Trigeminal neuralgia is one of the most painful conditions known to mankind. Its cause is unknown, but the current hypothesis, that it is due to microvascular compression of the trigeminal nerve adjacent to the brain-stem by blood vessels, has not been proved. Patients are usually over 40 years of age, unless the condition is associated with multiple sclerosis, and Africans are rarely affected. There is no diagnostic test: diagnosis depends on the clinical features.

The pain is usually stabbing in quality and in the distribution of the trigeminal nerve. It is almost always unilateral, and is precipitated by many factors, including touch, chewing, and talking. Remissions occur and may last for weeks, or even years; however the pain inevitably returns. If carbamazepine fails to produce clear relief then the diagnosis is in doubt. A few patients develop an idiosyncratic rash and are unable to take the drug.

The surgical treatment is debated. If carbamazepine fails to control the pain ‘numbing’ the trigeminal nerve is effective. This procedure can be performed anywhere in the distribution of the pain; in the skin, mucosa, peripheral nerve, nerve root, or brain-stem. Although most other pain-relieving operations depend on cutting the nerve fibres between the cause of the pain and the brain, this does not seem to be the case with trigeminal neuralgia. Rubbing the nerve will stop the pain in two-thirds of patients.

Glycerol injections, balloon compression, radiofrequency lesions, ‘microvascular decompression’, or partial sectioning (Fig. 1) 2297 of the trigeminal sensory root in the posterior fossa have all been used: the less the root is damaged, the greater the recurrence rate. Although many patients want overwhelmingly to be rid of the pain permanently, care must be taken in counselling: a numb face is not normal, and the patient must understand fully the effect of any proposed procedure.

Glossopharyngeal neuralgia has similar features to trigeminal neuralgia, but occurs in the distribution of the glossopharyngeal nerve.

Adams CBT. Microvascular compression: an alternative view and hypothesis. J Neurosurg, 1989; 57: 1–12.

Gybels JM, Sweet WH. Neurosurgical treatment of Persistent Pain. Basel: Karger, 1989.