Cluster headache (CH) is characterised by attacks of excruciating unilateral headache, ipsilateral cranial autonomic symptoms (CAS) and/or agitation. Nitroglycerin (NTG) is known to induce CH. This study is the first single-blind placebo-controlled study using intravenous NTG in CH to characterise comprehensively NTG induced CH attacks.Methods
CH patients attended three study visits in total, first visit CH patients were unblinded and received intravenous NTG 0.5mcg/kg/min over 20 minutes, if successful they were asked to return for blinded visits either receiving NTG or placebo. The clinical phenotype was recorded. The study was approved by the NHS Research Ethics Committee.Results
Thirty-three patients participated, 24 completed all study visits. Nineteen episodic cluster headache (58%) and 14 chronic cluster headache (42%). NTG brought on CH attacks (n= 26, 79%), agitation (n= 24, 73%) and CAS (n= 31, 94%) in the unblinded NTG visit. NTG brought on CH attacks (n= 19, 76%), agitation (n= 20, 80%) and CAS (n= 21, 84%) in the blinded NTG visit. Only one participant had a spontaneous CH attack (4%) in the placebo visits, four participants reported unilateral CAS symptoms, and none had agitation.Conclusion
We demonstrate that intravenous NTG effectively triggers CH attacks.