Three-Dimensional Reconstruction Of Cranial Nerves And Clinical Application Exploration In Vestibular Schwannomas Surgery

Objective3D imaging of cranial nerves nowadays is a significant technology, it enables the neurosurgeons to preoperatively evaluate the shift or morphological changes caused by compression. In this study, the authors try to apply diffusion tensor imaging in healthy subjects, the patients with skull base space-occupying lesion to track and fulfill3D reconstruction of cranial nerves, then verify its possibility, and discuss the application value of this technology in vestibular schwannoma through statistical analysis.Methods Under the condition of high field strength of3.0T magnetic resonance Imaging (MRI), we use three different special scan sequence, including3D fast spoiled gradient echo sequence (3D FSPGR), fast Imaging Empolying Steady State Acquisition (FIESTA) and Diffusion tensor Imaging (DTI), to fulfill a preliminary scan of all subjects. DTI data integrates into3D Slicer software for tracking and reconstruction of fiber bundles, combined with3D FSPGR or FIESTA in software to position the location and the course of cranial nerves. In skull base lesion cases and vestibular schwannoma cases, we preoperatively track related cranial nerve and complete3D reconstruction of the tumor body, in order to show adjacent, encasing, invading relations between cranial nerve and surrounding lesions. Combined with intraoperative microscope and neural electrophysiological monitoring, we can verify the location of the related cranial nerve and facial nerve.Result By diffusion tensor imaging technology, this study can determine the location, course, and morphological changes of the relevant cranial nerve in the healthy subjects and patients with typical skull base lesions or vestibular schwannoma. Detailed fibers of the cranial nerves were depicted. Optic pathway showed perfect3D streamline body, especially the posterior of optic chiasm. Oculomotor nerve coursed from the brainstem to the cavernous sinus distally, which also had high fidelity. Trigeminal nerve allowed visualization of gasserian ganglion as cisternal segment. Cisternal parts of abducent nerve, facial/vestibulocochlear nerve, vagus nerve, hypoglossal nerve were also imaged well. In10cases of skull base space-occupying lesion,3D-spatial relationship between cranial nerve and space-occupying lesions via3D reconstruction of tumor and tracking of cranial nerve fiber, could be showen, which includes the shift of trigeminal nerve, abducent nerve, the nerve to some degree. Its accuracy is verified though surgery. In21cases of patients with vestibular schwannoma, fiber bundle of facial nerve in19cases (19/21,90.5%), anatomical position and course from the brain stem to IAC all can be shown well. The location of Facial nerve in cerebellopontine angle related to tumor in17cases (17/19,89.5%) were conformed by intraoperative microscope and neural electrophysiological monitoringConclusion Supported by DTI and3D slicer,3D reconstruction of cranial nerve is feasible in normal and pathological circumstances. This technique could preoperatively judge the adjacent, encasing, invading relationships between cranial nerve and space-occupying lesions of the skull base, especially could improve the preoperative plan of vestibular schwannoma surgery and guide operation performed by surgeon, and has a good prospect of clinical application.