TABLE 1.

Effects of electrical stimulation of the trigeminal nerve on cerebral blood flow.

Stimulation target	Stimulation method	Study group	Stimulation parameters					Result of stimulation on CBF		Adverse events	Study
			Frequency	Pulse amplitude	Pulse width	Waveform	Burst width	Observation	Location
Opthalmic division	Minimally invasive EA, supraorbital nerve	Awake, resting humans	100 Hz		0.25 ms		1 min	↑ CBF	Prefrontal cortex	No adverse events occurred	Suzuki et al., 2020
	Invasive, right nasociliary nerve	Anesthetized rats	3, 10, 30, and 60 Hz	5 V	0.5 ms	Square Monophasic	90 s	↑ CBF w/↑ frequency	Ipsilateral parietal cortex	No adverse events reported	Suzuki et al., 1990
	Invasive, nasociliary nerve	Anesthetized, paralyzed cats	0.5, 1.5, 10, and 20/s	100 uA	0.25 ms	Square		↑ CBF	Posterior parietal cortex	No adverse events reported	Edvinsson et al., 1998
	Non-invasive, transcorneal, nasociliary nerve	Anesthetized rats with SAH	30 Hz	3 mA	1 ms	Biphasic	30 s	↑ CBF ↓ CVR w/and w/out SAH	Middle cerebral artery	No adverse events reported	Atalay et al., 2002
	Non-invasive, nasociliary nerve	Anesthetized rabbits	10 Hz	1, 2, 3, 4, and 5 V	0.5 ms	Square	90 s	↑ CBF as a function of voltage (1–5 V)	Premotor cortex	No adverse events reported	Gürelik et al., 2004
	Subcutaneous	Anesthetized rats with MCAO	25 Hz	60 μA	0.5 ms	Rectangular Cathodal	75 min	Not stated for electrical	Parietal cortex	No adverse events reported	Shiflett et al., 2015
	Invasive and subcutaneous Intermittent	Anesthetized rats with TBI	25 and 100 Hz	1–3 V	0.5 ms	Rectangular Biphasic	1 min	↑ CBF and ↓CVR w/and w/out TBI	Ipsilateral cortex	No adverse events reported	Chiluwal et al., 2017
Maxillary division	Percutaneous, infraorbital nerve	Anesthetized rats	2 Hz	1.2 mA	1 ms		210 s	↑ CBF	Barrel cortex	No adverse events reported	Weber et al., 2003
	Percutaneous, infraorbital nerve	Anesthetized rats	0.25, 0.5, 1.0, 2.0, 3.0, 5, 8, 10, and 12 Hz	2 mA 1–6 mA (1 Hz)	0.1 ms	Square	60 s	↑ CBF as a function of frequency, up to 3 Hz	Barrel cortex	No adverse events reported	Just et al., 2010
	Percutaneous, infraorbital nerve	Anesthetized rats with HS	25 Hz	7 V	0.5 ms	Rectangular Biphasic	1 min	↑ CBF after hemorrhagic shock	ML: +2 mm; AP: −2 mm	No adverse events reported	Li et al., 2019
	Percutaneous, infraorbital nerve	Anesthetized rats	50 and 133 Hz	0.25–3 V	1 ms	Rectangular Biphasic	1 min	↑ CBF ↓ CVR ↑ CGRP	ML: +2 mm; AP: −1 mm	No adverse events reported	Li et al., 2021
Mandibular division	Invasive, cut end of lingual nerve	Anesthetized rats	1–30 Hz	1–30 V	2 ms		20 s	No effect	Parietal cortex	No adverse events reported	Ishii et al., 2014
	Invasive, cut end of lingual nerve	Anesthetized cats	10 Hz	5–40 V	2 ms		20 s	No effect on CBF	Frontal cerebral cortex		Sato et al., 1997
Ganglion	Invasive	Anesthetized cats	10/s	500 uA	0.25 ms	Square		↑ CBF	Frontal and parietal cortex	No adverse events reported	Goadsby and Duckworth, 1987
	Invasive	Anesthetized cats	0.5, 1, 2, 5, 10, and 20/s	250 uA	0.25 ms	Square	30 s	↓ CVR	Parietal cortex	No adverse events reported	Goadsby et al., 1997
	Invasive, distal end	Isolated canine brains attached to anesthetized canines	50 Hz	10 V	1 ms	Rectangular Square	20 ms	↑ CBF ↓ CVR	Global	No adverse events reported	Lang and Zimmer, 1974
	Invasive	Anesthetized pigs	45/s	2.5 V 75 A	0.2 ms		3 h	↑ CBF w/and w/out SAH	Global	No adverse events reported	Salar et al., 1992