Q My sister may have trigeminal neuralgia. What causes this?

ATrigeminal neuralgia (TGN) is an extremely unpleasant facial pain, caused by pressure on the trigeminal nerve inside the brain (usually by a blood vessel, but occasionally by tumours, multiple sclerosis and other conditions). It affects around one in 4,000 people a year, often in late middle-age, and is more common in women.

Each trigeminal nerve relays sensations from one side of the face to the brain, and sends instructions to the muscles that control chewing. TGN produces abnormal signals – frequent bouts of ‘electric shock’-type pains that last seconds or minutes. They can be triggered by touch, eating or even the wind.

Facial pain has many causes, so your sister may need a dental check, blood tests and X-rays. An MRI scan can identify other conditions as well as nerve damage.

TGN can be treated with drugs that block nerve signals, such as some used for epilepsy or depression, although they may take time to work. It may disappear by itself after weeks or months, but can reappear. In severe cases, surgery to relieve the pressure or stop the nerve working can help.