Trigeminal Neuralgia also known as tic douloureux involves a malfunction of the 5th cranial nerve or the trigeminal nerve. This nerve carries sensations from the face to the brain. Malfunctions of this nerve causes bouts of severe, piercing and burning pain. This pain can last seconds or minutes. Adults of any age can be affected, but it's usually the elderly. This is basically how the Merck Manuel decribes the disorder.
I've read that a true Trigeminal Neuralgia is not common. There are several ways to get Trigeminal Nerve damage or for the nerves to become irritated. I say nerves because this nerve actually branches off into 3. (Tri)
I've also heard the pain described as lightening flashes, burning flares, etc. It's usually brief but can be excruciating.
I was told years ago, after several surgeries for TMJD, that I had surgically induced Trigeminal Neuralgia. During the surgeries the nerves were damaged, nicked or injured in some way. It caused severe burning flares, several times a day.
Some Dcotors now know (in regard to TMJD) that compression of the nerves can cause the same type pain. Many people with TMJD, who do not have surgical damage can suffer this pain due to muscle spasms compressing the nerves. This is nerve pain and regular medications do not help. Medications like Neurotin, Tegretol, Baclofen and I think some newer ones are used now. Sometimes they help, but do have some side effects that a lot of people can't tolerate.
There has been some discussion on this subject. If you're not familiar with the search feature on the board, it's at top right under the reply tab. You just put in the word or phrase and click search. Any threads on this topic will be pulled up for you.
The information I read says that Doctors can usually diagnose Trigeminal Neuralgia with the patients description of the pain and there are no specific tests. It's a very distinctive type pain and different from anything else. If the Doctor has reason to believe that the compression of the nerves is caused by a tumor or aneurysm, there would be tests for this. They also can evaluate for other causes of compression of the Trigeminal nerves such as diseases of the teeth, jaw and sinuses.
As far as being able to see compressed or damaged nerves with an MRI, I don't think they can do that. I've never seen any info about using tests like an EMG or other tests for nerve damage that they use for other nerve related problems.
I have not researched this a whole lot, just briefly read over some material on the basics.
I was diagnosed by a "Pain Management Specialist". He based the diagnosis on my description and the location of the pain. Also, he said the location of the incisions with the TMJD surgeries would indicate the Trig. Nerves had been disturbed or injured.
I continued to have the burning flares daily, (10 to 15 times a day) up until recently. With splint therapy that has relaxed the muscles, it appears the compression of the nerves has abated a great deal and I only have a "flare" occasionally now. Sometimes very briefly once or twice a day, sometimes none at all.
In my personal experience, if this is caused by compression of the nerves from muscles spasms or other factors related to a TMJD problem, it can be treated by getting the TMJD under control. As the muscles have relaxed, the burning flares have subsided substantially.
My Internist is very aware of this disorder as I'm sure most Doctors are. I've had a few pretty severe escalations of the symtoms in the past few years and went to him to make sure nothing else was going on.
If you have concerns that you may have this caused by something other than TMJD problems, a Neurologist would be who could diagnose and possibly prescibe something for it.
I think there has been some other discussion on the board about this problem and I believe Elaine made a very informative post regarding the Trigeminal Nerves, as well as several other members. I'll see if I can find any of them and bump them up.
Thank you. The reason I ask was I never heard of the condition but when I read the thread I identified with the symptoms. A few months back they did every kind of test imaginable sure that I had some nerve blockage somewhere. The tests showed nothing so they said the problems were probably just caused my my TMJ pressing on ear nerves and that I might want to consider jaw surgery (ive only had arthrosintsis). Thank you for your detailed response.
I am very glad to hear that your condition has somewhat been helped by splint therapy and I will pray it continues to get better.
Trigeminal Neuralgia...????? 
