Funct Neurol
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In the indomethacin responsive headaches (IRHs), chronic paroxysmal hemicrania (CPH) and Hemicrania continua (HC), the indomethacin (INDO) response is swift, absolute, and permanent, with moderate doses. Traditionally, CPH has been linked to cluster headache (CH) due to clinical similarities: unilaterality, intensity, and some autonomic phenomena. However, other clinical features differ essentially between these two headaches: sex ratio, mean attack frequency (CPH: 13.6 versus CH: 1.7 attacks/day), and duration of attacks. ⋯ The chronic/non-chronic stage ratio is 3.9 in CPH, against 0.14 in CH, a >25 times difference. Conversely, CPH and HC are very similar, clinically speaking. Accordingly, we should probably sever the link between CH and CPH and favour, instead, a linking together of CPH and HC, the two principal IRHs.