3. Presence of any implanted electro-stimulating devices in the head and neck. 4. Presence of any large metallic craniofacial implants, such as bone fixation plates, mesh, et cetera. (Note that small metallic objects, such an aneurysm coils, are acceptable.) 5. Presence of an intracranial pressure monitor or any other similar sensor that may compromise the placement of the investigational device.