Trigeminal neuralgia is the term used to describe pain related to the trigeminal nerve or one of its branches. The trigeminal nerve transmits impulses from the nerves in your face to your brain. Trigeminal neuralgia is a chronic pain condition that affects this nerve causing even slight stimulation to the face to trigger unbearable pain. The exact source of trigeminal neuralgia is unclear. In some cases physicians may be able to determine cause from injury or damage to the nerves, or from centrally located changes in the brain, such as a migraine headache.