Sensitivity and Specificity of Intraoperative Recurrent Laryngeal Nerve Stimulation in Predicting Postoperative Nerve Paralysis

Abstract

Bilateral recurrent laryngeal nerve (RLN) paralysis after thyroidectomy is infrequent, but serious when it occurs. Intraoperative knowledge of the status of the nerve after dissection could potentially provide the surgeon with important decision-making information. The current study examines the sensitivity and specificity of intraoperative stimulation of the RLN during thyroid surgery for predicting postoperative RLN deficits. Eighty-one RLNs in 55 patients were identified to be at risk of injury during thyroidectomy or parathyroidectomy performed between January 1998 and February 2000. Intraoperative determination of RLN function was evaluated with a disposable nerve stimulator (Xomed, Jacksonville, Florida) set at 0.5 mA. Injury was assessed by palpating for a contraction of the posterior cricoarytenoid muscle while the stimulus was applied. Postoperative assessment of RLN integrity was determined by using indirect or direct laryngoscopy to visualize vocal fold mobility. Nine RLNs failed to elicit a posterior cricoarytenoid contraction after nerve stimulation, and 4 RLNs were determined to be deficient in the postoperative evaluation. The calculated sensitivity and specificity were 75% and 92.2% with a positive predictive value of 33.3% and negative predictive value of 98.6%. The RLN injury rate was 4.94%. We conclude that intraoperative RLN stimulation is a relatively safe and useful method of determining what RLN function will be after thyroid or parathyroid surgery.

General and regional anaesthesia for the thyroidectomy in rural/semi-urban Nigerian centres

“…More importantly, advocates of voice monitoring as against nerve monitoring under anaesthesia are increasing daily (1,9). The applicability of these techniques is in conformity with the practice and principle of surgery which is based on safety, efficacy, cost effectiveness and patients' satisfaction (16,24).…”

“…Bed space conservation was an added advantage as 26 (30%) of the group II patients were treated as day cases. In terms of voice monitoring, this was possible with RA group as the patients were awake and could converse with the surgeons and swallow salivary secretions (16)(17)(18)(19)(20)(21). Though, direct laryngoscopic examination were carried out at extubation on the group I patients, direct voice monitoring could not be done until six to 24 hours post operatively.…”

“…Further, considering the consequences of laryngeal nerve and other nerve injuries post thyroidectomy, intra-operative monitoring becomes imperative. However, workers are now advocating voice monitoring which is possible under regional anaesthesia (2) as preferable to nerve monitoring under general anaesthesia (3,(16)(17)(18)(19)(20)(21). To the best of our knowledge, all the earlier works on this subject were done in advanced and well equipped centres.…”

Intraoperative cranial nerve monitoring

“…Contraction of the vocalis muscle in response to electrical stimulation can also be confirmed visually with fiberoptic laryngoscopy. The published data on laryngeal muscle monitoring clearly demonstrate that the techniques are reliable and help to identify the external and recurrent branches of the laryngeal nerves, 16,37,38,74 but only one study has attempted to determine whether monitoring reduces the risk of laryngeal nerve injury. 92 Thomusch et al 92 prospectively surveyed 4,382 patients undergoing surgery for benign goiter at 45 hospitals in Germany.…”

A method of securing the Xomed endotracheal tube for accurate monitoring of the recurrent laryngeal nerve

“…For some surgeons, this monitoring represents the White arrows indicate two of the existing 4 wires of the Xomed tube surface electrodes exposed above the cuff, which come into direct contact with the mucosa of the vocal cords. standard of care during surgery of the brainstem, skull base, thyroid, and parathyroid glands [1][2][3][4].…”