Trigeminal Neuralgia

There is no single test to diagnose TN.  Diagnosis is generally based on the patient’s medical history and description of symptoms, a physical exam, and a thorough neurological examination by a physician.  Other disorders, such as post-herpetic neuralgia, can cause similar facial pain, as do syndromes such as cluster headaches.  Injury to the trigeminal nerve (perhaps the result of sinus surgery, oral surgery, stroke, or facial trauma) may produce neuropathic pain, which is characterized by dull, burning, and boring pain. 

http://trigeminalinfo.blogspot.com/

Most TN patients undergo a standard magnetic resonance imaging scan to rule out a tumor or multiple sclerosis as the cause of their pain.  This scan may or may not clearly show a blood vessel on the nerve.  Magnetic resonance angiography, which can trace a colored dye that is injected into the bloodstream prior to the scan, can more clearly show blood vessel problems and any compression of the trigeminal nerve close to the brainstem.

http://www.gammaknifeonline.in/gamma_knife_for_trigeminal_neuralgia