis of cluster headaches is best achieved with a calcium channel blocker because it effectively reduces both the frequency and severity of attacks in this condition. Verapamil helps dampen the abnormal rhythmic excitability of the trigeminal-vascular system that drives cluster headaches, leading to fewer attacks when given in a high-dose, gradually titrated regimen. Because these doses can affect the heart’s conduction system, it’s important to obtain baseline and ongoing ECG monitoring to watch for heart block or bradycardia.

Oxygen therapy, while highly effective for aborting an acute cluster attack, is not used to prevent future attacks. It serves as immediate relief during a headache, typically delivered at high flow with a suitable mask, not as a long-term preventive strategy.

Amitriptyline is useful for some migraine preventive regimens, but it does not have the same proven role in preventing cluster headaches. Dihydroergotamine is generally used for acute treatment in migraine contexts and is not a standard preventive therapy for cluster headaches, partly due to safety concerns with vasospasm and limited efficacy for prevention.

So, the best option for preventing cluster attacks is verapamil, with attention to cardiac monitoring due to the high-dose requirements.