Diffusion-Weighted Magnetic Resonance Neurography for Parapharyngeal Schwannomas: Preoperative Determination of the Originating Nerves

Objective: The aim of this study was to assess the feasibility of diffusion-weighted (DW) magnetic resonance neurography (MRN) for determining the originating nerve of parapharyngeal schwannomas preoperatively. Methods: Six patients who underwent DW-MRN preoperatively for a parapharyngeal schwannoma were studied. Prediction of the originating nerve was performed. With the conventional method, a tumor showing "separation" between the internal jugular vein and carotid artery was determined to originate from the vagus nerve, with "no separation" from the sympathetic chain. With DW-MRN, the relationships between the vagus nerve and sympathetic chain to the tumor were characterized as "connected" or "dislocated." A nerve connected to the tumor was determined as the origin. Results: Surgeries revealed that the origins included 1 vagus nerve and 5 sympathetic chains. Using a conventional method, all 6 cases were diagnosed correctly, whereas DW-MRN successfully predicted only 4 cases with a sympathetic chain origin. Conclusions: The DW-MRN is a feasible approach for determining an originating nerve.