Vocal cord paralysis predicted by neural monitoring electrophysiologic changes with recurrent laryngeal nerve compressive neuropraxic injury in a canine model

Sidharth V Puram; Harold Chow; Che-Wei Wu; James T Heaton; Dipti Kamani; Gautham Gorti; Feng Yu Chiang; Gianlorenzo Dionigi; Marcin Barczyński; Rick Schneider; Henning Dralle; Kerstin Lorenz; Gregory W Randolph

doi:10.1002/hed.24225

Vocal cord paralysis predicted by neural monitoring electrophysiologic changes with recurrent laryngeal nerve compressive neuropraxic injury in a canine model

Head Neck. 2016 Apr:38 Suppl 1:E1341-50. doi: 10.1002/hed.24225. Epub 2015 Sep 8.

Authors

Affiliations

¹ Division of Thyroid and Parathyroid Surgery, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts.
² Department of Otorhinolaryngology-Head and Neck Surgery, Kaohsiung Medical University Hospital, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
³ Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
⁴ Department of Surgical Sciences and Human Morphology, Division of Surgery, University of Insubria - School of Medicine, Varese, Italy.
⁵ Department of Endocrine Surgery, Jagiellonian University Medical College, Krakow, Poland.
⁶ Department of General, Visceral, and Vascular Surgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
⁷ Division of Surgical Oncology, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.

PMID: 26348472
DOI: 10.1002/hed.24225

Abstract

Background: Recurrent laryngeal nerve (RLN) injury is a known complication of thyroid/parathyroid surgery. Intraoperative nerve monitoring (IONM) has been used to gain more information regarding the functional status of the RLN intraoperatively; however, the electromyography (EMG) parameters of RLN after nontransection neuropraxic compressive injury remain unknown.

Methods: We developed a canine model to identify IONM EMG correlates of postoperative vocal cord paralysis (VCP) using a standardized method to simulate surgical RLN compression sufficient to cause VCP.

Results: Compression nerve injury decreased EMG amplitude and increased EMG latency, with a 60% increase in RLN threshold stimulation compared to preinjury values. If RLN amplitude decreases by 80% with an absolute amplitude of 300 μV or less in combination with a latency increase of 10% or more, then nerve injury and associated VCP is likely.

Conclusion: These results may help surgeons to prognosticate postoperative neural function and intraoperative decision-making regarding contralateral thyroid surgery. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1341-E1350, 2016.

Keywords: endocrine; injury; intraoperative nerve monitoring (IONM); recurrent laryngeal nerve; thyroid surgery; vocal cord palsy.

MeSH terms

Animals
Dogs
Electromyography
Female
Intraoperative Neurophysiological Monitoring*
Male
Recurrent Laryngeal Nerve Injuries / pathology*
Thyroidectomy
Vocal Cord Paralysis / diagnosis*
Vocal Cord Paralysis / pathology