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Objective: Neurophysiological intraoperative monitoring of the glossopharyngeal nerve has been performed only with needle electrodes inserted into the pharyngeal muscles or soft palate. We describe a noninvasive method of monitoring this cranial nerve., Methods: A 30-year-old man who presented with headache, as well as speech and swallowing difficulty, underwent surgical resection of a right vagus nerve schwannoma. Neurophysiological intraoperative monitoring of multiple lower cranial nerves, including the glossopharyngeal and vagus nerves, was performed., Results: The glossopharyngeal nerve was monitored with an adhesive surface electrode mounted on the cuff of a laryngeal mask airway, and the vagus nerve was monitored with a similar electrode mounted on the endotracheal tube. Successful monitoring allowed separation of the glossopharyngeal nerve from the tumor, and there was no postoperative swallowing deficit., Conclusion: Monitoring of the glossopharyngeal nerve with surface electrodes is possible and reliable, but it must be combined with vagus nerve monitoring.

A 51-year-old man is reported who was suffering from an extensive right-sided glossopharyngeal neurinoma (4.6 x 3.4 cm). The patient was admitted with a history of headache for six to seven years and vomiting for two years accompanied by a progressive hearing loss, tinnitus and dizziness during the last year. Audiometry indicated a perceptive deafness in the whole frequency range up to 70 dB HL, while electronystagmography (ENG) showed a loss of vestibular function of the right side, but there were no signs of a jugular foramen syndrome. Magnetic resonance imaging (MRI) revealed a large tumor portion in the right cerebello-pontine angle with only a small part in the jugular foramen. The neurinoma was completely removed by microsurgery through a suboccipital approach with preservation of nerves VII-XII. The postoperative course was uneventful and normal function of facial and caudal cranial nerves (Nn IX-XII) were proven by electromyography and magnetic stimulation, with exception of a transitory hypesthesia in the palatine region which completely normalized within a few months. The right-sided hearing loss was unchanged, but vertigo improved. In comparison with literature review the lack of temporary or permanent postoperative dysfunctions of caudal cranial nerves as well as of the facial nerve was extraordinary in the reported case.