The causes of neuralgias are varied.Chemicals can cause nerve irritation. Inflammation, trauma (including surgery),compression by adjacent structures (tumors or inflamed tissues), and infectionscan all lead to neuralgias. In many cases, however, the cause is unknown orunidentifiable.Neuralgias are most common in elderly persons, but they can occurat any age.Trigeminal neuralgia is the most common form of neuralgia. It affects the mainsensory nerve of the face, the trigeminal nerve ("trigeminal"literally means "three origins", referring to the division of thenerve into three branches). This condition involves sudden and short attacks ofsevere pain on one side of the face, along one of the areas supplied by thetrigeminal nerve. The pain attacks may be severe enough to cause a facialgrimace, which is classically referred to as a painful tic (tic douloureux). Thecause of trigeminal neuralgia is occasionally a blood vessel or small tumorpressing on the nerve. Disorders such as multiple sclerosis (an inflammatorydisease affecting the brain and spinal cord), certain forms of arthritis, anddiabetes (high blood sugar) can also cause trigeminal neuralgia, but mostcommonly a cause is not identified. In this condition, certain movements such aschewing, talking, swallowing, or touching an area of the face may trigger aspasm of excruciating pain.
 

Trigeminal neuralgia tends to come andgo, but successive attacks may be disabling. Although neuralgia is not fatal,the patient's fear of being in pain can seriously interfere with daily life. Somepeople with postherpetic neuralgia respond completely to treatment. Most people,however, experience some pain after treatment, and a few receive no relief atall. Some people live with this type of neuralgia for the rest of their lives,but for most, the condition gradually fades away within five years.