The choice of acute therapy depends on patient factors and cost. Oxygen is contraindicated in active smokers and patients with type 2 respiratory failure. Triptans are contraindicated in patients with ischaemic heart disease.
Other abortive treatments that have some supporting evidence in cluster headache include non- invasive stimulation of the vagal nerve.23 Trials are investigating other forms of neuromodulation..
Bridging therapies
Despite a lack of supportive randomised data, prednisolone is commonly used as a bridging preventive strategy to allow the up-titration of safer long-term preventive therapies. A variety of prednisolone regimens have been successful in uncontrolled studies, however prolonged use should be minimised because of its adverse effects. Starting at 1 mg/kg (maximum dose 75 mg daily) with gastric ulcer prophylaxis, and down-titrating over two weeks, is one reasonable strategy.15,16
An alternative strategy is a greater occipital nerve block with an injection of local anaesthetic and depot- methylprednisolone. This combination can reduce attacks for on average four weeks and avoids the adverse effects of a course of oral steroids.24
Preventive therapy
Preventive therapy may be indicated long term in patients with chronic cluster headache, or seasonally, in patients with episodic cluster headache, depending on their history. Immediate-release or controlled- release verapamil is first line, and its use is supported by a randomised controlled trial, in which 80% of patients had a halving of attack frequency and 26% were attack free.25 Its efficacy is dose-dependent and the doses required for disease control can be in excess of the usual dose. Specialists can sometimes use up to 960 mg per day in divided doses (Table 2).5,15,16 Patients therefore require ECG monitoring before starting verapamil, during titration, and even after reaching a stable dose. One in five patients will develop an arrhythmia and delayed-onset arrhythmias have been reported.26,27 Arrhythmias include first-degree heart block, second-degree heart block, junctional rhythms, right bundle branch block and bradycardia.26 There is a need to check for drug interactions. Once a bout of cluster headache has finished, the patient can be weaned cautiously off verapamil, by 80 mg every one to two weeks.