Functional Disease – Trigeminal Neuralgia
Trigeminal neuralgia (TN) or facial pain (also called “tic doloreux”) is manifested as acute attacks of pain in the face. The pain occurs in the area supplied by the fifth cranial nerve (the trigeminal nerve), and affects one side of the face only. The attacks are typically triggered by light touch, speaking, eating, brushing the teeth or moving from a warm environment to a cold one. Some patients have not only these acute attacks but also continual facial pain.
There are three causes of TN. The pain stimulus is frequently caused in the nerves by the pressure of a blood vessel lying on the nerve.
In rare cases the symptoms are caused by compression of the trigeminal nerve by a tumour. This is called secondary TN. As a rule such tumours are benign.
In most cases the cause is not known, and this is called idiopathic TN.
Whatever the cause, TN can almost always be controlled well with antiepileptic drugs such as carbamazepine. If drug treatment causes serious side-effects, or if the effect is no longer sufficient, the patient may undergo surgery. In addition to thermocoagulation of the trigeminal ganglion (gasserian ganglion), the options include the Janetta operation (in which pads are placed around the blood vessel that is compressing the nerve). For several years now, radiosurgery with the Gamma Knife has also been used to treat trigeminal neuralgia and has shown good results.
In about 80% of cases, local irradiation of the trigeminal nerve close to the brain stem relieves the patient’s pain either totally or to a considerable degree. The onset of the effect is generally several weeks or months after treatment. In 10% of these patients the pain returns within a year. Around 5% of patients experience side-effects in the form of numbness or reduced lacrimal flow.
