Introduction

Paroxysmal hemicrania (PH) is a rare primary headache disorder characterised by recurrent attacks of severe, strictly unilateral pain, focused around the orbital, supraorbital and temporal regions and associated with autonomic features. Attacks usually occur more than five times a day and last 2–30 min.1 The disorder has an absolute response to indomethacin such that patients are rendered pain-free by therapeutic doses. Between 65% and 88% of patients suffer from the chronic form of PH where the attacks occur for more than 1 year without remission or with remission periods lasting less than 3 months.2 Over 30% of patients report dose-limiting side-effects with indomethacin and approximately 20% discontinue the drug due to tolerability problems.3 Although several other drugs have been reported to have efficacy in PH, none offer the same magnitude of response.

Evidence to support the role of the vagus nerve in trigeminal pain have been identified in prior studies. Inhibition of nociceptive activation of the trigeminocervical neurons have been shown in preclinical animal models, with a dose-dependent effect.4 Non-invasive vagus nerve stimulation (nVNS), using the gammaCore device, has been reported to be beneficial in trigeminal autonomic cephalalgias (TACs). A recent audit looking at 15 patients with indomethacin-responsive headaches, six of whom had PH, concluded that nVNS may be an important adjunct or alternative in those patients with …