Atypical trigeminal neuralgia (ATN), otherwise known as type 2 trigeminal neuralgia, is a rare form of trigeminal neuralgia. Around 4-5 people per 100,000 have trigeminal neuralgia and a small subset of those have ATN.
It is a disorder of the fifth cranial nerve (trigeminal nerve), where the nerve becomes inflamed and/or demyelinates.
What are the Symptoms of ATN?
ATN is less painful than its more common counterpart, trigeminal neuralgia, but the pain is more constant. Patients may experience a persistent headache that lasts for days at a time and keeps re-occurring. This may be mistaken for a migraine. They will have pain in the trigeminal nerve, sometimes in all of the nerve branches and may have pain around their ears, jaws, nose, eyes and scalp. Pain can be felt as a mild ache, a crushing pressure sensation or a sharp stabbing sensation.
Unlike ordinary trigeminal neuralgia, the atypical type affects people of all ages. Trigeminal neuralgia is more common in those over 40.
What Causes ATN?
ATN can be caused by vascular compression and this is the most common cause of the disease. If the pain is constant, rather than coming and going, it may be a sign of a tumor compressing the nerve, in which case further investigations need to be carried out. If the pain is intermittent, this is not the case.
It can also be caused by trauma, either by an accident or more commonly, a surgical procedure. It can occur after dental surgery. Sometimes it occurs as part of the aging process.
If an infection or long-term inflammatory condition has been present, this can, over time, damage the trigeminal nerve and result in ATN.
Medical Treatments for ATN
ATN is difficult to treat. The conventional medical treatments are either:
1. Use of high dose anti-inflammatory painkillers during a bout.
2. Use of anti-depressants or the anti-convulsant, Gabapentin, to shut down abnormal nerve function. It is thought after a long period of use that the nerve may regenerate normally. There is limited evidence that this type of treatment actually works, particularly for non-epileptic drugs.
3. Surgery. A glycerol injection can be given through the cheek and through the opening to the base of the skull where the three branches of the trigeminal nerve come together. The glycerol damages the insulation of trigeminal nerve fibers to stop pain sensations being transmitted. This is done under sedation.
4. Stereotactic Radiosurgery – this involves firing radiation beams at the trigeminal nerve. This causes a lesion to develop over the nerve (over a period of several months). This lesion stops the nerve from transmitting pain signals.
5. Microvascular Decompression – this is very invasive and involves the patient being put under general anesthetic. The surgeon then makes a small cut behind the ear, through which he puts a microscope. He then moves the vessels away from the nerve and places a cushion between the two. Although this is the most complicated of procedures, it is also the most effective.
Sources: Aust Fam Physician. 2005 Aug;34(8):641-5
Cochrane Database Syst Rev. 2006 Jul 19;3:CD004029
National Institute for Neurological Disorders and Stroke – Trigeminal Neuralgia Fact Sheet. http://www.ninds.nih.gov/disorders/trigeminal_neuralgia/detail_trigeminal_neuralgia.htm
http://facial-neuralgia.org/conditions/atfp.html
Patient UK - http://www.patient.co.uk/health/Trigeminal-Neuralgia.htm
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting, in addition to running a charity for people damaged by vaccines or medical mistakes.