Spontaneous regeneration of recurrent laryngeal nerve following long-term vocal fold paralysis in humans: Histologic evidence

Authors

  • Donghui Chen MD,

    1. Institute of Biomedical Engineering, Second Military Medical University , #Shanghai, China
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    • Donghui Chen, MD, and Shicai Chen, MD, contributed equally to this work.

  • Shicai Chen MD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Changhai Hospital, Second Military Medical University , Shanghai, China
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    • Donghui Chen, MD, and Shicai Chen, MD, contributed equally to this work.

  • Wei Wang MD,

    1. Department of Otorhinolaryngology–Head and Neck Surgery, Changhai Hospital, Second Military Medical University , Shanghai, China
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  • Chuansen Zhang PhD,

    1. Institute of Biomedical Engineering, Second Military Medical University , #Shanghai, China
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  • Hongliang Zheng MD

    Corresponding author
    1. Department of Otorhinolaryngology–Head and Neck Surgery, Changhai Hospital, Second Military Medical University , Shanghai, China
    • Department of Otorhinolaryngology–Head and Neck Surgery, Changhai Hospital, Shanghai 200433, China
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  • This work was supported by Grants No. 30772415, 81070774, and 81070775 for science research from the National Natural Science Foundation of China and Grants No. 09JC1400500 and 10XD1405500 from the Science and Technology Commission of Shanghai Municipality. The authors have no other funding, financial relationships, or conflicts of interest to disclose.

Abstract

Objectives/Hypothesis:

To validate the occurrence of spontaneous regeneration of the recurrent laryngeal nerve (RLN) in patients with symptomatic vocal fold paralysis (VFP).

Study Design:

Histologic study.

Methods:

Between June 2008 and February 2009, 29 patients with symptomatic unilateral VFP caused by thyroid surgery were continuously enrolled in this study, with 30 normal RLNs serving as the control. The denervation course was from 7 to 74 months. Intraoperative exploration was performed to identify the sites and types of RLN lesions. The status of RLN regeneration was detected by histologic examination, and the number of myelinated axons was counted.

Results:

Intraoperative exploration showed that RLN was transected in 24 cases, and the continuity of the RLN stump was recognized in the five other cases. Connective tissue connected the distal and the proximal ends of all transected RLNs under a surgical microscope. Light microscopy showed varying numbers (17–259) of abnormal myelinated axons in these injured RLNs; the maximum was less than 40% of those of normal RLNs (658 ± 79). Electron microscopy also demonstrated that abnormal myelinated axons with small diameters commonly existed in all injured RLNs, with dark myelin clumps without axons (Bungner bands) and fibrotic components.

Conclusions:

The present study demonstrates that a varying degree of spontaneous RLN regeneration is substantially engaged in the process of subclinical reinnervation following laryngeal denervation in humans, which may account for different clinical characteristics and outcomes of VFP.

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