LAUSR

Trigeminal schwannomas are benign lesions arising from the Schwann cells of the trigeminal nerve. This is an unusual tumor that accounts for less than 0.4% of intracranial pathologies, even though they are the second most frequent schwannoma after the vestibular schwannoma. The tumor spreads along the natural course of the V nerve at its cisternal portion, along the ganglion inside Meckel's cave or through its peripheral division. Even though the tumor can reach great size and become multicompartmental. We present a 51-yr-old woman, with an history of 3 mo of incapacitating facial pain, that was found on examination to be on the territory of the third division of the trigeminal nerve on the right side. The MRI depicted a large homogeneous enhancing lesion at the base of the right middle fossa with extension through the petrous apex to the most superior and medial part of the posterior fossa. The patient was operated by the senior author, through a middle fossa approach, dissecting between the two layers of the middle fossa dura (the apparent inner and the true outer layer of the cavernous sinus), the so called middle fossa "peeling". We achieved total resection of the tumor, but the patient presented after surgery with facial nerve paresis. This is thought to be related to geniculate ganglion manipulation, as it was unprotect by bone at the middle fossa and the patient maintained lacrimal function (post-geniculate alteration). It resolved completely after 6 mo. The patient consented to publication of her images.