Restored brain perfusion after non-invasive stimulation of the facial nerve in a canine stroke model

Ischemic stroke affects over 15 million patients per year and is a leading cause of death worldwide. Currently available treatments are indicated for less than 5% of patients. Stimulation of the facial nerve has been proposed as a possible new treatment of ischemic stroke that acts by increasing blood flow to the brain and thereby restoring perfusion through collateral vessels. The objective of this project was to evaluate the changes in brain perfusion, following facial nerve stimulation in an animal stroke model using MRI measures of cerebral blood flow. Autologous blood clot was injected in the internal carotid artery to occlude the middle cerebral artery (MCA) in 17 mongrel dogs. Occlusion in the MCA was verified using fluoroscopy and MRI angiography. Following baseline and post-stroke MRI images, the facial nerve at the site of the geniculate ganglion was located and then stimulated using a transcranial magnetic stimulator and a neuro-navigation system in 11 animals. Six animals followed the same procedure but were not stimulated (control group). The perfusion index of both sides of the brain was measured using gadolinium contrast MRI before and after stroke, and at 30 minute intervals after stimulation. Results show a significant and persistent increase in perfusion in the stroke side of the brain relative to the non-stroke / contralateral side, after stimulation, when compared to the control group. These results strongly support the future development and evaluation of a non-invasive facial nerve stimulator device for the early treatment of ischemic stroke.