Computed tomography's ability to predict sacrifice of hypoglossal nerve at resection

Objective: To assess whether preoperative computed tomography (CT) scan can determine if the hypoglossal nerve (cranial nerve XII) will be sacrificed in floor-of-mouth, oral tongue, and tongue base tumor resections. Study Design: Retrospective review. Methods: Patients who underwent resection of floor-of-mouth, oral tongue, and tongue base tumors from 1990 to 1999 were identified. Preoperative CT scans were reviewed by a neuroradiologist. The postoperative status of cranial nerve XII was predicted to be "saved" or "sacrificed." Hypoglossal nerve "sacrifice" was predicted if the fat planes surrounding the takeoff of the proximal lingual artery were obliterated by tumor. The nerve was determined to be sacrificed or spared during resection by review of the operative report. Results: Of the 45 patients, 14 tumors were predicted radiographically to involve the hypoglossal nerve. Twenty-seven of 31 nerves that were predicted to be saved were saved at the time of surgery. Seven of 14 nerves that were predicted to be sacrificed were sacrificed at the time of surgery. The sensitivity was 0.64 (95% confidence interva] [CI], 0.35-0.86) with a specificity of 0.79 (95% CI, 0.70-0.87). The positive predictive value was 0.50 (95% CI, 0.27-0.68) with a negative predictive value of 0.87 (95% CI, 0.77-0.95). Conclusions: The ability to predict preoperatively whether a tumor can be resected without sacrificing the hypoglossal nerve would be an important factor in determining management of these tumors. The results indicate that CT scan accurately predicts the ability of the surgeon to spare the hypoglossal nerve (negative predictive value, 87%) with a specificity of 0.79.