Please remember that this is general information and is meant as a guide. All diagnoses and treatment options should be discussed in full with a qualified clinician.
Trigeminal neuralgia is a condition characterised by episodes of severe pain affecting the face, in the distribution of one or more branches of the trigeminal nerve. It tends to come in attacks, or paroxysms, and is often superimposed on a more constant ache. These attacks can last for days or even weeks and when they settle the patient can remain pain free for many months. A sensory trigger, such as chewing, speaking or touching the face in a specific place, can precipitate such attacks. It can also occur as a complication of multiple sclerosis. In many patients the cause is unknown but it is thought that compression of the nerve root or nerve root entry zone by tumours or blood vessels may be responsible.
There is a wide range of drugs available for the treatment of trigeminal pain, carbamazepine being most commonly used. Some patients are intolerant to drugs, or develop a requirement for increasing doses – eventually to the point of unacceptable toxicity - and therefore more radical treatment methods are called for.
Microvascular decompression involves manipulation of the blood vessels that are associated with the nerve root or nerve root entry zone. It is performed under general anaesthetic. This has had consistently good results, with approximately 80 per cent or more of patients being pain free afterwards. However, it has a recurrence rate, and although the complication rate is low, such complications when they do occur can be very serious.
Radiofrequency thermocoagulation is performed under general anaesthetic and produces a permanent lesion at the site of pain origin or trigger spot. This usually results in pain relief in the appropriate area. Results are generally good but complications, including deficits of other cranial nerves and facial numbness can occur.
Glycerol injections provide good pain relief with minimal sensory damage. Glycerol is injected directly into Meckel’s cave and locally damages the nerve. Pain control is generally good in the short term but can be limited and recurrence is relatively common.
Gamma knife is becoming increasingly popular for treating this condition. Treatment is delivered to a specific part of the nerve. A large dose can be delivered and tends to be well tolerated by the nerve, usually leaving it intact and fully functional. The complication rate is low but problems with later nerve function are sometimes seen. Successfully treated patients are usually pain free after about three weeks, although pain relief may occur sooner (or indeed later) after treatment. Long-term outcome studies are still needed but favourable results are beginning to emerge. Most patients have some response to treatment but total response rates are lower than for microvascular decompression. Approximately 55 per cent of patients might expect to be pain free, or have much reduced pain, after five years.