External trigeminal nerve stimulation (eTNS) is an emerging noninvasive neuromodulation technique that modulates brain network activity implicated in multiple neuropsychiatric disorders through the application of low-intensity electrical currents to the frontal branches of the trigeminal nerve. Based on a search of major biomedical databases, we narratively synthesize clinical and mechanistic studies of eTNS across neurological and psychiatric indications. Current clinical and neurophysiological…
