Fig. 1.

CH attack frequency (a), duration (b), and severity (c) with SoC alone and with SoC + nVNS. P values are from paired t tests. Patients who had 0 attacks while using nVNS therapy were excluded from analysis of attack duration and severity. Attack severity was rated on a 0 to 10 scale, with higher scores indicating greater severity. Abbreviations: CH, cluster headache; nVNS, non-invasive vagus nerve stimulation; SD, standard deviation; SoC, standard of care