Thyroid Dissection Research Articles

Fluorescence imaging to visualize the recurrent laryngeal nerve during thyroidectomy procedures: analysis of 65 cases and 81 nerves.

Recurrent laryngeal nerve (RLN) injury after thyroidectomy is relatively common. Locating the RLN prior to thyroid dissection is paramount to avoid injury. We developed a fluorescence imaging system that permits nerve autofluorescence. We aimed to determine the sensitivity and specificity of fluorescence imaging at detecting theRLN relative to thyroid and other background tissue and compared it to white light. In this prospective study, 65 patients underwent thyroidectomy from January to April 2022 (16 bilateral thyroid resections) using white and fluorescent light. Fluorescence intensity [relative fluorescence units (RFU)] was recorded for RLN, thyroid, and background. RFU mean, minimum, and maximum values were calculated using Image J software. Thirty randomly selected pairs of white and fluorescent light images were independently reviewed by two examiners to compare RLN detection rate, number of branches, and length and minimum width of nerves visualized. Parametric and nonparametric statistical analysis was performed. All 81 RNLs observed were visualized more clearly under fluorescence (mean intensity, µ = 134.3 RFU) than either thyroid (µ = 33.7, p < 0.001) or background (µ = 14.4, p < 0.001). Forest plots revealed no overlap between RLN intensity and that of either other tissue. Sensitivity and specificity for RLN were 100%. All 30 RLNs and all 45 nerve branches were clearly visualized under fluorescence, versus 17 and 22, respectively, with white light (both p < 0.001). Visible nerve length was 2.5 × as great with fluorescence as with white light (µ = 1.90 vs. 0.76cm, p < 0.001). In 65 patients and 81 nerves, RLN detection was markedly and consistently enhanced with autofluorescence neuro-imaging during thyroidectomy, with 100% sensitivity and specificity.

Anatomical relations of the recurrent laryngeal nerve in thyroid dissection

Introduction: Recurrent laryngeal nerve (RLN) palsy is one of the major complications thyroidectomy. Visualization of the anatomical relations of the RLN with branches of the inferior thyroid artery (ITA) remains essential for preservation of RLNs. Suspensory ligament of Berry, inferior horn of the thyroid cartilage is considered as other important landmarks for safe thyroidectomy. The objective of this study was to describe the various anatomical relations of the RLN during thyroid dissection.Methods: An observation cadaveric study was conducted by simple random sampling of 35 cadavers with a total of 70 RLNs over a one-year period, from June 2022 to June 2023. The cadavers that had thyroidotomies and goitres were excluded from the study.Results: The majority of RLNs in this series had a retrovascular course (with respect to the ITA or its branches): 57% on the right and 68.6% on the left. The course of 64/70 of the dissected nerves was posteromedial to the suspensory ligament of Berry, while the other 6 nerves passed between the fibres of this ligament. All RLNs penetrated the larynx by passing posteriorly to the inferior horn of the thyroid cartilage on both sides. No case of non-recurrent laryngeal nerve was observed.Conclusion: This preliminary study illustrates the numerous anatomical variants of the RLN with respect to the ITA and its branches. The RLN mainly has a retrovascular course on both the right and the left sides.

TOETVA parathyroid autofluorescence detection: hANDY-i endoscopy attachment.

Treatment options for thyroid pathologies have expanded to include scarless and remote access methods such as the transoral endoscopic thyroidectomy vestibular approach (TOETVA). Currently, no standardized methods exist for locating parathyroid glands (PGs) in patients undergoing TOETVA, which can lead to parathyroid injury and subsequent hypocalcemia. This early feasibility study describes and evaluates the hANDY-i endoscopic attachment for detecting PGs in transoral thyroidectomy. We used a prototype parathyroid autofluorescence imager (hANDY-i) that was mounted to a 10-mm 0-degree endoscope. The device delivers a split screen view of Red-green-blue (RGB) and near-infrared autofluorescence (NIRAF) which allows for simultaneous anatomical localization and fluorescence visualization of PGs during endoscopic thyroid dissection. One cadaveric case and two patient cases were included in this study. The endoscopic hANDY-i imaging system successfully visualized PGs during all procedures. The ability to leverage parathyroid autofluorescence during TOETVA may lead to improved PG localization and preservation. Further human studies are needed to assess its effect on postoperative hypocalcemia and hypoparathyroidism.

The TOFr of 0.75 to 0.85 is the optimal timing for IONM during thyroid surgery: a prospective observational cohort study

BackgroudRecurrent laryngeal nerve (RLN) injury is one of the serious complications of thyroid tumour surgery, surgical treatment of thyroid cancer requires careful consideration of the RLN and its impact on glottis function. There has been no unified standard for precise neuromuscular block monitoring to guide the monitoring of RLN in thyroid surgery. This study aimed to investigate the correlation between Train-of-four stabilization ratio (TOFr) and neural signal values of intraoperative neurophysiological monitoring (INOM) during thyroid operation, and further to determine the optimal timing for INOM during thyroid operation.MethodsPatients scheduled for thyroid tumour resection with INOM and RLN monitoring from April 2018 to July 2018 in our center were recruited. Electromyography (EMG) signals and corresponding TOFr were collected. All nerve stimulation data were included in group VR. Vagus nerve stimulation data were included in Subgroup V. RLN stimulation data were included in Subgroup R. The timing of recording was as follows: Vagus nerve EMG amplitude after opening the lateral space between the thyroid and carotid sheath and before the initiation of thyroid dissection, RLN EMG amplitude at first recognition, RLN EMG amplitude after complete thyroid dissection (Repeat three times), and Vagus nerve EMG amplitude after resection of the thyroid (Repeat three times). Correlation analysis of continuous variables was described by a scatter diagram. Pearson correlation analysis or Spearman correlation analysis was used for the two groups of variables.ResultsFinally, 134 vagus nerve signals and 143 RLN signals were analysed after matching with TOFr. The EMG amplitude in the VR group and subgroups after nerve stimulation was positively correlated with TOFr (p < 0.05). In the VR, V and R group, the incidence of EMG ≥ 500 µV in the 0.75 < TOFr ≤ 0.85 interval was significantly higher than the 0 < TOFr ≤ 0.75 interval (P = 0.002, P = 0.013 and P = 0.029), and has no statistical difference compared to 0.85 < TOFr ≤ 0.95 interval (P > 0.05).ConclusionsThe EMG signals of the RLN and vagus nerve stimulation during thyroid surgery were positively correlated with TOFr. TOFr > 0.75 could reflect more than 50% of the effective nerve electrophysiological signals, 0.75 < TOFr ≤ 0.85 interval was the optimal timing for IONM during thyroid surgery.Trial registrationChinese Clinical Trial Registry (ChiCTR1800015797) Registered on 20/04/2018. https://www.chictr.org.cn.

Administration of neostigmine after tracheal intubation shortens time to successful intraoperative neuromonitoring during thyroid surgery: a randomized controlled trial

This prospective, randomized controlled trial evaluated the effect of neostigmine for intraoperative neuromonitoring (IONM) during thyroid surgery. Forty subjects undergoing thyroidectomy with IONM, randomized into neostigmine administration after tracheal intubation (Group N, n = 20) or control treatment with normal saline (Group C, n = 20), completed the trial. Electromyography amplitudes of the vagus nerve (V1) were recorded before thyroid dissection. The time from the initial V1 signal check to successful V1 stimulation was recorded. In Group N, all the patients had a successful V1 signal at the first check, whereas ten (50%) patients in Group C had a time delay between the initial V1 check and successful V1 (p < 0.001). The mean delay time among the delayed patients in Group C was 11.2 ± 1.4 min. The mean time from skin incision to successful V1 stimulation was significantly shorter in Group N than in Group C (15.4 ± 2.4 min vs. 19.9 ± 5.7 min, p = 0.003). In Groups N and C, the mean V1 amplitudes were 962.2 ± 434.5 μV vs. 802.3 ± 382.7 μV (p = 0.225), respectively, and the mean R1 amplitudes were 1240.0 ± 836.5 μV vs. 1023.4 ± 455.8 μV (p = 0.316), respectively. There was one bucking event in Group N. In conclusion, neostigmine administration immediately after tracheal intubation can be useful to reverse neuromuscular blockade for successful IONM in thyroid surgeries.

Is the indocyanine green score an accurate predictor of postoperative parathyroid hormone level?

BackgroundHypoparathyroidism is common after total thyroidectomy, primarily due to inadvertent disruption of the parathyroid gland blood supply during thyroid dissection. Indocyanine green helps determine the degree of vascularization and correlates with parathyroid gland vitality. It is difficult to determine how the indocyanine green score affects postoperative parathyroid hormone levels because all 4 parathyroid glands must be evaluated during surgery. We determined whether there is a correlation between intraoperative indocyanine green score and postoperative serum parathyroid hormone levels. MethodsWe retrospectively studied patients who underwent total thyroidectomy where we could identify all 4 parathyroid glands and establish a global indocyanine green score. Each parathyroid gland was scored from 0 to 2 depending on indocyanine green uptake. The global indocyanine green score was the sum of the individual scores for each gland. The scores were then correlated to parathyroid hormone and calcium levels on days 1 and 10 after surgery. ResultsWe included 83 patients, 11 of whom presented with postoperative transient hypoparathyroidism; all but one had an indocyanine green score lower than 4 of 8. There was a significant correlation between the global indocyanine green score and postoperative parathyroid hormone level. A global indocyanine green score >3.75 can exclude postoperative hypoparathyroidism with a true negative value of 98%. Indocyanine green angiography is a better diagnostic test to predict a postoperative transient hypoparathyroidism compared with visual perfusion scoring. ConclusionThese findings suggest that the indocyanine green score based on intraoperative indocyanine green angiography predicts parathyroid gland function. It is a valuable instrument to predict hypoparathyroidism after total thyroidectomy.

Low-Dose of Rocuronium During Thyroid Surgery: Effects on Intraoperative Nerve-Monitoring and Intubation

BackgroundIntraoperative Neurophysiological Monitoring (IONM) reduces the incidence of Recurrent Laryngeal Nerve (RLN) injuries during thyroid surgery. To preserve nerve function, long acting neuromuscular blocking agents (NMBA) should be avoided. However, NMBA are necessary for laryngoscopy and endotracheal intubation. We designed this double-blinded, randomized, placebo-controlled trial to assess if a low-dose of rocuronium given at intubation would affect the IONM data recorded before the thyroid dissection. MethodsHundred patients undergoing elective thyroid surgery were randomized to receive either 0.3 mg kg−1 of low dose rocuronium (intervention) or no-NMBA (control). Intubation was performed with video-laryngoscopy. IONM was placed on RLN and nerve stimulation was performed before and after thyroid dissection. The presence of a valid amplitude prior to dissection was defined when the IONM signal was >100 μV. Occurrence of difficult laryngoscopy was reported together with intubation details including time, difficulty and failure. The lowest peripheral saturation (SpO2) and the number of desaturation episodes during the intubation were also registered. ResultsNo patients showed impaired IONM signal before dissection in both groups. Cormack-Lehane grade was higher in the intervention group (11;2) compared to control one (11;1; P = 0.046). No-NMBA patients had increased number of difficult laryngoscopies (21% versus 6%, P = 0.041) and intubations (34% versus 8%; P = 0.003) as well as a longer time to intubation (78 [55; 175] versus 55 [31; 110] sec; P = 0.006). Lower values of peripheral SpO2 during intubation attempt were registered in the no NMBA group (99 [97; 100] versus 99 [99; 100] %; P = 0.020). However, the number of intubation failure was similar between groups (p=0.495). ConclusionsLow-dose of rocuronium does not compromise pre-dissection IONM signal and improves intubation condition when compared to a relaxant free strategy.

English

BACKGROUND From the last century to modern days, there has been a paradigm shift in the field of thyroid surgery. Initially what was a dreadful surgery with multi fold serious complications, now with the advent of modern surgical technique (bipolar to nerve monitoring &amp; emerging use of microscope), and better knowledge of anatomy, it has become one of the most frequently performed surgeries worldwide with very few complications. In spite of all these, postoperative complications like recurrent laryngeal nerve (RLN) palsy is still mostly feared by surgeons and still is one of the most frequent complications. METHODS This was a prospective nonrandomised controlled trial conducted among 60 study participants in the Department of Otorhinolaryngology and Head &amp; Neck Surgery, of a tertiary care centre in West Bengal from July 2016 to June 2018. In this study two different surgical techniques were applied in two patient groups. In one group subcapsular dissection of thyroid gland was done without exploration of recurrent laryngeal nerve course in neck; and in another group, the complete course of the aforesaid nerve in the neck was explored and preserved. The postoperative functional status of RLN was assessed by fibreoptic laryngoscopy immediately after recovery from anaesthesia and in postoperative follow ups. We wanted to compare the outcome (in terms of functional status of RLN) in these two groups. RESULTS 3 patients (10 % cases) of nerve palsy were seen among 30 patients of subcapsular dissection group, whereas only one case (3.3 %) of nerve palsy was seen amongst 30 cases of complete exploration of recurrent laryngeal nerve. CONCLUSIONS Thyroidectomy with meticulous exploration of the recurrent laryngeal nerve was found to be a superior method as compared to the subcapsular dissection. KEYWORDS Recurrent Laryngeal Nerve, Subcapsular Dissection, Complete Exploration, Thyroidectomy

Warning criterion to predict recurrent laryngeal nerve injury with percentage reduction of the amplitude of V2/R2d in neuromonitoring thyroidectomy

ObjectiveTo evaluate the contribution of amplitude reduction compared vagal stimulation at the end of thyroid dissection (V2) to the most distal RLN stimulation during thyroidectomy in predicting postoperative vocal cords paralysis (VCP). MethodsPatients with intact preoperative RLN function who underwent monitored thyroidectomy between August 2017 and April 2018 were included. We routinely tested the exposed RLN at the lowest proximal end (R2p signal) and the most distal end near the laryngeal entry point (R2d signal), and then routinely detected the vagal nerve at the horizontal plane of the inferior pole of thyroid with 2mA stimulation current. The cut-off value was calculated with Receiver Operating Characteristic curve. Rates of specificity, sensitivity, negative predictive value, positive predictive value (PPV) for V2/R2d and R2p/R2d were compared. ResultsPercentage reduction of the amplitude of V2/R2d ranged from 34.8% to 76.7%. Twenty-two (1.5%) nerves developed temporary VCP, in which one nerve with VCP showed no significant amplitude reduction at the end of the surgery. There was no permanent or bilateral VCP. Sensitivity, specificity, PPV, NPV, and accuracy for the amplitude reduction of V2/R2d> 60% were 95.5%, 99.8%, 99.9%, 98.2%, respectively, for R2p/R2d were 99.5%, 99.2%, 63.6%, 99.9%, 97.7%, respectively. ConclusionPercentage reduction of the amplitude of V2/R2d is a reliable and practical warning criterion for RLN injury. When the amplitude reduction> 60% surgeons should consider the possibility of postoperative VCP and correct some surgical maneuvers.

Relevant Anatomy for the Transoral Vestibular Approach to the Thyroid and Parathyroid Glands

This paper highlights the key anatomical considerations for the surgeon to appreciate in order to carry out a safe and effective transoral vestibular approach to the central neck for thyroid and parathyroid dissection. The transoral, vestibular approach for thyroidectomy and parathyroidectomy avoids external, visible scarring altogether. This approach requires additional understanding of intraoral and cervical anatomy from an altered viewpoint compared with open central neck surgery as the surgeon creates a working space from the mouth to the neck and views the thyroid and parathyroid glands from a superior to-inferior position.

Randomized Controlled Trial Comparing White Light with Near-Infrared Autofluorescence for Parathyroid Gland Identification During Total Thyroidectomy

Parathyroid glands are difficult to identify during total thyroidectomies, and accidental resection can lead to problematic postoperative hypocalcemia. Our main goals were to evaluate the effectiveness of using near-infrared light (NIRL) autofluorescence intraoperatively for parathyroid gland identification and to measure its impact on postoperative hypocalcemia incidence. Total thyroidectomies were performed on 170 patients with different thyroid pathologies, block-randomized (1:1) into 2 equal groups. Among controls, traditional overhead white light (WL) was used throughout. In the experimental group, NIRL was used to enhance parathyroid gland recognition before thyroid dissection. The number of parathyroid glands identified was compared after thyroid dissection in controls using WL vs pre-dissection in the experimental using NIRL and with WL vs NIRL before thyroid dissection in the experimental group. Postoperative serum calcium levels and hypocalcemia rates were compared. The mean number of parathyroid glands identified pre-dissection with NIRL was the same identified post-dissection with WL (3.5 vs 3.6). In the experimental group, converting from WL to NIRL increased the number of glands detected from 2.6 to 3.5 (p < 0.001), and revealed at least 1 previously missed gland in 67.1% of patients. Calcium levels ≤7.5 mg/dL were one-tenth as common in the NIRL group (p= 0.005). The adjusted odds of hypocalcemia developing increased by 15% for every 5-g increase in thyroid gland weight (odds ratio 1.15; 95% CI 1.06 to 1.25). All hypocalcemia resolved within 6 months. Using NIRL during thyroidectomy increases intraoperative identification of parathyroid glands, enhances their detection before thyroid dissection, and decreases the incidence of postoperative hypocalcemia.

Safety and Efficacy of Bipolar Radiofrequency Ablation Device in Hemostasis during Thyroidectomy in Comparison with Ultrasonic Scalpel: A Comparative Study.

Aim:Ultrasonic scalpel is one of the recent advances in surgical technology. The main limitation of their use is the cost. However, radiofrequency ablation device is a refined type of electrosurgical cautery that can be used with conventional reusable bipolar cautery forceps. This study aims to compare the efficacy of bipolar radiofrequency ablation device that can be used with conventional reusable bipolar cautery forceps for hemostasis and dissection during thyroidectomy with that of ultrasonic scalpel.Materials and Methods:Sixty patients underwent total thyroidectomy were recruited at Alshiffa General Hospital, Basrah, Iraq from March 2016 to June 2017. The participants were divided into two equal groups: in the first group thyroid dissection was done with ultrasonic scalpel, and in the second group thyroid dissection was done with bipolar radiofrequency ablation device. Outcome and complications of both procedures were analyzed statistically and compared.Results:The bipolar radiofrequency ablation device significantly reduced the mean operative time by (−15.35 min) in comparison to ultrasonic scalpel. The Bipolar Radiofrequency Ablation Device (BRFA) group reported a mean operative time of 50.13 ± 14.16 compared to 65.49 ± 7.78 in the US group with, P value = 0.001. There was no statistically significant difference in the other outcome parameters and the rate of complications reported between the two devices during this study.Conclusion:The bipolar radiofrequency ablation device that can be used with conventional reusable bipolar cautery forceps is a simple, safe, and time-saving adjunct for thyroid surgeries and equally effective as compared to costly instruments like ultrasonic scalpel.Clinical Significance:The bipolar radiofrequency device can be used in thyroid surgery to secure hemostasis, save time, and cost.

Combined Total Thyroidectomy and Coronary Artery Bypass Grafting: An Endocrine Surgeon Perspective

When thyroid enlargement and coronary artery disease occur together, both are not necessarily operated at the same time. Nevertheless, combined thyroidectomy and coronary arterial bypass grafting (CABG) have been reported to be feasible and safe. The decisions on whether to do the operations concurrently and how exactly the operations should be performed were not clearly explained. We present a case of coronary artery disease which complicated with presence of multinodular goitre. We explain how we performed the combined thyroidectomy and CABG and provide relevant important points pertaining to the operations. In conclusion, when combining thyroidectomy and cardiac bypass surgery, performing thyroid dissection before heparinization and thus CABG, could be a wiser decision as it associated with less bleeding in the neck wound and has a better chance of avoiding complications related to the thyroidectomy.

Transaxillary single-port subtotal parathyroidectomy: feasibility study in cadavers.

to test the minimally invasive technique of single-port transaxillary subtotal parathyroidectomy in non-formalized cadavers to evaluate its viability and reproduction. we performed ten subtotal parathyroidectomies through a transaxillary TriPort access in cadavers. The technique consisted of access through the axillary fossa, creating a subcutaneous tunnel to the anterior cervical region, for handling of the thyroid gland and dissection and resection of the parathyroid glands. all surgeries were successful. The mean time of surgery was 65 minutes (57-79 min), with uncomplicated identification of all anatomical structures. There was no need for complementary incisions in the cervical region. the transaxillary single-port subtotal parathyroidectomy technique was feasible and reproducible, suggesting an alternative for minimally invasive cervical surgery.

Percutaneous probe stimulation for intraoperative neuromonitoring in total endoscopic thyroidectomy: A preliminary experience

The purpose of this study was to investigate the feasibility and value of using intraoperative neuromonitoring (IONM) performed via percutaneous probe stimulation during total endoscopic thyroidectomy. This study prospectively enrolled a series of 132 consecutive patients with 156 recurrent laryngeal nerves (RLNs) at risk who received total endoscopic thyroidectomy performed via bilateral breast approach using standardized IONM. The stimulation probe was introduced into the working space by percutaneous puncture. During lateral thyroid dissection, the proximal RLN was periodically stimulated to monitor adverse electromyography (EMG) changes. Preoperative and postoperative vocal cord mobility was routinely examined with laryngofiberoscopy. All IONMs were successfully performed via percutaneous probe stimulation with no morbidity or scarring in the neck. Twelve nerves (7.7%) showed significant changes in EMG (amplitude reduction, 50% to 90% from baseline EMG) during the lateral thyroid dissection. Compression near the inferior thyroid artery (70%) and traction near the Berry's ligament (30%) were the most common causative mechanisms, and modification of the surgical maneuver resulted in partial recovery of the EMG changes (amplitude reduction, 10% to 80% before wound closure). Of the 12 nerves with adverse EMG changes (final amplitude reduction, 65% to 80%), 8 nerves showed temporary (3 months or less) vocal cord palsy. No cases of permanent vocal cord palsy occurred in this series. Percutaneous probe stimulation is a simple, effective, and safe method of performing IONM in total endoscopic thyroidectomy when the operating space is limited. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1001-1007, 2017.

Voice Changes after Late Recurrent Laryngeal Nerve Identification Thyroidectomy

To assess voice changes in patients after thyroidectomy where the recurrent laryngeal nerve (RLN) was found late in the thyroid dissection and where the RLN was not injured (late RLN identification technique). This study was conducted on 64 patients who underwent thyroidectomy by late RLN identification technique. Voice was assessed preoperatively, 1 week, 3 months, and 6 months after surgery using the voice assessment protocol and Voice Problem Self-Assessment Scale. The study group was divided into two subgroups (hemithyroidectomy: N = 13 and total thyroidectomy: N = 51). Voice assessments of both subgroups were then compared with a control group (N = 20) of patients who recently underwent extracervical surgeries. All voice analysis differences between the control group and the individual study subgroup were nonsignificant. Dysphonia in the study group was significantly worse at 1 week and 3 months postoperatively but became nonsignificant at 6 months postoperatively. The deviations from the preoperative acoustic analysis were significant only in the first week postoperative comparison for fundamental frequency, noise-to-harmonic ratio, and maximal phonation time and thereafter became nonsignificant. Significant Voice Problem Self-Assessment Scale mean score increase (worsening) was also detected only at first week postoperatively. Minimal voice changes were reported early after late RLN identification thyroidectomy in absence of RLN injury and disappeared gradually in a few months. Those changes are comparable with that of other extracervical surgeries, making thyroidectomy with late RLN identification a relatively safe technique as regard voice.

Implications of Anatomical and Morphological Variations of Thyroid Gland: A Case Report

Because of extreme variations in gross Anatomy of Thyroid Gland, Marshal stated that it was a difficult work to speak about normal thyroid gland [1]. Description of incidence of Pyramidal lobe, an embryological remnant of thyroglossal duct differ from 15 to 75% in Anatomical text books and data concerning its size are lacking [2, 3]. During the routine undergraduate dissection of Thyroid gland for Ist year MBBS in the Department of Anatomy, Govt. Medical college, Amritsar, India, in an elderly Male cadaver various morphological anomalies of Thyroid gland were encountered. These were in the form of presence of pyramidal lobe on left side, tip of which was attached to hyoid bone through Levator glandulae thyroidae and absence of superior thyroid artery on right side. The knowledge of various Anatomical & Morphological variation will help surgeons in forming a cornerstone to safe and effective surgeries.

Signalveränderungen des kontinuierlichen intraoperativen Neuromonitorings bei Schilddrüseneingriffen mit postoperativen Rekurrensparesen

Continuous intraoperative neuro-monitoring (kontIONM) and the provision of relevant information such as moment, origin and prognosis of nerve function impairment during thyroid resection have been tested. Between 2009 and 2011, 667 patients were operated for thyroid pathology by applying kontIONM (tube electrode, vagal probe V3, ISIS; Fa. Inomed, Emmendingen, Germany). Vocal cord function was examined laryngoscopically on the 2nd postoperative day. Palsies were diagnosed in 34 patients. Complete kontIONM signals were filed during the operation. Loss of signal (LOS), defined as amplitude reduction < 100 µV, and signal delay > 10% were attributed to thyroid dissection. A LOS of 17.6% (6/34) developed already at the moment of thyroid lobe luxation, that is, prior to a dissection for recurrent laryngeal nerve (NLR) identification. An LOS of 67.6% (23/34) appeared during NLR preparation in the vicinity of the Berry ligament. Thus, 85.3% of all vocal cord palsies were recognised intraoperatively. For four patients signal delay > 10% could be observed in the analysis of the postoperative signal but not during the operation. One case was not associated with any of these signal changes. In the majority of cases, signal loss and reduction of amplitude < 100 µV are reliable parameters of post-operative vocal cord palsy. Traction and distension of the nerve seems to be the most important cause of nerve damage. An immediate revision of the last step of the surgical procedure, if required, is the essential advantage of this method to avoid irreversible nerve damage. For a minor part of the cases, vocal cord palsies are characterised intraoperatively by an extended delay of the signal.

Endoscopic Thyroidectomy with Miniature Tools in a Pig Model

Objective: Assess the feasibility of direct endoscopic thyroidectomy in a porcine model using CO2 pneumodissection, miniature cameras and endoscopic tools. Method: The study was conducted during the second half of 2011. Endoscopic thyroid dissection was performed in a porcine model with CO2 pneumodissection, using cameras and endoscopic tools ranging in diameter between 2 and 5 mm. Results: Thyroid dissection was performed in a total of 10 pigs. Two were “open” procedures to learn the porcine anatomy. Eight were endoscopic procedures. Of them 5 used three 5-mm incisions and 3 used three 2- to 3-mm incisions for surgical tools and a 5-mm incision for the endoscopic camera. In all cases the thyroid was completely dissected with the recurrent laryngeal nerve (RLN) identified and preserved. In 5 cases the thyroid was removed through the floor of the mouth. There was no major bleeding in the live pigs, and all the vital structures were identified and preserved. Conclusion: Endoscopic thyroidectomy using miniature camera and tools in a porcine model seems to be feasible without major complications. The advantages of this approach include minimal scars and improved visualization. We believe that there is room for further development of minimal invasive techniques for thyroid surgery.

The Impact of Intraoperative Neuromonitoring (IONM) on Surgical Strategy in Bilateral Thyroid Diseases: Is it Worth the Effort?

Intraoperative nerve monitoring (IONM) of the recurrent laryngeal nerve and the vagal nerve can detect nonfunctioning nerves (recurrent laryngeal nerve palsy, RLNP) that are visibly intact. The use of IONM is questionable, however, as we still lack evidence that it reduces the rate of postoperative nerve injuries. Since negative IONM results after thyroid dissection of the first side could change our surgical strategy and thus could prevent patients from bilateral RLNP, we questioned whether IONM results are reliable enough to base changes in surgical strategy and whether this has any effect on surgical outcome. We retrospectively analyzed the data of 1333 consecutive patients with suggested benign bilateral thyroid disease who had been operated on under a defined protocol, including the use of a specific IONM technique (tube electrodes and stimulation of the vagal nerve and the inferior recurrent nerve before and after thyroid resection), between January 1, 2006 and December 31, 2008. In four patients the IONM system did not work, two nerves had not been found, and in eight patients the tube had to be readjusted. Of five permanent nerve injuries, four were visible during surgery and one was suspected. Sensitivity of IONM in detecting temporary nerve injuries of macroscopically normal-appearing nerves was 93%. Specificity was 75-83% at first side of dissection and 55-67% at the second side, with an overall specificity of 77%. In 11 of 13 patients (85%) with known nerve injury (preexisting or visible) and in 20 of 36 patients (56%) with negative IONM stimulation at the first side of dissection, the surgical strategy was changed (specific surgeon or restricted resection) with no postoperative bilateral RLNP. This was in contrast to 3 of 18 (17%) bilateral RLNP (p < 0.05), when surgeons were not aware of a preexisting or highly likely nerve injury at the first side of thyroid dissection. Failed IONM stimulation of the vagal or recurrent laryngeal nerve after resection of the first thyroid lobe is specific enough to reconsider the surgical strategy in patients with bilateral thyroid disease to surely prevent bilateral RLNP.