How is secondary trigeminal neuralgia (TN) differentiated from idiopathic trigeminal neuralgia (TN)?

Updated: Jul 11, 2019
  • Author: Manish K Singh, MD; Chief Editor: Robert A Egan, MD  more...
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Answer

Secondary vs idiopathic trigeminal neuralgia

Symptomatic or secondary trigeminal neuralgia is a more likely consideration than the idiopathic form when pain is associated with hyperesthesia along the course of the fifth nerve or is observed with other cranial neuropathies. Further, consider secondary trigeminal neuralgia in patients with bilateral sensory loss or weakness of the facial muscles or jaw.

Additional investigation may reveal multiple sclerosis (MS), a tumor in the posterior fossa, or a tumor on the trigeminal nerve.

Acoustic neuromas, cerebral aneurysms, trigeminal neuromas, and meningiomas can produce syndromes similar to idiopathic trigeminal neuralgia. Consider these conditions in patients with onset of pain when younger than 40 years, those with predominant forehead and/or orbit pain (ie, first division of the trigeminal nerve), or those with bilateral facial pain. Also consider granulomatous inflammation (eg, tuberculosis, sarcoidosis, Behçet syndrome, collagen vascular diseases) and other vasculitides, as these may affect the trigeminal nerve and simulate trigeminal neuralgia.

Patients with prominent hemifacial spasm, especially if it is continuous, may have tic convulsif, a condition associated with a dilated and ectatic basilar artery or other vascular malformation compressing the trigeminal nerve.

Brain magnetic resonance imaging (MRI) with and without contrast is critical in diagnosing the secondary causes of trigeminal neuralgia.

Failure to properly assess for secondary trigeminal neuralgia is a major potential pitfall. A careful examination of the cranial nerves and an MRI of the brain, especially in an individual who develops the disorder when younger than 60 years, should protect against missing structural lesions (eg, tumor, cerebral aneurysm, acoustic neuroma).


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