Intraoperative Neuromonitoring Research Articles

The Use of Intraoperative Neuromonitoring for Cervical Spine Surgery: Indications, Challenges, and Advances.

Intraoperative neuromonitoring (IONM) has become an indispensable surgical adjunct in cervical spine procedures to minimize surgical complications. Understanding the historical development of IONM, indications for use, associated pitfalls, and recent developments will allow the surgeon to better utilize this important technology. While IONM has shown great promise in procedures for cervical deformity, intradural tumors, or myelopathy, routine use in all cervical spine cases with moderate pathology remains controversial. Pitfalls that need to be addressed include human error, a lack of efficient communication, variable alarm warning criteria, and a non-standardized checklist protocol. As the techniques associated with IONM technology become more robust moving forward, IONM emerges as a crucial solution to updating patient safety protocols.

Evaluation of intraoperative neuromonitoring (IONM) data with the Mainz IONM Quality Assurance and Analysis tool

Abstract Background Intraoperative neuromonitoring is widely used in thyroid and parathyroid surgery to prevent unilateral and especially bilateral recurrent nerve paresis. Reference values for amplitude and latency for the recurrent laryngeal nerve and vagus nerve have been published. However, data quality measures that exclude errors of the underlying intraoperative neuromonitoring (IONM) data (immanent software errors, false data labelling) before statistical analysis have not yet been implemented. Methods The authors developed an easy-to-use application (the Mainz IONM Quality Assurance and Analysis tool) using the programming language R. This tool allows visualization, automated and manual correction, and statistical analysis of complete raw data sets (electromyogram signals of all stimulations) from intermittent and continuous neuromonitoring in thyroid and parathyroid surgery. The Mainz IONM Quality Assurance and Analysis tool was used to evaluate IONM data generated and exported from ‘C2’ and ‘C2 Xplore’ neuromonitoring devices (inomed Medizintechnik GmbH) after surgery. For the first time, reference values for latency and amplitude were calculated based on ‘cleaned’ IONM data. Results Intraoperative neuromonitoring data files of 1935 patients consecutively operated on from June 2014 to May 2020 were included. Of 1921 readable files, 34 were excluded for missing data labelling. Automated plausibility checks revealed: less than 3 per cent device errors for electromyogram signal detection; 1138 files (approximately 60 per cent) contained potential labelling errors or inconsistencies necessitating manual review; and 915 files (48.5 per cent) were indeed erroneous. Mean(s.d.) reference onset latencies for the left vagus nerve, right vagus nerve, recurrent laryngeal nerve, and external branch of the superior laryngeal nerve were 6.8(1.1), 4.2(0.8), 2.5(1.1), and 2.1(0.5) ms, respectively. Conclusion Due to high error frequencies, IONM data should undergo in-depth review and multi-step cleaning processes before analysis to standardize scientific reporting. Device software calculates latencies differently; therefore reference values are device-specific (latency) and/or set-up-specific (amplitude). Novel C2-specific reference values for latency and amplitude deviate considerably from published values.

Is There a Role for Intraoperative Neuromonitoring in Intradural Extramedullary Spine Tumors? Results and Indications from an Institutional Series.

While intraoperative neurophysiological monitoring (IONM) is considered a standard for intramedullary spinal cord tumor surgery, the effective role of IONM in intradural extramedullary (IDEM) tumors is still debated. We present the results of 60 patients affected by IDEM tumors undergoing surgery with the aid of IONM. Each patient was evaluated according to the modified McCormick scale (MMS) at admission, discharge and at follow-up. During surgery, motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs) were studied using the Medtronic NIM-eclipse® 32-channel system (Medtronic Xomed, Inc. 6743 Southpoint Drive North Jacksonville FL USA). Patients' age, gender and tumor location did not affect MMS modifications. Tumors involving more than three levels had an increased likelihood of MMS worsening, while meningioma pathology was associated with worse preoperative and 1-year follow-up MMS. No MEP amplitude ratio was able to predict clinical variations, while intraoperative SEP worsening was associated with 100% risk of poor MMS at discharge and with 50% risk of poor MMS at long-term follow-up. In our opinion, SEP monitoring is a valid tool that may contribute to the preservation of the patient's neurological status. MEP monitoring is not mandatory in IDEM surgery while more studies are required to explore the feasibility and the role of D-wave in this kind of surgery.

Comparison of intraoperative neural monitoring between endoscopic transoral and bilateral axillo-breast approach thyroidectomy.

The use of intraoperative neuromonitoring (IONM) during endoscopic thyroidectomy has not been fully explored, with limited studies focusing solely on the recurrent laryngeal nerve (RLN) and neglecting the external branch of the superior laryngeal nerve (EBSLN). This study aimed to compare the effectiveness of IONM in two endoscopic thyroidectomy techniques, namely the transoral and bilateral axillo-breast approach (BABA). We retrospectively reviewed patients who underwent endoscopic thyroidectomy with IONM and compared the outcomes between those who underwent different surgical techniques (transoral or BABA). We recorded the detection method and identification rate of the EBSLN and RLN, along with the amplitude and latency of the evoked potential. We monitored 98 nerves at risk (NAR) from 74 patients (60 and 38 in the transoral and BABA groups, respectively). Almost all EBSLNs were identified using electromyography (EMG) signals and/or cricothyroid muscle twitches, except for one patient in the transoral group who developed EBSLN palsy. Patients in the transoral group were more likely to have the sternothyroid muscle divided (75.0% vs. 15.8%, p < 0.001) and had a lower rate of visual recognition of the EBSLN fibers (10.0% vs. 31.6%, p = 0.007) than did those in the BABA group. All RLNs were identified in both groups; however, patients in the BABA group had a relatively higher rate of post-dissection amplitude reduction > 50% (15.8% vs. 5.0%, p = 0.072), and one patient had transient RLN palsy. Both the EBSLN and RLN could be adequately identified and monitored during endoscopic transoral and BABA thyroidectomies using IONM.

Utilization of pre-operative MRI to identify AIS patients at highest risk of intra-operative neuromonitoring alert.

Utility of pre-operative MRI for patients undergoing scoliosis correction has expanded to include an MRI classification for identifying patients at increased risk of experiencing intra-operative neuromonitoring (IONM) alerts based on the shape of the spinal cord and circumferential presence of CSF at the apex of the thoracic curve. In the present study, the authors explore the utility of this new MRI classification and multiple X-ray radiographic parameters in identifying the AIS sub-population at high risk of IONM alerts. AIS patients < 18years old who underwent posterior spinal fusion between 2018 and 2022 at a single institution. Imaging reviewed to determine main thoracic (MT) and thoraco-lumbar (TL) Cobb angles, major thoracic Apical Vertebral Translation (AVT) and lumbar/thoraco-lumbar AVT (TL AVT), thoracic kyphosis (TK), coronal main thoracic Deformity Angular Ratio (cDAR), sagittal DAR (sDAR), and MRI to determine the spinal cord type (1, 2, or 3). A total of 155 AIS patients who met the inclusion criteria between 2018 and 2022 were included. There was a trend to have an increased incidence of Type 3 spinal cord shape both with increase in the MT Cobb angle and MT AVT. There was also a shift toward more IONM alerts in patients with Type 3 (19.5%) spinal cords, AVT ≥ 5cm (18.9%), and Cobb angle ≥ 650 (28.2%). Higher magnitude of thoracic Cobb angle and AVT are associated with higher likelihood of type 3 spinal cord at the apex in MRI. Patients with Type 3 spinal cord, Cobb angle ≥ 650, AVT > 5cm, and cDAR > 10 have higher likelihood to have IONM alerts. Patient with a Type 3 spinal cord and a Cobb angle ≥ 650 (50.0%), cDAR > 10 (43.7%), and AVT > 5cm (35.2%) have the highest risk of having IONM alerts.

Bilateral vision loss as first presentation of vestibular schwannoma

Abstract Vestibular schwannoma is a benign, slow-growing tumor of the vestibular nerve, located at cerebellopontine angle. It is derived from the Schwann cells of the myelin sheath of cranial nerve eight. We present here a unique case of vestibular schwannoma, who visited us with a primary complaint of bilateral decreased vision. Detailed examination revealed bilateral papilloedema associated with right-sided cranial nerve five and eight involvements. Patient was operated for the right-sided cerebellopontine angle tumor under intraoperative neuromonitoring. Postoperatively, patient showed significant improvement, both symptomatically and clinically.

Thoracoscopic Anterior Vertebral Body Tethering in Lenke Type-1 Right Adolescent Idiopathic Scoliosis.

Vertebral body tethering (VBT) is indicated for skeletally immature patients with progressive adolescent idiopathic scoliosis (AIS) who have failed or are intolerant of bracing and who have a major coronal curve of 40° to 65°. The vertebral body must be structurally and dimensionally adequate to accommodate screw fixation, as determined radiographically. The best indication for VBT is a flexible single major thoracic curve with nonstructural compensating lumbar and proximal thoracic curves (Lenke 1A or 1B). VBT allows for progressive correction of the deformity without spinal fusion by utilizing a minimally invasive fluoroscopic technique. The procedure for a right thoracic curve is performed with use of a right thoracoscopic approach with the patient in the left lateral decubitus position. The thoracoscope is introduced through a portal at the apex of the curvature in the posterior axillary line. Instrument portals are created lateral to each vertebral body in the mid-axillary line. Screws are inserted into each vertebral body under biplanar fluoroscopic control and with intraoperative neuromonitoring. An electroconductivity probing device, while not mandatory, is routinely utilized at our practice. The tether is attached to the most proximal screw of the construct, and then reduction is obtained sequentially by tensioning the tether from one vertebral screw to the next. Bracing is the gold-standard treatment for progressive AIS involving the immature spine. The most commonly utilized surgical treatment is posterior spinal fusion (PSF), which should be considered when the major coronal curve exceeds 45°. PSF has proven to be a dependable technique to correct scoliotic deformities. It has a low complication rate and good long-term outcomes. However, concerns exist regarding the stiffness conferred by PSF and the long-term effects of adjacent segment disease. Thus, interest had developed in non-fusion solutions for AIS correction. VBT utilizes the Hueter-Volkmann principle to guide growth and correct deformity. Compressive forces applied to the convexity of the deformity by a polyethylene tether allow the patient's growth to realign the spine. Intraoperative correction triggers growth modulation, and most of the modulation seems to occur during the first 12 months postoperatively. The best results have been seen with a short Lenke type-1A curve in a patient with closed triradiate cartilage, a Risser 3 or lower (ideally Risser 0) iliac apophysis, and a flexible curve characterized by a 50% reduction of the major coronal curve angle on side-bending radiographs. In 57 immature patients with a Lenke type-1A or 1B curve (i.e., a 30° to 65° preoperative Cobb angle), Samdani et al.3 found a main thoracic Cobb angle reduction from 40° ± 7° preoperatively to 19° ± 13° at 2 years after VBT. In the sagittal plane, the T5-T12 kyphosis measured 15° ± 10° preoperatively, 17° ± 10° postoperatively, and 20° ± 13° at 2 years. No major neurologic or pulmonary complications occurred. A total of 7 (12.3%) of the 57 patients underwent surgical revision, including 5 for overcorrection and 2 to span additional vertebrae. In a study of 21 skeletally mature patients, Pehlivanoglu et al.4 found that the Cobb angle was reduced from 48° preoperatively to 16° on the first-erect postoperative radiograph and finally to 10° at the latest follow-up (mean, 27.4 months). The 2 main complications of VBT reported in the literature are overcorrection and tether breakage. Both may require revision, which explains the higher rate of revision observed for VBT compared with PSF. Good patient selection is important. VBT is most appropriate in cases of a flexible Lenke type-1A or 1B curve in an immature child before Risser stage 3 and after triradiate cartilage closure.Always monitor and control screw positioning in both anteroposterior and lateral planes fluoroscopically.The screws should be placed parallel to the vertebral end plates or, even better, be angled inferiorly for the upper vertebrae and angled superiorly for the lower vertebrae to decrease the risk of pull-out when tensioning the device and during growth modulation. Less tension on the uppermost and lowermost instrumented vertebrae than at the apex, as controlled by the tensioning device, can also help to limit pull-out. VBT = vertebral body tetheringAIS = adolescent idiopathic scoliosisIONM = intraoperative neuromonitoringPSF = posterior spinal fusionUIV = upper instrumented vertebraLIV = lower instrumented vertebraAP = anteroposteriorK-wire = Kirschner wire.

The role of intraoperative neuromonitoring of facial nerve in microsurgical excision of vestibular schwannomas

Abstract Background Preserving the function of facial nerve (FN) is an important objective of cerebellopontine angle tumor excision. FN paresis and paralysis possibly happen postoperatively, in particular for vestibular schwannoma (VS) excision, despite efforts to prevent injury and preserve anatomic integrity of the FN during dissection. Aim Evaluation of the role of neuromonitoring of FN in microsurgical resection of VSs and its impact on FN function preservation and quality of life. Patients and methods This trial was conducted on 22 patients with VS in the period from February 2018 to February 2020. All patients had undergone VS microsurgical excision in the Neurosurgery Department, Tanta University Hospitals. Results According to House-Brackmann grading scale, the functions of FN postoperatively were grade I in 16 patients (72.6%), grade III in three patients (13.6%), grade IV in two patients (9%), and grade V in one patient (4.7%). So, House-Brackmann grading scale II to VI means preservation less than 100%, which was achieved in six patients (27.3%). Conclusion Intraoperative neurophysiologic monitoring plays an essential step in modern skull base surgery generally and in VS surgery specifically. FN electromyography does not only help localize and identify the anatomy of FN but as well keep FN integrity of function and can be helpful in the prediction of its postoperative functional outcome.

Utility of the continuous intraoperative neuromonitoring in the prevention of the recurrent laryngeal nerve paralysis during thyroid surgery. A prospective observational study

BackgroundThe continuous intraoperative neuromonitoring (C-IONM) of the recurrent laryngeal nerve (RLN) could help reducing the incidence of nerve paralysis after thyroid surgery, in comparison with the mere anatomical visualization of the RLN. The objective is to assess the efficacy and utility of C-IONM as a predictive test for recurrent laryngeal nerve paralysis after thyroidectomy. MethodsA prospective observational study was performed in 248 patients who underwent thyroid surgery where C-IONM was applied, between September 2018 and December 2019, in a high-volume center. A previous and later laryngoscopy was performed, which allowed to evaluate the reliability of the C-IONM as a predictive test for recurrent paralysis. Sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV) were studied. ResultsA total number of 171 thyroidectomies, 62 hemithyroidectomies, 15 totalization thyroidectomies and 27 thyroidectomy with cervical dissections were performed. Postoperative laryngoscopy was altered in 40 patients (16.12%). The SE, SP, PPV and NPV values ​​were 65%, 94.7%, 70.2% and 93.4% respectively. ConclusionsC-IONM is a safe technique that provides real-time information about anatomical and functional integrity of the RLN and can improve the results of thyroid surgery.

Letter: Two Practices to Improve Informed Consent for Intraoperative Brain Research.

To the Editor: We read with great enthusiasm the paper by Peabody et al1 discussing the challenges of the informed consent for clinical research in the context of intraoperative brain research. This is a crucial ethical challenge requiring deep reflexion in the current environment within the neurosurgical practice. The authors highlight the heterogeneous impact and retention of the information provided during the consent process as well the unique place occupied by the relational dimension between the surgeon and the patient during this process. They suggest the involvement of a patient's advocate and reconsent during awake craniotomy (if applied) to overcome some of the abovementioned limitations. At our center, we have established a dedicated neuro-oncology preoperative assessment clinic for discussing the diagnosis and the treatment plan with both patients and their relatives.2 We strongly agree that patient's relatives should be involved in the decision-making process from very early stages to support the patient to take the best informed decisions for himself. The introduction to potential research programs is performed by the responsible neurosurgeon although the research consent process is independent and performed by the research team. Nevertheless, the responsible neurosurgeon is at the center of the consent process given the personalized relational dimension outlined by Peabody et al1 and unique relationship between the surgeon and the patient, particularly in the setting of the awake craniotomy. A point that is worthwhile mentioning is how the research-derived information can help the clinical consent process. At our institution, we performed extensive preoperative mapping that is explained to the patients as part of their consent process.3,4 This significantly improves their understanding about the procedure, particularly the benefits and risks involved.5 Therefore, there is an active interaction between the clinical and research consent processes. Although they are independent in their nature, the information provided by one can facilitate the understanding of the other and promote a more informed decision and potential involvement in both treatment and research processes. Patient information for patients with cancer is a vital part to personalized informed consent6 and forms a national measure to hold UK oncology centers accountable. According to the National Cancer Patient Experience Survey in the United Kingdom,7 89.4% of patients, who underwent surgery for cancer, said that before their treatment started, they had the information they needed in a way they could understand. It demonstrated that although the experience was good, we still had more room for improvement and innovation in the way we educate patients and make them understand regarding their disease process. Different strategies have been used to improve the consent form process, such as personalized 2-dimensional and 3-dimensional imaging available during consent process8 which is aligned with the General Medical Council in UK recommendations in their principles of decision making and consent.9 Thus, pushing the boundaries with innovative technology that is patient friendly promoting positive patient experience would act as an important process in the armamentarium for the current and future neurosurgeons. The increase utilization10 and recent advances in intraoperative neuromonitoring and mapping paved the way to a better understanding of the mechanisms underlying the brain function. Despite being independent processes, clinical treatment and research have a dynamic interaction where the neurosurgical team has a pivotal role in integrating the information provided. We could not agree more that the patient is at the center of all the decisions made even at the time of surgery during awake procedures.1 The challenge to the surgical teams is to provide constantly updated information to allow the best decision-making process to the patients and their advocates before surgery and to the patient himself during the awake procedure.

Factors Affecting C5 Viability and Demographic Variability in Two Brachial Plexus Centers.

A retrospective study of 200 consecutive patients with complete brachial plexus injuries at two international centers (Mayo Clinic in the United States and Chang Gung Memorial Hospital in Taiwan) was performed. Demographic information, concomitant injuries, mechanism, and details of the injury were determined, and kinetic energy (KE) and Injury Severity Score were calculated. C5 nerve root was evaluated by preoperative imaging, intraoperative exploration, and/or intraoperative neuromonitoring. A spinal nerve was considered viable if it was grafted during surgery. Complete five-nerve root avulsions of the brachial plexus were present in 62% of US and 43% of Taiwanese patients, which was significantly different. Increasing age, the time from injury to surgery, weight, body mass index of patient, motor vehicle accident, KE, Injury Severity Score, and presence of vascular injury significantly increased the risk of C5 avulsion. Motorcycle (≤150cc) or bicycle accident decreased the risk of avulsion. Significant differences were found between demographic variables between the two institutions: age of injury, body mass index, time to surgery, vehicle type, speed of injury, KE, Injury Severity Score, and presence of vascular injury. The rate of complete avulsion injury was high in both centers. Although there are a number of demographic differences between the United States and Taiwan, overall the KE of the accident increased the risk of C5 avulsion.

ID: 208864 EMG Component and Use in Prediction for Target Engagement During Spinal Cord Stimulation

Dorsal column responses (DCR) recorded from spinal cord stimulation (SCS) leads represent a promising method of improving effectiveness of SCS. DCR may include evoked compound action potentials (ECAP), late response component and others. Late response component in the DCR has been demonstrated in intraoperative neuromonitoring (IONM) to represent the nearby muscle activation. Quantitative analysis between the ECAP and EMG components in DCR could reveal important information about target engagement. In this study, we intend to quantify the DCR with intermuscular EMG recordings to understand how to properly use the EMG components to better inform spinal cord stimulation.

Use of NMBA and reversal agent during thyroid surgery with intraoperative neuromonitoring

Neuromuscular blocking agent (NMBA) provides adequate muscle relaxation for intubation and surgery, but their use can interfere with the interpretation of intraoperative neuromonitoring (IONM) signals. Various strategies for the use of NMBA during thyroid surgery with IONM have been proposed for both safe anesthesia and surgery, and adequate quality of IONM. Relaxant-free anesthesia or use of succinylcholine is not recommended as a routine use due to the potential of fatal complications such as laryngeal injury or malignant. Instead, the use of a single dose of rocuronium for intubation with or without a reversal agent has been widely adapted. Though spontaneous recovery of neuromuscular blockade can be achieved without a reversal agent, use of a reversal agent can shorten the time for adequate IONM. Both neostigmine and Sugammadex can be used to reverse the neuromuscular blockade. Neostigmine reverses all types of non-depolarizing NMBA, but can accompany systemic cholinergic effect, and is not effective to deep or higher level of blockade. Sugammadex only reverses the effect of aminosteroid NMBAs, but effective to all levels of blockade. Overall, appropriate strategies for the use of NMBAs and reversal agents are needed to ensure effective IONM without increasing the risk of nerve injury during surgery.

갑상선 수술 중 신경모니터링의 훈련 프로그램 개발

Intraoperative neuromonitoring (IONM) for the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve during thyroidectomy may be helpful to identify and preserve the nerves and let the surgeon predict the postoperative neural function. International Neural Monitoring Study Group (INMSG) recently presented the recommended training course for IONM during thyroidectomy. Based on such training course provided by an expert group, trainees may conduct standardized IONM and experience the technique's advantages. This review article presents the recommended guidelines to prepare for a training course in IONM during thyroidectomy.

Application of total intravenous anesthesia (TIVA) during intraoperative neuromonitoring (IONM)

TIVA stands for Total Intravenous Anesthesia, which is a technique of general anesthesia (GA) giving all anesthetic drugs through an intravenous (IV) route. Intraoperative neuromonitoring (IONM) is a method of real-time evaluation of the functional integrity of neural structures used to prevent potential damage and allows to correlate surgical interventions with neurophysiological changes at a time when damage from surgical trauma can be avoided or reverted. TIVA confers many advantages over inhalational anesthesia with volatile agents and it is preferred in certain clinical cases including during IONM.

Anesthetic Management during Intraoperative Neuromonitoring

Anesthetic Management during Intraoperative Neuromonitoring

Intraoperative Neuromonitoring during Peripheral Arteriovenous Malformation Embolization

PurposeTo evaluate whether intraoperative neuromonitoring (IONM), including pre-embolization lidocaine injection challenge (“provocative testing”) is associated with reduced risk of irreversible nerve injury during embolization of peripheral arteriovenous malformations (AVMs). Materials and MethodsMedical records of patients with peripheral AVMs who underwent embolotherapy with IONM with provocative testing between 2012 and 2021 were reviewed retrospectively. Data collected included patient demographic characteristics, AVM location and size, embolic agent used, IONM signal changes after lidocaine and embolic agent injections, postprocedural adverse events, and clinical outcomes. Decisions regarding whether embolization would proceed at specific locations were based on IONM findings after the lidocaine challenge and as embolization proceeded. ResultsA cohort of 17 patients (mean age, 27 years ± 19; 5 women) who underwent 59 image-guided embolization procedures with adequate IONM data was identified. No permanent neurologic deficits occurred. Transient neurologic deficits were observed in 3 patients (4 sessions), comprising skin numbness (2 patients), extremity weakness (1 patient), and extremity weakness and numbness (1 patient). All neurologic deficits resolved by postoperative day 4 without additional treatment. ConclusionsIONM, including provocative testing, during AVM embolization may minimize potential nerve injury.

Neurophysiological monitoring during endovascular treatment of brain arteriovenous malformations: A meta-analysis.

Treatment of brain arteriovenous malformations (b-AVM) carries a risk of iatrogenic injury to eloquent brain regions. Intraoperative neuro-monitoring (IONM) has increasingly been used to monitor spontaneous or evoked neural activity during neurosurgery, but its use is not as well characterized in the endovascular treatment (EVT) of b-AVMs. We aimed to provide a systematic review and meta-analysis of studies reporting any neurological deficit after b-AVM embolization with IONM, with or without provocative test (PT), and no-IONM. This systematic review followed the PRISMA guidelines. Medline, EMBASE, and Scopus were searched from conception until March 1, 2022 for studies evaluating EVT with IONM and PT. Primary outcome was the rate of postoperative neurological deficits in EVT with IONM versus no-IONM, while secondary outcome was the subanalysis of IONM with or without PT. Meta-analysis was performed using the Mantel-Haenszel method and random effects modeling. Six studies reached synthesis. Out of a total of 192 EVT, 14 events occurred. Results demonstrated a nonsignificant trend favoring IONM compared to no-IONM to prevent neurological deficits (OR 0.09, 95% CI 0-4.68). Among the EVT with IONM, PT was done in 411 branches with 10 events (0.2%) despite a negative PT. There was a nonsignificant trend favoring IONM plus PT compared to IONM without PT (OR 0.16, 95% CI 0.02-1.07). Our study suggests that b-AVM EVT with IONM plus PT might reduce rates of postprocedural neurological deficits compared with EVT without IONM. Further studies are needed to confirm these results.

Treatment of Chiari Malformation and Concomitant Paediatric Scoliosis Long-Term Follow-Up in One Major Referral Centre in the UK.

Paediatric scoliosis (PS) and Chiari malformation type 1 (CM-1) have been reported to be associated with each other. Scoliosis curvature is a common finding among patients operated for CM-1, and curve development has been related to it. We report a cohort of PS and CM-1 patients managed with posterior fossa and upper cervical decompression (PFUCD) by a single surgeon, with an average of two years of follow-up. We present a retrospective cohort in a single referral centre for patients with CM-1 and PS. From 2011 to 2018, we identified fifteen patients with CM-1 and PS; eleven underwent PFUCD, ten had symptomatic CM-1, and one had asymptomatic CM-1 but showed curve progression. The remaining four CM-1 patients were asymptomatic and were hence treated conservatively. The average follow-up post-PFUCD was 26.2 months. Scoliosis surgery was performed in seven cases; six patients underwent PFUCD prior to the scoliosis correction. One scoliosis case underwent surgery in the presence of mild CM-1 treated conservatively. The remaining four cases were scheduled for scoliosis correction surgery, while three were managed conservatively, with one case lost to follow-up. The average time between PFUCD and scoliosis surgery was 11 months. None of the cases had intraoperative neuromonitoring alerts or perioperative neurological complications. CM-1 with concomitant scoliosis can be found. Symptomatic CM-1 might require surgery, but as we discovered, PFUCD had negligible effect on curve progression and the future need for scoliosis surgery.

Variant anatomy of non-recurrent laryngeal nerve: when and how should it be taught in surgical residency?

While the performance of a thyroidectomy is generally associated with a low risk of injury to the recurrent laryngeal nerve (RLN), the presence of a non-recurrent nerve (NRLN) increases the risk of this complication. Generally, the intraoperative detection via visual appreciation of variant anatomy of the RLN has been regarded as poor, possibly due to a lack of knowledge of both the normal and aberrant anatomy of the RLN. Articles for the review were searched through PubMed using the search terms and their combinations: "non-recurrent laryngeal nerve," "thyroidectomy," "injury," "palsy," "variant anatomy," and "residency," from January 1, 2000, to December 2022. Papers considered for the review were the articles published in English, with additional classic and articles of surgical importance retrieved from the reference list of papers. Only papers relevant to the scope of the review were considered for this review. The NRLN has been found to be associated with concurrent vascular abnormalities, such as the presence of an aberrant right subclavian artery (ARSA) or an arteria lusoria originating from the aortic arch. However, it seems that both the normal as well as aberrant anatomy of the RLN is currently not emphasized enough during postgraduate surgical training. With the increased use of intraoperative neuromonitoring (IONM), detection of NRLN has become possible through appropriate neural mapping during thyroid surgery, besides other pointers such as visualization during surgery, computerised tomography, and duplex ultrasound scans to visualize the variant vascular anatomy. There is also a possible role for cadaveric courses, either during medical school or in a post-graduate setting-adapted to the student's level to teach the variant anatomy. With the development of newer techniques such as artificial intelligence, there are potential new options for teaching and training anatomy in the near future. Adequate knowledge of the normal and aberrant anatomy of the RLN remains essential for the best outcomes in thyroid surgery, even in the era of the IONM. Moving forward, the knowledge of (aberrant) anatomy should be made an integral part of the core competencies of both medical students and surgical trainees. It is imperative that leaders of the different field work closely together to combine their knowledge towards providing their trainees with the best possible training options.