İrem İlgezdi-Kaya1,2,3, Elif Ilgaz-Aydınlar4, Pınar Yalınay-Dikmen4, Ramazan Sarı5, İlhan Elmacı5. 1. Istanbul Medical Faculty, Department of Neurology and Neurophysiology, Istanbul University, Istanbul, Turkey. iremilgezdi@yahoo.com. 2. Department of Neurology and Neurophysiology, Istanbul University Istanbul Medicine Faculty, Istanbul, Turkey. iremilgezdi@yahoo.com. 3. EEG-EMG unit, Topkapi Mahallesi Turgut Ozal Millet Caddesi Istanbul Universitesi Istanbul Tip Fakultesi Norolojik, Bilimler Binasi Kat:1, Istanbul, Turkey. iremilgezdi@yahoo.com. 4. Department of Neurology, Acıbadem Maslak Hospital, Istanbul, Turkey. 5. Department of Neurochirurgie, Acıbadem Maslak Hospital, Istanbul, Turkey.
Abstract
PURPOSE: Schwannoma, a tumor originating from the peripheral nervous system, may arise from the vagus nerve, although it is not very often. Injury of the vagus nerve by surgical attempts may have consequences that will seriously affect the patient's quality of life. In recent years, continuous monitoring of the laryngeal adductor reflex (LAR) has become a promising methodology for evaluating vagus nerve function intraoperatively. We refer to our experience changing our surgical strategy due to concurrent deterioration in LAR and CoMEPs intraoperatively. We also provide a literature review and summarize the current knowledge of this technique. METHODS: The LAR was elicited and recorded by an electromyographic endotracheal tube in a 36-year-old man diagnosed with vagal nerve schwannoma. Subdermal needle electrodes were placed in both cricothyroid (CTHY) muscles for corticobulbar motor evoked potentials (CoMEPs) recording. RESULTS: Recordings of ipsilateral LAR and CTHY CoMEPs were obtained despite preoperative ipsilateral cord vocalis weakness. The surgical strategy was altered after the simultaneous decrease of CTHY CoMEPs and LAR amplitudes, and the surgery was completed with subtotal resection. No additional neurological deficit was observed in the patient except dysphonia, which resolved within a few weeks after the surgery. CONCLUSIONS: We conclude that LAR with vagal nerve CoMEPs are two complementary methods and provide reliable information about the functional status of the vagus nerve during surgery.
PURPOSE: Schwannoma, a tumor originating from the peripheral nervous system, may arise from the vagus nerve, although it is not very often. Injury of the vagus nerve by surgical attempts may have consequences that will seriously affect the patient's quality of life. In recent years, continuous monitoring of the laryngeal adductor reflex (LAR) has become a promising methodology for evaluating vagus nerve function intraoperatively. We refer to our experience changing our surgical strategy due to concurrent deterioration in LAR and CoMEPs intraoperatively. We also provide a literature review and summarize the current knowledge of this technique. METHODS: The LAR was elicited and recorded by an electromyographic endotracheal tube in a 36-year-old man diagnosed with vagal nerve schwannoma. Subdermal needle electrodes were placed in both cricothyroid (CTHY) muscles for corticobulbar motor evoked potentials (CoMEPs) recording. RESULTS: Recordings of ipsilateral LAR and CTHY CoMEPs were obtained despite preoperative ipsilateral cord vocalis weakness. The surgical strategy was altered after the simultaneous decrease of CTHY CoMEPs and LAR amplitudes, and the surgery was completed with subtotal resection. No additional neurological deficit was observed in the patient except dysphonia, which resolved within a few weeks after the surgery. CONCLUSIONS: We conclude that LAR with vagal nerve CoMEPs are two complementary methods and provide reliable information about the functional status of the vagus nerve during surgery.