Abstract

Background
Various lesions affecting the trigeminal nerve entry zone may produce trigeminal neuralgia, and include tortuous vessels, aneurysms, arteriovenous malformations, and tumors. However, pontine in- farction or pontine multiple sclerosis(MS) lesion has not been well recognized as a cause of trigeminal neuralgia. Here we report two patients with a pontine lesion(ischemic or demyelinating) transecting the trigeminal pathways resulting with trigeminal neuralgia. These are very rare cases of unusual causes of trigeminal neuralgia. Case: A 55-year-old man presented with severe lacinating pain in the right V2 and V3 distributions. Magnetic resonance imaging of the brain demonstrated a small linear infarct at the root entry zone of the right trigeminal nerve in the pons. The other 30-year-old woman developed electric shocklike pain in the same distributions as a symptom of MS. Brain MRI showed multiple patchy cerebral lesions including right lateral portion of the pons. Conclusion: The mechanism for the trigeminal neuralgia due to pontine lesion may be increased neuronal activity in the trigeminal fascicles and nucleus. Our patients illustrate that the differential diag- nosis of trigeminal neuralgia should include pontine infarction or pontine MS lesion.