World Journal of Surgery

, Volume 40, Issue 6, pp 1373–1381 | Cite as

Severity of Recurrent Laryngeal Nerve Injuries in Thyroid Surgery

  • Gianlorenzo Dionigi
  • Che-Wei WuEmail author
  • Hoon Yub Kim
  • Stefano Rausei
  • Luigi Boni
  • Feng-Yu Chiang
Original Scientific Report



Few studies in the literature have reported recovery data for different types of recurrent laryngeal nerve injuries (RLNIs). This study is the first attempt to classify RLNIs and rank them by severity.


This prospective clinical study analyzed 281 RLNIs in which a true loss of signal was identified by intraoperative neuromonitoring (IONM), and vocal cord palsy (VCP) was confirmed by a postoperative laryngoscope. For each injury type, the prevalence of VCP, the time of VCP recovery, and physical changes on nerves were analyzed. Additionally, different RLNI types were experimentally induced in a porcine model to compare morphological change.


The overall VCP rate in at-risk patients/nerves was 8.9/4.6 %, respectively. The distribution of RLNI types, in order of frequency, was traction (71 %), thermal (17 %), compression (4.2 %), clamping (3.4 %), ligature entrapment (1.6 %), suction (1.4 %), and nerve transection (1.4 %). Complete recovery from VCP was documented in 91 % of RLNIs. Recovery time was significantly faster in the traction group compared to the other groups (p < 0.001). The rates of temporary and permanent VCP were 98.6 and 1.4 % for traction lesion, 72 and 28 % for thermal injury, 100 and 0 % for compression injury, 50 and 50 % for clamping injury, 100 and 0 % for ligature entrapment, 100 and 0 % for suction injury, and 0 and 100 % for nerve transection, respectively. Physical changes were noted in 14 % of RLNIs in which 56 % of VCP was permanent. However, among the remaining 86 % IONM-detectable RLNIs without physical changes, only 1.2 % of VCP was permanent. A porcine model of traction lesion showed only distorted outer nerve structure, whereas the thermal lesion showed severe damage in the inner endoneurium.


Different RNLIs induce different morphological alterations and have different recovery outcomes. Permanent VCP is rare in lesions that are visually undetectable but detectable by IONM. By enabling early detection of RLNI and prediction of outcome, IONM can help clinicians plan intra- and postoperative treatment.


Recurrent Laryngeal Nerve Thermal Injury Vocal Cord Palsy Recurrent Laryngeal Nerve Palsy Traction Injury 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The animal experiments in this study were supported by grants from the Kaohsiung Medical University Hospital (KMUH 103-3T07, 103-3R36) and the Ministry of Science and Technology, Taiwan. (MOST 103-2314-B-037-037- MY2).The authors are grateful to Dr. Pao-Chu Hun (Veterinarian, Laboratory Animal Center, KMU), Dr. Pi-Ying Chang, Dr. I-Cheng Lu (Anesthesiologists, KMUH), and Dr. Kuo-Bow Tsai (Pathologist, KMU) for their valuable technical assistance.

Compliance with ethical standards

Conflict of Interest

The authors have no other funding, financial relationships, or conflicts of interest to disclose.


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Copyright information

© Société Internationale de Chirurgie 2016

Authors and Affiliations

  • Gianlorenzo Dionigi
    • 1
  • Che-Wei Wu
    • 2
    Email author
  • Hoon Yub Kim
    • 3
  • Stefano Rausei
    • 1
  • Luigi Boni
    • 1
  • Feng-Yu Chiang
    • 2
  1. 1.1st Division of General Surgery, Department of Surgical Sciences and Human Morphology, Research Center for Endocrine SurgeryUniversity of Insubria (Varese-Como)VareseItaly
  2. 2.Department of Otolaryngology-Head and Neck Surgery, Kaohsiung Medical University Hospital, Faculty of Medicine, College of MedicineKaohsiung Medical UniversityKaohsiung CityTaiwan
  3. 3.Division of Breast and Endocrine Surgery, Department of Surgery, Minimally Invasive Surgery and Robotic Surgery Center, Korea University HospitalKorea University College of MedicineSeoulKorea

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