Imaging Studies
In the ED, providers may consider a CT scan of the brain or maxillofacial region to evaluate for alternative etiology such as dental or sinus disease. However, trigeminal neuralgia (TN) is a clinical diagnosis and the majority of patients with characteristic history and normal neurologic examination may be treated without further workup or imaging.
Some physicians recommend elective MRI with MRA for all patients to exclude an uncommon mass lesion or aberrant vessel compressing the nerve roots.
Consider an outpatient MRI to identify patients with structural causes or exclude other possible causes of facial pain.
In a published practice parameter, the American Academy of Neurology stated that because of inconsistency of studies, there was insufficient evidence to support or refute the usefulness of MRI or a specific MRI technique to identify vascular anomalies. The recommendation was that, for patients with TN, routine imaging may be considered to identify symptomatic TN, and this was graded as a Level C or possibly effective action. [8]
There is no strong evidence to support the use of evoked potentials. [1]
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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.
