Trigeminal neuralgia (TN) is an uncommon condition characterized by intense recurrent attacks of piercing facial or jaw pain. The disorder was first described back in the Roman times. The nerve most affected is a cranial nerve called the Trigeminal Nerve. This nerve has three branches: 1) ophthalmic branch which innervates the area of the forehead and the eye, 2) maxillary branch which innervates the area around the nose, cheek and upper lip, and 3) mandibular branch which innervates the area around the jaw. The attacks may involve any one of the branches or all 3 branches at once. The maxillary branch is the most commonly affected. The right side is the more commonly affected than the left side. Trigeminal neuralgia affects about 4.5 people out of every 100,000 population. There is a slight female predominance. TN is unusual under the age of 40 years old with a peak incidence between the ages of 60-70 years of age. There does not appear to be a racial predilection.
The exact cause of TN is unknown but current theories believe that the superior cerebellar artery may cause compression of the nerve root. This compression of the nerve root causes a loss of the myelin insulation between the nerve fibers within the nerve bundle. This would be similar to all the insulation coming off the individual phone lines in the phone cable. The results of this would be chaos for the phone systems served by this phone cable. When the nerve becomes dysfunctional intense episodic pain appears to be the results.
The diagnosis of TN is difficult since there is no specific test for the condition. The history usually includes paroxysmal episodic attacks lasting 1 second to 2 minutes. They must occur in the trigeminal nerve distribution. They are usually intense stabbing or sharp pains. Sometimes specific triggers such as smiling, chewing, brushing teeth or talking can set off an episode. The history is important to rule out other causes of facial pain. TN is almost never associated with vertigo, vision changes, or hearing loss. TN is almost always on one side. The physical exam is usually normal since the patient is almost always asymptomatic when seeing the physician. Tests like MRI are not very useful in diagnosing TN.
Treatment maybe medical or surgical. Medical treatment usually involves carbamazepine, an antiseizure medication. If carbamazepine fails or the patient is intolerant to this medication, other anti seizure medications have been found to be effective. Some of include gabapentin, Lamictal, Depakote, and Topamax. More recently Botox injections have been shown to help control TN. Topical Zostrix and transcutaneous nerve stimulation (TENS) are two treatments being tested for the treatment of TN. Treatments to decompress the nerve root include a gamma knife (a form of radiation), radiofrequency ablation and balloon compression.
In summary, TN is a relatively uncommon neurological disorder, but due to its intense symptoms can be quite debilitating. It is due to the intensity of the pain that treatment is often required.
Mark Smith, MD