Sensorimotor gating in chronic migraine and its association to bilateral greater occipital nerve block.

The effect of greater occipital nerve block (GONB) in migraine is based on the anatomic connections between the trigeminal nerve and upper cervical sensory fibers at the level of the trigeminal nucleus caudalis.1 The relationship between the trigeminal nerve and brainstem nuclei in the pathophysiology of migraine could be shown by recording the blink reflex (BR). Prepulse inhibition (PPI) of the BR is a decrease in BR excitability due to the conditioning stimulus and represents sensory gating at the brainstem.2 In the present study, we hypothesized that GONB would affect BR pathways in chronic migraine. For this purpose, we recorded BR, excitability recovery of BR, and PPI of BR before and after GONB in patients with chronic migraine. Thus, we were able to examine the sensory filtering at the brainstem. In a second step, we analyzed the electrophysiological findings in patients with the clinical response after GONB. All patients with chronic migraine3 referred for GONB between December 2018 and March 2020 were prospectively included. Patients with migraine who had comorbid disorders or allergies to local anesthetics or corticosteroids, patients who did not experience numbness after GONB, and patients who refused to participate were excluded. Healthy subjects without a history of headache were also enrolled.