MRI Tractography Detecting Cranial Nerve Displacement in a Cystic Skull Base Tumor.

A 37-year-old man came to our neurosurgical department with a 2-month history of a progressive invalidating balance disorder. Cerebral magnetic resonance imaging found a T2-weighted hypersignal lesion of the right cerebellopontine angle that severely compressed the brainstem, however the position of cranial nerves was not clearly identified. The new MRI diffusion tool, tractography, allowed to reconstruct the trajectory of cranial nerves that were displaced by the tumor. As such, the acoustic facial bundle was severely flattened posteriorly and superiorly, while the lower nerves were pushed inferiorly. Effective neurosurgical decompression was performed and confirmed the position of cranial nerves V-XII. The patient was discharged and returned home without any cranial nerve deficit. This case illustrates how advances in imaging can now better describe the anatomy surrounding brain tumors and make surgery safer to the benefit of patients.