Whitney Liddy

The electrophysiology of thyroid surgery: electrophysiologic and muscular responses with stimulation of the vagus nerve, recurrent laryngeal nerve, and external branch of the superior laryngeal nerve

Correlation of physiologically important electromyographic (EMG) waveforms with demonstrable muscle activation is important for the reliable interpretation of evoked waveforms during intraoperative neural monitoring (IONM) of the vagus nerve, recurrent laryngeal nerve (RLN), and external branch of the superior laryngeal nerve (EBSLN) in thyroid surgery.

Mechanism of Injury

Causes of recurrent laryngeal nerve (RLN) injury during thyroidectomy are varied, with most injuries resulting from the following surgical errors: sectioning of the nerve, ligation, traction, clamping injury, suction, compression, contusion, electrical and thermal injury. Surgeons underestimate the actual rate of RLN injury. Intraoperative nerve monitoring (IONM) during thyroidectomy, parathyroidectomy, or related central neck procedures can elucidate actual or potential mechanisms of RLN injury that were previously unknown to the thyroid surgeon, especially in visually intact nerves. IONM is useful in open conventional thyroid surgery for localizing the point of disrupted nerve conduction in addition to identifying how and when the RLN was injured. Studying the mechanisms of RLN injury during thyroidectomy is instructive for future operations and may allow for identification of potentially reversible causes of RLN injury. During thyroidectomy and parathyroidectomy, intraoperative RLN injury is typically associated with a visually intact RLN rather than a transected nerve. The anterior motor branch of a RLN bifurcating near the ligament of Berry is particularly at risk of traction injury. Traction injury is the most frequent cause of postoperative vocal cord palsy.

Changes in electromyographic amplitudes but not latencies occur with endotracheal tube malpositioning during intraoperative monitoring for thyroid surgery: Implications for guidelines

During intraoperative neural monitoring (IONM) in thyroid and parathyroid surgery, endotracheal (ET) tube migration can result in a decrease in vocalis electromyographic (EMG) amplitude without a concordant latency elevation during stimulation of the recurrent laryngeal nerve (RLN).

ROS1 Rearrangement in Thyroid Cancer.

BACKGROUND Aberrations involving the ROS1 gene have not been reported in thyroid cancer. Here, a case of ROS1-associated thyroid cancer with unique and aggressive characteristics is presented. PATIENT FINDINGS A 24-year-old athlete presented with a 3.5 cm left paramedian upper neck mass. Open biopsy demonstrated a papillary thyroid carcinoma arising in the pyramidal lobe. Additional imaging revealed involvement of her cricothyroid membrane, thyroid laryngeal cartilage, and left vocal cord. Complete en bloc surgical resection of the thyroid with cricothyroid membrane and endolarynx was performed with negative surgical margins. Microscopically, the tumor was largely solid with microfollicular architecture with focal cytoplasmic clearing and nodular invasion with rare true papillae, extending posteriorly through the cricothyroid membrane into the deep soft tissue of the left anterior vocal cord (pT4a). Metastases were present in 5/11 lateral neck and pretracheal lymph nodes with a size up to 0.4 cm (pN1b) with perinodal lymphatic involvement. She was staged according to her age (<45 years) as stage I. The solid-variant histology and locally aggressive behavior triggered oncologic genotyping, which was performed using massive parallel sequencing and anchored multiplexed next-generation sequencing for gene fusion detection on formalin-fixed paraffin embedded tissue. Targeted genotyping did not reveal a panel-specific point mutation. However, gene fusion assessment demonstrated a gene fusion involving ROS1. Mapping of the fusion and sequence analysis identified CCDC30 as the ROS1 fusion partner. Sequence-based prediction of the fusion product revealed the coiled-coil domain 30 (CCDC30) gene fused to the N-terminal ROS1 kinase domain, with CCDC30 as the postulated driver of ROS1-kinase constitutive activation. ROS1 rearrangement was confirmed using fluorescent in situ hybridization as an orthogonal method. A review of all currently reported ROS1 fusions in >7000 samples (The Cancer Genome Atlas) showed no prior report of ROS1-CCDC30, ROS1 fusions, or presence of ROS1 aberrations in thyroid cancer. SUMMARY Herein, the first case of a ROS1 rearrangement in a papillary thyroid carcinoma with a locally aggressive presentation is reported. CONCLUSION A review of additional patients with solid-variant papillary thyroid carcinoma and similar clinical characteristics with undetermined tumor genetics is needed, especially in light of the availability of ROS1-targeted therapeutics.

Effect of energy-based devices on voice quality after total thyroidectomy

Voice alteration is an important complication of thyroid surgery and is closely related to patients’ quality of life. There are no studies analyzing effect of energy-based devices (EBD) on voice quality (VQ). Aim of this prospective study is to evaluate impact of sutureless total thyroidectomy performed with EBDs on objective voice parameters of patients without recurrent laryngeal nerve (RLN) and/or external branch of superior laryngeal nerve (EBSLN) injury. Sixty patients underwent total thyroidectomy with meticulous dissection of EBSLN. Patients were assigned to Group L (Ligasure™), Group H (Harmonic), or Group C (Conventional) through random ballot. For analysis of alteration in VQ, digital videolaryngostroboscopy (VLS), voice handicap index (VHI), multidimensional voice program (MDVP), and electroglottography (EGG) were used. VLS was performed by 70°-angled indirect laryngoscopy and evaluation was standardized by VLS scale and laryngeal function scoring. This study is registered on clinicaltrials.gov with number NCT01865006. Forty eight patients were female. There was no difference on demographic data. On post-operative laryngoscopic examination, none of the patients had vocal fold palsy. When mean VHI scores at post-operative 1st week and 2nd month were compared to pre-operative values for each groups, groups L and H demonstrated a significant increase in VHI in the early post-operative evaluation, while there was no significant increase for group C. No significant increase was seen in late post-operative period compared to pre-operative period for any groups. In the early post-operative period, VQ is better with the conventional technique than EBDs; however, in late post-operative period, VQ is detected better in EBDs (especially in Group L) than the conventional technique, but no statistical difference was observed.

IONM of the Recurrent Laryngeal Nerve

Thyroid surgery can pose risk to both the right and the left recurrent laryngeal nerves (RLN) in a single surgical procedure. Unilateral vocal cord palsy (VCP) can lead to morbidity related to changes in voice, especially in professional voice users, as well as potential dysphagia and aspiration, while bilateral VCP may require tracheostomy. Visualization of the RLN during surgery has been considered the gold standard for preventing injury to the RLN; however, an intraoperatively visualized and structurally intact nerve does not necessarily represent a postoperatively functioning nerve. Neural monitoring has increasingly gained the attention of surgeons performing thyroid and parathyroid surgeries around the world. Current studies suggest that a majority of general and head and neck surgeons use neural monitoring in at least some of their thyroid surgical cases. This chapter presents a historical overview and usage patterns of intraoperative neural monitoring (IONM) of the RLN and discusses its impact on surgical practice, including intraoperative applications of IONM, medicolegal aspects and standards of IONM, normative data, as well as current advances in IONM such as continuous IONM.

Intraoperative Neural Injury Management: Transection and Segmental Defects

Patients who have undergone a transection or segmental resection of the recurrent laryngeal nerve (RLN) suffer from hoarseness, reduced phonation time, and aspiration. These injuries can be repaired with a direct anastomosis of the transected nerve ends, free nerve grafting to fill the defect, or an ansa cervicalis-to-RLN anastomosis. Reports have indicated that following nerve reconstruction, patients’ voices typically improve, although the vocal cords remain immobile through misdirected regeneration. Despite this, reinnervated vocal cords demonstrate less muscular atrophy. Voice recovery can be obtained regardless of preoperative vocal cord status, age, or gender when nerve reconstruction is performed with a variety of reconstruction modality techniques.

Monitoring of the posterior cricoarytenoid muscle represents another option for neural monitoring during thyroid surgery: Normative vagal and recurrent laryngeal nerve posterior cricoarytenoid muscle electromyographic data

Intraoperative neural monitoring (IONM) of laryngeal nerves using electromyography (EMG) is routinely performed using endotracheal tube surface electrodes adjacent to the vocalis muscles. Other laryngeal muscles such as the posterior cricoarytenoid muscle (PCA) are indirectly monitored. The PCA may be directly and reliably monitored through an electrode placed in the postcricoid region. Herein, we describe the method and normative data for IONM using PCA EMG.

Surgical management of the recurrent laryngeal nerve in thyroidectomy: American Head and Neck Society Consensus Statement

“I have noticed in operations of this kind, which I have seen performed by others upon the living, and in a number of excisions, which I have myself performed on the dead body, that most of the difficulty in the separation of the tumor has occurred in the region of these ligaments…. This difficulty, I believe, to be a very frequent source of that accident, which so commonly occurs in removal of goiter, I mean division of the recurrent laryngeal nerve.” Sir James Berry (1887)

Evaluation of neural cochlear structures after noise trauma using x-ray tomography

According to the World Health Organization (WHO), in 2010 hearing loss affected more than 278 million people worldwide. The loss of hearing and communication has significant consequences on the emotional well-being of each affected individual. The estimated socio-economic impact is about