Bell's palsy involves a rapid start of partial or complete paralysis that often occurs overnight. Scientists believe that inflammation leads to swelling of the facial nerve. The nerve travels through the skull in a narrow bone canal beneath the ear. Nerve swelling and compression in the narrow bone canal are thought to stop the nerve from working. At times of lowered immunity, a dormant (sleeping) virus, usually the chicken pox or cold sore virus, can wake up and attack the nerve causing it to swell. The main symptoms of Bell's palsy are one-sided facial paralysis, jaw pain, dizziness, strengthened hearing in one ear, and weakened taste sense.