History
History is the most important factor in the diagnosis of typical or classical trigeminal neuralgia (TN). Symptomatic trigeminal neuralgia secondary to intracranial processes may have a different history.
Nature of pain
Pain is brief and paroxysmal, but it may occur in volleys of multiple attacks.
Pain is stabbing or shock-like and is typically severe.
Distribution of pain
One or more branches of the trigeminal nerve (usually maxillary or mandibular in unilateral distribution) are involved.
Pain is unilateral in classical trigeminal neuralgia. Bilateral pain suggests symptomatic trigeminal neuralgia. [3]
Duration of pain is typically from a few seconds to 1–2 minutes. Pain may occur several times a day; patients typically experience no pain between episodes.
Trigger points
Various triggers may commonly precipitate a pain attack. Light touch or vibration or even talking can provoke attacks.
Activities such as shaving, face washing, or chewing often trigger an episode.
Stimuli as mild as a light breeze may provoke pain in some patients.
Pain provokes brief muscle spasm of the facial muscles, thus producing the tic.
There is a short refractory period after an attack where you cannot evoke a new attack with repeated stimulation to the same area. [1]
Physical
Physical examination findings should show no abnormality unless there is a prior or concommitant neurologic process. A normal neurologic examination is part of the definition of typical or classic trigeminal neuralgia (TN). Perform a careful examination of the cranial nerves, including the corneal reflex.
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Be alert to the presence of any abnormality on physical examination. Abnormality suggests that the pain syndrome is secondary to another process.
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Trigeminal sensory deficits suggest symptomatic trigeminal neuralgia.
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Remember that patients report pain following stimulation of a trigger point; thus, some patients may limit their examination for fear of stimulating these points.
Causes
Most patients' conditions are idiopathic, but compression of the trigeminal roots by tumors or vascular anomalies may cause similar pain (see Pathophysiology). The most common cause of nerve compression is from an artery pulsating against the nerve.
There are documented cases of development of TN following opthalmic surgery in rare cases. [7]
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Microscopic demonstration of demyelination in primary trigeminal neuralgia. A tortuous axon is surrounded by abnormally discontinuous myelin. Electron microscope, 3, 300 X.
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MRI with high resolution on the pons demonstrating the trigeminal nerve root. In this case, the patient with trigeminal neuralgia has undergone gamma-knife therapy, and the left-sided treated nerve (arrow) is enhanced by gadolinium.
