Epidermoid cyst presenting as isolated trigeminal neuralgia - two case reports.

PURPOSE: Symptomatic TN accounts for up to 15% of all TN. Though there are many established "red flag" signs, it is still sometimes difficult to sift symptomatic from classic TN. We herein report two cases of isolated TN with normal neurologic examinations and then tissue proved as epidermoid cyst.

CASE 1: A 17-year-old girl presented with paroxysmal intense pain mixed dull background pain at right mandibular region for one month. The blink reflex demonstrated brainstem lesion and brain magnetic resonance imaging (MRI) revealed a huge lobulated tumor in right cerebellopontine angle (CPA) with obvious brainstem compression. Her right facial pain was nearly completely disappeared postoperatively.

CASE 2: The 48-year-old woman had chronic paroxysmal electric-like and burning pain in left V3 region for more than 5 years. Because of refractory pain, brain MRI was arranged and showed a non-enhancing cystic lesion at left CPA. Post operative complications occurred as left multiple lower cranial nerve palsies and Horner syndrome, and truncal ataxia. Her facial pain was completely free after 1 month follow up.

CONCLUSION: In the first patient, teenage onset, abnormal trigeminal reflex, and early developing background pain struck us directly to symptomatic TN. In the second case, we suspected symptomatic TN with uncertainty before image study. TN could be the isolated initial symptom of CPA epidermoid cysts. In consideration about pretty high prevalence of symptomatic TN, physicians should be more alert and straightforward arrange neuroimage when facing TN patients with atypical presentation.