Lynn Poole shows an artist's rendition of tic douloureux or trigeminal neuralgia, and Dr. Smith describes this pain of the fifth cranial nerve. A sketch of the head shows the three nerve divisions in the face, and an electrical model traces the nerve's pain transmittal to the brain. The causes of this affliction are unknown and the occurrences unpredictable although the painful attacks often occur from eating, talking, or touching the face. This is a disease of advancing years, and Dr. Smith interviews an elderly patient, Mrs. White, who attempts to describe her symptoms until orifacial pain overcomes her. As early as the 1500s treatments included surgery to cut the nerve. This is still performed, and Dr. Smith interviews Mrs. Frank, who received such surgery and now has no sensation of pain at all in one side of her face, as evidenced by the doctor sticking a pin into her cheek. Other remedies now include chemically damaging the nerve by injecting it with alcohol or novocaine, cutting the fiber track.