Che-Wei Wu1, Feng-Yu Chiang1, Gregory W. Randolph2, Gianlorenzo Dionigi3, Hoon Yub Kim4, Yi-Chu Lin1, Pi-Ying Chang5, I-Cheng Lu5
1 Department of Otolaryngology-Head and Neck Surgery, Kaohsiung Medical University Hospital and Kaohsiung Municipal Siaogang Hospital; Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
2 Division of Thyroid and Parathyroid Endocrine Surgery, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary; Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, USA
3 1st Division of General Surgery, Research Center for Endocrine Surgery, Department of Medicine and Surgery, ASST Sette Laghi Ospedale di Circolo e Fondazione Macchi- Polo Universitario, University of Insubria (Varese-Como),
4 Department of Surgery, Korea University College of Medicine, Seoul, Korea
5 Department of Anesthesiology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
Background: IONM during thyroid surgery is almost always performed by attaching a recording electrode to endotracheal tube (ETT)-based surface electrodes. Anatomically, the left and right thyroarytenoid muscles are attached to the anterior part of the inner surface of the thyroid cartilage (TC). Therefore, electrodes on the TC are an alternative means to assess the function of the thyroarytenoid muscle and the recurrent laryngeal nerve (RLN). This experimental study aimed to determine the feasibility of using adhesive electrodes on TC for recording of evoked laryngeal electromyography (EMG) during IONM.
Method: Eight piglets (16 nerve sides) were enrolled, and electrically evoked EMG was recorded from both the ETT-based electrodes and the adhesive pre-gelled electrodes put on the TC. The evoked EMG waveforms were measured and analyzed.
Results: Both ETT and TC recording electrodes recorded typical evoked laryngeal EMG waveforms from the bilateral vagus nerve and RLNs stimulation with 1 mA current. The mean recorded amplitude was 969 +/- 202 µV from ETT, and 617 +/- 112 µV from adhesive TC electrodes during the RLN stimulation.
Conclusion: Trans-cartilage recording is feasible during IONM. Future animal and clinical studies are needed to evaluate its stability during surgical manipulation, and the accuracy in reflecting a neurophysiologic event.