[The utility of presurgical simulation of microvascular decompression by MR virtual endoscopy].

OBJECTIVE: We conducted the present study to assess the utility of virtual endoscopy (VE) created by volume rendering of MR images in presurgical simulation for trigeminal neuralgia (TN) and hemifacial spasm (HFS).

METHODS: In 12 patients (six with TN and six with HFS), we presurgically evaluated the anatomy of the cerebellopontine angle (CPA) region and simulated an appropriate surgical approach by VE of heavy T2-weighted imaging and MR angiography.

RESULTS: The three-dimensional (3-D) relations of neurovascular structures in the CPA region were compatible between on-VE and on-the-intraoperative view in all patients. The compression sites and the major offending vessels were correctly depicted, except for two small branches as the offending vessel. The other important structures affecting the surgical procedure were identified as major petrosal veins in all patients with TN, a vertebral artery in three with HFS, and a large cerebellar flocculus in three with HFS. Transposition of the offending vessels was performed as simulated in all patients with TN and in three patients with HFS. All patients had an excellent surgical outcome.

CONCLUSIONS: Presurgical simulation by VE in patients with TN and HFS is a novel method that provides excellent visualization of the 3-D relations of neurovascular structures in the CPA region and allows us to accomplish successful and safe surgery.