Facial nerve stimulation in healthy human subjects

Stroke affects more than 16 M people worldwide and emergency treatments are available for less than 5% of the patients. Magnetic stimulation of the facial nerve has been tested in pre-clinical studies as a new, non-invasive emergency treatment of ischemic stroke that acts by increasing cerebral blood flow (CBF). The objective of this study in healthy human subjects is to help understand the safety, tolerability, and effectiveness of a clinical prototype facial nerve stimulator as a first step toward clinical studies in ischemic stroke patients. The geniculate ganglion region of the facial nerve was located bilaterally with neuronavigation and then stimulated in 35 healthy subjects. Safety was assessed with adverse event reports and by medical examination in all 35 subjects. Tolerability was defined as each subjects' self-determined ability to withstand at least 2 minutes of stimulation at escalating power levels. MRI perfusion cerebral blood flow (CBF) measurements were available in 31 of the subjects. Stimulation produced a clear (> 25%) increase in CBF in 10 of 31 subjects, and smaller increases in most of the remaining subjects. These results support the development of our device as an emergency ischemic stroke treatment.