Neurinoma of the trigeminal root and atypical trigeminal neuralgia: case report and review of the literature.

BACKGROUND

Neurinomas of the trigeminal nerve are a rare entity: those located in the posterior fossa account for 20% of all cases. In the majority of cases, the clinical presentation begins with fifth cranial nerve involvement producing a constant pain associated with other cranial nerve palsy and cerebellar signs.

METHODS

We report the clinical features, neuroradiological imagings, and management of a case of trigeminal neurinoma located in the cerebellopontine angle, arising from the Vth cranial nerve root, presenting with an atypical trigeminal neuralgia; moreover, we analyze similar cases reported in the literature and we discuss whether pain can be produced by a neurinoma that arises central to the ganglion.

RESULTS

The tumor presented with an atypical trigeminal neuralgia characterized by constant trigeminal pain with paroxystical burns, hyperesthesia and hyperactive autonomic dysfunction. Neuroradiological examinations provided the best preoperative localization of this lesion, allowing better planning of the surgical approach, considering the large size of this tumor. A retromastoid incision and posterior fossa craniectomy approach was used, with complete excision of the tumor. The paraxysmal sharp pain and hyperesthesia disappeared completely, but the constant burning pain persisted although it was less intense. At an 8-month follow-up examination, the patient showed a progressive improvement of clinical symptoms and control magnetic resonance imaging (MRI) showed the complete removal of the neoplasm and the absence of residuals or recurrences.

CONCLUSION

Although in a high percentage of cases of atypical trigeminal neuralgia a neurovascular conflict might be suspected, the review of the present case suggests that the hypothesis of a trigeminal neurinoma must be investigated both with adequate neuroradiological procedures and/or microsurgical exploration of the trigeminal root.