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OBJECTIVESurgery for tumors around the jugular foramen has significant risks of dysphagia and vocal cord palsy due to possible damage to the lower cranial nerve functions. For its treatment, long-term tumor control by maximum resection while avoiding permanent neurological damage is required. To accomplish this challenging goal, the authors developed an intraoperative continuous vagus nerve monitoring system and herein report their experience with this novel neuromonitoring method.METHODSFifty consecutive patients with tumors around the jugular foramen (34 jugular foramen schwannomas, 11 meningiomas, 3 hypoglossal schwannomas, and 2 others) who underwent microsurgical resection under continuous vagus nerve monitoring within an 11-year period were retrospectively investigated. Evoked vagus nerve electromyograms were continuously monitored by direct 1-Hz stimulation to the nerve throughout the microsurgical procedure.RESULTSThe average resection rate was 96.2%, and no additional surgery was required in any of the patients during the follow-up period (average 65.0 months). Extubation immediately after surgery and oral feeding within 10 days postoperatively were each achieved in 49 patients (98.0%). In 7 patients (14.0%), dysphagia and/or hoarseness were mildly worsened postoperatively at the latest follow-up, but tracheostomy or gastrostomy was not required in any of them. Amplitude preservation ratios on intraoperative vagus nerve electromyograms were significantly smaller in patients with postoperative worsening of dysphagia and/or hoarseness (cutoff value 63%, sensitivity 86%, specificity 79%).CONCLUSIONSIntraoperative continuous vagus nerve monitoring enables real-time and quantitative assessment of vagus nerve function and is important for avoiding permanent vagus nerve palsy, while helping to achieve sufficient resection of tumors around the jugular foramen.

Sarcoidosis is a systemic granulomatous disease with unknown cause, which very rarely occurs exclusively in the central nervous system. The authors performed biopsy sampling of a mass that developed in the left tentorium cerebelli that appeared to be a malignant tumor. The mass was diagnosed as a sarcoid granuloma, which was confirmed with the onset of antibody reaction product against Propionibacterium acnes. Findings suggesting sarcoidosis to be an immune response to P. acnes infection have recently been reported, and they give insight for diagnosis and treatment of this disease. The authors report the possible first case that was confirmed with P. acnes infection in a meningeal lesion in solitary neurosarcoidosis.