What is Bell’s Palsy? Causes, Symptoms & Diagnosis Explained In this video, we discuss Bell’s Palsy—a condition that causes sudden weakness or paralysis on one side of the face. Learn about the possible causes, including viral infections like Herpes Simplex, Varicella Zoster, and Epstein-Barr virus, as well as risk factors such as stress, immune suppression, and sleep deprivation.