Trochlear nerve neurinoma associated with a giant thrombosed dissecting aneurysm of the contralateral vertebral artery.

The authors encountered the unusual case of a 57-year-old man with a right trochlear nerve neurinoma associated with a giant thrombosed dissecting aneurysm of the left vertebral artery. The right trochlear nerve neurinoma was subtotally removed via the right subtemporal transtentorial route. The trochlear nerve entered the tumor directly posterolaterally. The left vertebral artery was clipped just proximal to the thrombosed dissecting aneurysm via the left lateral suboccipital approach. The patient was discharged without neurologic deficits except for the right trochlear nerve palsy. To our knowledge, this seems to be the first reported case of such an occurrence.