Noninvasive vagus nerve stimulation and the trigeminal autonomic reflex: An fMRI study.

Objective: The trigeminal autonomic reflex is a physiologic reflex that plays a crucial role in primary headache and particularly in trigeminal autonomic cephalalgias, such as cluster headache. Previous studies have shown that this reflex can be modulated by the vagus nerve, leading to an inhibition of the parasympathetic output of the reflex in healthy participants. The aim of the present study was to characterize neural correlates of the modulatory effect of noninvasive vagus nerve stimulation (nVNS) on the trigeminal autonomic reflex.

nVNS sham significantly affects the trigeminal-autonomic reflex: A randomized controlled study.

Objective: To determine whether high placebo effects observed in recently published clinical noninvasive vagal nerve stimulation (nVNS) trials can be attributed to an active modulation of the trigeminal-autonomic reflex by the sham device.

Methods: Twenty-eight healthy participants were investigated in a randomized, controlled, single-blind, within-participant design. The 4 different conditions of no stimulation, regular nVNS of the left cervical vagal nerve, stimulation of the posterior neck with the same device (sham I), and stimulation of the left cervical vagal nerve with a sham device (sham II) were applied in randomized order.

Vagus nerve stimulation modulates the cranial trigeminal autonomic reflex.

Objective: The trigeminal autonomic reflex plays an important role in primary headache syndromes. Noninvasive vagal nerve stimulation (nVNS) may be an effective modulator of this reflex.

Methods: Twenty-two healthy volunteers underwent kinetic oscillation stimulation (KOS) of the left nostril as a reliable trigger of the trigeminal autonomic reflex.