Intraoperative Neuromonitoring Techniques Research Articles

갑상선 및 부갑상선 수술 중 신경 모니터링에 대한 가이드라인과 표준 술식

The benefits of intraoperative neuromonitoring (IONM) extend beyond merely reducing the incidence of vocal cord paralysis. Although widely used, a review of various literatures and clinical studies indicates diverse applications of nerve monitoring. To advance and standardize IONM techniques, the International Neural Monitoring Study Group (INMSG) has published guidelines for monitoring the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN). While IONM effectively preserves RLN function, application methods vary among surgeons. Implementing standardized setups and guidelines can reduce vocal cord paralysis and facilitate appropriate decisions when loss of signal (LOS) occurs, thereby ensuring the best outcomes for patients. This review aims to synthesize the current INMSG guidelines and summarize standard procedures for RLN monitoring.

Stereoscopic Monitoring Technique for Motor Area Tumors

The balance between comprehensive intraoperative neurophysiological monitoring (IONM) for both upper and lower limbs while ensuring the reliability of motor evoked potentials (MEPs) is paramount in motor area surgery. It is commonly difficult to obtain good simultaneous stimulation of both upper and lower limbs. A series of factors can bias MEP accuracy, and inappropriate stimulation intensity can result in unreliable monitoring. The presented IONM technique is based on the concurrent use of both transcranial and cortical strip electrodes to facilitate simultaneous monitoring of both upper and lower limbs at optimized stimulation intensities to increase IONM accuracy during motor area surgery. Ten nonconsecutive motor area tumors were studied. Good visualization of both limbs was observed in the series at a low amperage (1.2 mA from thestrip electrode and 165.3 mA from the transcranial electrode). Our analysis confirms concordance between the IONM data and postoperative outcomes. An MEP reduction >20% and >50% correlated with postoperative modified Rankin scale score changes without false-negative IONM findings. The technique was demonstrated to be accurate in providing a good simultaneous neurophysiological evaluation of both upper and lower limbs with an optimized and stimulation amplitude. The technique results in a low encumbrance of electrodes in the surgical field. Our results have confirmed the "proof of concept," its reliability and feasibility.

갑상선 수술중 신경모니터링의 최근 연구

Thyroid surgery is associated with a risk of injury to the recurrent laryngeal nerve(RLN), the external branch of the superior laryngeal nerve(EBSLN), and voice changes. Intraoperative neuromonitoring(IONM) has already gained universal reliability to help in nerve identification, safe nerve dissection, and prediction of postoperative vocal cord function. IONM techniques have evolved over the past decade into intermittent IONM(I-IONM) and continuous IONM(C-IONM) modes of application. Research in the field of IONM continues, exploring new techniques and approaches to further enhance the safety and efficacy of thyroid surgery. In this article, the role of IONM and its recent studies will be reviewed.

Utility of Decremental Triggered Electromyogram for Intraoperative Neuromonitoring to Identify Midline in Posterior Myelotomy for Spinal Cord Intramedullary Lesions: Technical Note of a Novel Method.

Intramedullary spinal cord lesions are eloquent lesions that are surgically resected via posterior midline myelotomy (PMM). This treatment method carries the risk of postoperative neurological deficits. Various intraoperative neuromonitoring techniques have been used to address this concern. Our study aimed to highlight a newly developed monitoring technique (decremental-triggered electromyogram [dtEMG]) as a novel method to identify the spinal cord midline during PMM. Seven patients in prone position underwent PMM for an intramedullary lesion using dtEMG for neuromonitoring. dtEMG was used to determine the threshold amplitude (ie, the lowest amplitude to elicit an EMG response) as well as a silent zone, which was determined to be the midline. The age range was 26-73 years. dtEMG detected a silent zone in 6/7 patients. The only patient in whom dtEMG was not useful was a patient with complete paraplegia and sensory loss before surgery. There were no motor evoked or somatosensory evoked potential changes related to PMM in these patients. Although the commonly used neuromonitoring techniques, including motor and sensory evoked potentials and free-run electromyograms are of utmost importance in spinal cord surgery, they lack the potential to identify midline in such cases. The currently available tools, including dorsal column mapping, are more cumbersome to use. The newly proposed dtEMG technique can safely and efficiently identify the midline when used as an intraoperative neuromonitoring technique in PMM for spinal cord intramedullary lesion resection.

Chinese guidelines on intraoperative neuromonitoring in thyroid and parathyroid surgery (2023 edition).

As an auxiliary tool, intraoperative neuromonitoring (IONM) has played an active role in the protection of nerve function in thyroid and parathyroid surgeries. This study aimed to help clinicians understand, standardize and reasonably apply IONM techniques in laryngeal nerves function protecting. Hundreds of Chinese experts in the field of IONM participated in this work. All efforts have been made to ensure that these new guidelines are practical, systematic, and based on well-recognized cutting-edge evidence. Using the three previous guidelines as well as new preclinical and clinical evidence from China and other countries, the expert panel summarized the current accepted or near-accepted opinions as the recommendations. In addition, the recommendation grades and evidence levels are presented in accordance with the Grading of Recommendations Assessment, Development and Evaluation (GRADE). The first draft was completed by the writing team and then revised after several rounds of discussions via email or meetings. The finalized version of this guideline includes 42 recommendations, which may inform and guide our peers in their clinical practice, including all types of open, endoscopic, and robotic thyroid and parathyroid surgeries. This edition is currently the most comprehensive, and clinically significant guide for IONM of thyroid and parathyroid surgery in China.

Diagnostic Accuracy of Somatosensory Evoked Potential monitoring during Scoliosis correction surgery in the pediatric population: A Systematic Review (P7-4.002)

<h3>Objective:</h3> To evaluate the diagnostic accuracy of intraoperative somatosensory evoked potential (SSEP) monitoring in predicting the risk of perioperative neurological outcomes during scoliosis fusion surgery for idiopathic scoliosis (IS) in the pediatric age group (≤ 21 years). <h3>Background:</h3> Scoliosis correction surgery is the most effective treatment for pediatric IS. However, new neurological deficits during the surgery can potentially affect the outcomes of this surgery. Intraoperative neuromonitoring techniques like SSEP provide real-time information about the spinal cord and nerve roots and can be used as a reliable indicator to predict perioperative neurological deficits. <h3>Design/Methods:</h3> A systematic review of various databases to find literature on pediatric IS patients who underwent scoliosis correction with intraoperative neuromonitoring. Data collection included study design, patient demographics, procedure, neuromonitoring modalities, SSEP alarm criteria, SSEP changes (including reversible and irreversible changes), and perioperative neurological deficit. We calculated the sensitivity, specificity, and diagnostic odds ratio (DOR) of SSEP changes (total, transient, and persistent) and SSEP loss for predicting perioperative neurological deficits. <h3>Results:</h3> We included eighteen studies for our final analysis, with a total cohort of 4674 children. The incidence of a significant SSEP change was 3.1% (145/4674), while the incidence of a new neurological deficit was 1.01% (47/4674). The incidence of new neurological deficits in children with an intraoperative SSEP change was 28.28% (41/145), while it was 0.13% (6/4529) in children without an SSEP change. SSEP changes had a sensitivity of 72%, specificity of 97%, and DOR of 98.64, while SSEP loss had a sensitivity of 42%, specificity of 99.3%, and a DOR of 143.76 for predicting new neurologic deficit. Transient and Persistent SSEP changes had sensitivities of 37% and 39%, specificities of 97% and 99.2%, and DORs of 18.09 and 75.43, respectively. <h3>Conclusions:</h3> Intraoperative SSEP monitoring can predict perioperative neurological injury and help improve the surgical outcomes in pediatric scoliosis fusion surgery. <b>Disclosure:</b> Dr. Gorijala has nothing to disclose. Dr. Shaik has nothing to disclose. The institution of Dr. Thirumala has received research support from University of Pittsburgh. Dr. Anetakis has nothing to disclose. Jeffery Balzer has nothing to disclose. Donald Crammond has nothing to disclose. Dr. Shandal has nothing to disclose. Dr. Lee has nothing to disclose. The institution of Dr. Shaw has received research support from LSRS. The institution of Dr. Shaw has received research support from CSRS. The institution of Dr. Shaw has received research support from AO Spine. Dr. Shaw has received intellectual property interests from a discovery or technology relating to health care. Mr. Reddy has nothing to disclose.

Intraoperative Triggered Electromyography for Pedicle Screw Placement Under Spinal Anesthesia: A Preliminary Report.

Triggered electromyography (tEMG) is an intraoperative neuromonitoring technique used to assess pedicle screw placement during instrumented fusion procedures. Although spinal anesthesia is a safe alternative to general anesthesia in patients undergoing lumbar fusion, its use may potentially block conduction of triggered action potentials or may require higher threshold currents to elicit myotomal responses when using tEMG. Given the broad utilization of tEMG for confirmation of pedicle screw placement, adoption of spinal anesthesia may be hindered by limited studies of its use alongside tEMG. To investigate whether spinal anesthesia affects the efficacy of tEMG, we compare the baseline spinal nerve thresholds during lumbar fusion procedures under general vs spinal anesthesia. Twenty-three consecutive patients (12 general and 11 spinal) undergoing single-level transforaminal lumbar interbody fusion were included in the study. Baseline nerve threshold was determined through direct stimulation of the spinal nerve using tEMG. Baseline spinal nerve threshold did not differ between the general and spinal anesthesia cohorts (3.25 ± 1.14 vs 3.64 ± 2.16 mA, respectively; P = .949). General and spinal anesthesia cohorts did not differ by age, body mass index, American Society of Anesthesiologists score status, or surgical indication. We report that tEMG for pedicle screw placement can be safely and effectively used in procedures under spinal anesthesia. The baseline nerve threshold required to illicit a myotomal response did not differ between patients under general or spinal anesthesia. This preliminary finding suggests that spinal anesthetic blockade does not contraindicate the use of tEMG for neuromonitoring during pedicle screw placement.

When the intra-operative neuro-monitoring techniques crossed swords with the electro-encephalogram monitoring!

When the intra-operative neuro-monitoring techniques crossed swords with the electro-encephalogram monitoring!

O107 / #726 MIDLINE ISOLATION AND NEUROMONITORING WITH HIGH-DENSITY MICROELECTRODE ARRAYS FROM THE SURFACE OF THE SPINAL CORD: TRACK 4: CARDIOVASCULAR DISORDERS / NEURAL ENGINEERING

Intraoperative neuromonitoring (IONM) reduces the risk for postoperative neurological dysfunction during spinal cord surgery (1–4). Common IONM techniques do not record directly from the spinal cord, but instead rely on indirect measures, including evoked motor and sensory potentials. However, the exposed cord provides an untapped potential for direct assessment of function and pathology. Direct recordings from the spinal cord could lower the amount of stimulation required to capture responses and allow for continual monitoring (5–7). Here, we present results from human spinal cord recordings using highly conformable microelectrode arrays with high-density spatial coverage. Future clinical application of this technology would include treatment of spinal cord injury (SCI) and chronic pain.

Intraoperative neuromonitoring of the recurrent laryngeal nerve is indispensable during complete endoscopic radical resection of thyroid cancer: A retrospective study.

ObjectiveComplete endoscopic radical resection of thyroid cancer, especially through the areolar approach, can achieve curative and acceptable cosmetic effects in patients with differentiated thyroid carcinoma. However, some inherent characteristics of endoscopic procedures hamper functional protection of the recurrent laryngeal nerve (RLN). Intraoperative neuromonitoring (IONM) is considered the most important accessory to protect the nerves during conventional radical thyroidectomy. This study aimed to evaluate the feasibility and necessity of IONM during complete endoscopic radical resection of thyroid cancer.MethodsA total of 106 patients with differentiated thyroid carcinoma were enrolled in the study between February 2013 and April 2018. Based on the use of the IONM technique, all patients were divided into the IONM (n = 54) and non‐IONM groups (n = 52). Overall, 66 RLNs were involved in the IONM group, and 61 RLNs were involved in the non‐IONM group. The time and ratio of RLN identification and the number of transient and permanent RLN injuries between both groups were compared.ResultsCompared to the non‐IONM group, the IONM group required less time for RLN identification (3.05 ± 1.58 vs. 9.36 ± 4.82 min, p < .01). The ratio of RLN identification in the IONM group was much higher than that in the non‐IONM group (100.00% vs. 88.52%, p = .01). A significant difference was observed in RLN transient injury between the two groups (one case accounting for 1.51% in the IONM group vs. eight cases accounting for 13.11% in the non‐IONM group; p = .03).ConclusionIONM significantly improved RLN identification and reduced transient RLN injuries during complete endoscopic radical resection.Level of Evidence3b.

Direct brainstem somatosensory evoked potentials for cavernous malformations.

Brainstem cavernous malformations (CMs) often require resection due to their aggressive natural history causing hemorrhage and progressive neurological deficits. The authors report a novel intraoperative neuromonitoring technique of direct brainstem somatosensory evoked potentials (SSEPs) for functional mapping intended to help guide surgery and subsequently prevent and minimize postoperative sensory deficits. Between 2013 and 2019 at the Stanford University Hospital, intraoperative direct brainstem stimulation of primary somatosensory pathways was attempted in 11 patients with CMs. Stimulation identified nucleus fasciculus, nucleus cuneatus, medial lemniscus, or safe corridors for incisions. SSEPs were recorded from standard scalp subdermal electrodes. Stimulation intensities required to evoke potentials ranged from 0.3 to 3.0 mA or V. There were a total of 1 midbrain, 6 pontine, and 4 medullary CMs-all with surrounding hemorrhage. In 7/11 cases, brainstem SSEPs were recorded and reproducible. In cases 1 and 11, peripheral median nerve and posterior tibial nerve stimulations did not produce reliable SSEPs but direct brainstem stimulation did. In 4/11 cases, stimulation around the areas of hemosiderin did not evoke reliable SSEPs. The direct brainstem SSEP technique allowed the surgeon to find safe corridors to incise the brainstem and resect the lesions. Direct stimulation of brainstem sensory structures with successful recording of scalp SSEPs is feasible at low stimulation intensities. This innovative technique can help the neurosurgeon clarify distorted anatomy, identify safer incision sites from which to evacuate clots and CMs, and may help reduce postoperative neurological deficits. The technique needs further refinement, but could potentially be useful to map other brainstem lesions.

Intraoperative Corticobulbar Motor Evoked Potential in Cerebellopontine Angle Surgery: A Clinically Meaningful Tool to Predict Early and Late Facial Nerve Recovery.

Intraoperative neuromonitoring is crucial for facial nerve preservation in cerebellopontine angle (CPA) surgery. Among the available techniques, the role of intraoperative corticobulbar facial motor evoked potentials (FMEPs) is unclear. To evaluate the significance of intraoperative FMEPs as indicators for early and late postoperative facial nerve function (FNF) in CPA tumor resection and the feasibility of their integration with standard monitoring techniques. An institutional series of 83 patients who underwent surgery under intraoperative monitoring for CPA extra-axial tumor resection was reported. A pair of needle electrodes was used to record FMEP from orbicularis oculi (OOc) and orbicularis oris (OOr) muscles at baseline, at the end of surgery and minimum values recorded. From FMEP amplitudes, minimum-to-baseline amplitude ratio (MBR), final-to-baseline amplitude ratio (FBR), and recovery value, intended as FBR minus MBR, were calculated. These indices were correlated with early and late postoperative FNF. Our analysis demonstrated that higher FBR (both from OOc and OOr) and MBR (from OOr only) were associated with a good early and late FNF; a higher MBR from OOc was significantly associated with a good late FNF. The most accurate index in predicting early FNF was FBR measured from OOr with a cutoff of 35.56%, whereas the most accurate index in predicting late FNF was FBR as measured from OOc with a cutoff of 14.29%. Our study confirmed that FMEPs are reliable predictors of early and late postoperative FNF in CPA surgery and could be easily integrated with standard intraoperative neuromonitoring techniques.

The Predictive Value of Multimodal Intraoperative Neuromonitoring Techniques for Periprocedural Preventive Interventions during Carotid Surgery (P15-10.006)

The Predictive Value of Multimodal Intraoperative Neuromonitoring Techniques for Periprocedural Preventive Interventions during Carotid Surgery (P15-10.006)

Intraoperative Neuromonitoring for Skull Base Surgery

Intraoperative neuromonitoring techniques can be used to evaluate neural functions during surgical procedures. For removal of tumors in the skull base region, we perform them for both structural mapping of the compressed cranial nerves and continuous monitoring of their preservation. The goal is to eliminate the critical irreversible damage to the neurological structures and prevent postoperative neurologic deficits. Recording techniques have been developed and neuromonitoring equipment used in the operation room with the intravenous anesthesia technique. For skull base surgery, in particular, the neuromonitoring contains motor evoked potential(MEP), brainstem auditory evoked potential(BAEP), visual evoked potential(VEP), and others. We believe that the appropriate recording and interpretation of these data can greatly improve the surgical outcomes of tumor removal and prevent postoperative neurologic deficits.

Endotracheal Tube Electrode Neuromonitoring for Placement of Vagal Nerve Stimulation for Epilepsy: Intraoperative Stimulation Thresholds

ABSTRACT Vagal nerve stimulators (VNS) are indicated as a palliative treatment for medically refractory epilepsy. The vagus nerve may have a variable position within the carotid sheath and may be confused with a prominent ansa cervicalis. The objective of this study was to describe an intraoperative neuromonitoring technique for VNS placement and provide stimulation thresholds that may aid in the creation of stimulation protocols. A retrospective study was performed assessing 40 patients undergoing intraoperative vocal cord monitoring during vagal nerve stimulator placement surgery. Endotracheal electrodes were utilized to record vocal cord activity at various surgical time points. The stimulation thresholds were tested at the time of opening of the carotid sheath (mean 0.35 mA [range 0.08–1.00]), after full and circumferential dissection of the vagus nerve (0.34 mA [0.10–0.90]), after tenting of the vagus nerve in preparation for placement of the electrode (0.22 mA [0.06–1.20]), and after electrode placement (0.26 mA [0.05–1.20]). The vagus nerve was identified in all patients; it was located behind the common carotid artery (CCA) in two patients, on top of the internal jugular vein (IJV) in one patient, and in the typical location between the CCA and IJV in the remainder of patients. The average size of the vagus nerve was 2.9 mm [1.5–5.0]. Intraoperative vagus nerve stimulation represents a safe adjunctive tool that can help localize the nerve, particularly in the setting of varying anatomy or hazardous dissections. It may help reduce the potential for vagal trunk damage or electrode misplacement and potentially improve clinical outcomes.

240. Utility of intraoperative neuromonitoring alerts relating to adverse outcomes in spine surgery: a study of 289 patients

<h3>BACKGROUND CONTEXT</h3> Although rare, one of the most problematic complications during spine surgery is neurologic injury with subsequent deficit. The use of multimodal intraoperative neuromonitoring (MIOM) during spine surgery provides the surgical team with real-time assessment of the neurological physiology and function. MIOM is thought to be sensitive and specific for identifying perioperative neurological injury in spinal surgery especially deformity surgery. However, results from recent studies have cast doubt on the effectiveness of certain MIOM techniques in detecting neurological injury in spine surgery patients. <h3>PURPOSE</h3> The purpose of this study was to improve spine surgery patient safety and outcomes by minimizing the incidence of postoperative new neurological deficits correlated to intraoperative neuromonitoring alerts from two neuromonitoring signals: motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs). <h3>STUDY DESIGN/SETTING</h3> A multicenter, multisurgeon prospective quality improvement initiative that was performed in conjunction with neuro alert (NA) monitoring services. All data was retrospectively analyzed. <h3>PATIENT SAMPLE</h3> A total of 289 patients who (1) received nondeformity lumbar (45%), cervical (45%) or thoracic (10%) surgery between July 2018 and July 2019 and (2) underwent SSEP and MEP monitoring throughout the entire surgery. <h3>OUTCOME MEASURES</h3> This study investigated the incidence of immediate postoperative (≤ 48 hours) new neurological deficits. sensitivty, specificity, postive predictive value (PPV), and negative predictive value (NPV) was calculated for the SSEP and MEP signals. <h3>METHODS</h3> This study was a multicenter, multisurgeon prospective quality improvement initiative that was performed in conjunction with neuro alert (NA) monitoring services. All neuromonitoring was carried out in accordance with the guidelines set forth by the American Academy of Neurology and the American Board for Neurophysiological Monitoring Programs. Two commonly used MIOM signals were tracked: somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs). Intraoperative data were recorded using a paper data collection tool. SSEP and MEP signal changes were classified as alerts based on the following best practices guidelines outlined in the literature: 50% or greater decrease in signal amplitude and/or a 10% or greater increase in signal latency with no signal recovery. Immediate postoperative (≤ 48 hours) new neurological deficit status was assessed for all patients. Neurological deficit information was recorded via paper during a postoperative physical exam that all physicians conducted on the patient within 48 hours after surgery. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the SSEP and MEP signals were calculated. <h3>RESULTS</h3> SSEP and MEP neuromonitoring data was analyzed for 289 patients who (1) received non-deformity lumbar (45%), cervical (45%) or thoracic (10%) surgery between July 2018 and July 2019 and (2) underwent SSEP and MEP monitoring throughout the entire surgery. A total of 22 MEP and 16 SSEP alerts were triggered. Ninety percent (20) of MEP alerts occurred during anterior cervical discectomy and fusion (ACDF) procedures; one MEP alert was triggered during a posterior cervical fusion and one MEP alert was triggered during a lumbar laminectomy. 56% (9) of SSEP alerts occurred during transforaminal lumbar interbody fusion procedures while 25% (4) occurred during ACDFs and 19% (3) occurred during lumbar laminectomy surgeries. MEP and SSEP alerts were most frequently triggered during the decompression surgical step (45% and 25%, respectively). There were 6 instances (n = 6) of new neurological deficits that occurred within 48 hours postsurgery. These deficits were as follows: foot drop (n = 1), leg weakness (n = 1), arm weakness (n = 2), bilateral paraparesis (n = 1) and unilateral paraparesis (n = 1). The patient who developed unilateral paraparesis was myelopathic. All other patients with new neurological deficits did not have a history of myelopathy. The MEP alert should have been triggered for all 6 patients, however the signal was only alerted in the patient who developed bilateral paraparesis and in one patient who developed arm weakness. In 4/6 patients, MEP alerts were not triggered but a new neurological deficit occurred, resulting in a false negative rate of 67% and a sensitivity of 33%. In addition, MEPs had a specificity of 92.4%, PPV of 11% and NPV of 98.5%. The SSEP signal showed 100% sensitivity and displayed a specificity, PPV and NPV of 95.2%, 12.5% and 100%, respectively. <h3>CONCLUSIONS</h3> The MEP signal had a low sensitivity of 33%, which differed greatly from that of the SSEP signal (100%). The specificity, PPV and NPV were comparable between the SSEPs and MEPs. The PPV was low for both signals. Results indicate that the accuracy of SSEP and MEP alerts in detecting new neurological deficits in spine surgery patients immediately postsurgery is questionable. The effectiveness of these two intraoperative neuromonitoring techniques in identifying neurological injury seems uncertain and needs to be explored further. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs

Intraoperative Neuromonitoring During Resection of Gliomas Involving Eloquent Areas.

In the case of resection of gliomas involving eloquent areas, equal consideration should be given to maintain maximal extent of resection (EOR) and neurological protection, for which the intraoperative neuromonitoring (IONM) proves an effective and admirable approach. IONM techniques applied in clinical practice currently consist of somatosensory evoked potential (SSEP), direct electrical stimulation (DES), motor evoked potential (MEP), electromyography (EMG), and electrocorticography (ECoG). The combined use of DES and ECoG has been adopted widely. With the development of technology, more effective IONM tactics and programs would be proposed. The ultimate goal would be strengthening the localization of eloquent areas and epilepsy foci, reducing the incidence of postoperative dysfunction and epilepsy improving the life quality of patients.

Efficacy of Intraoperative Neuromonitoring during Thyroidectomy with Transcutaneous Adhesive Skin Electrodes

Background and Objectives Variable types of electrodes for intraoperative neuromonitoring (IONM) during thyroid surgery have been introduced to make up for the shortcomings of conventional endotracheal electromyogram tube. In this study, we sought to evaluate the efficacy of transcutaneous adhesive skin electrodes for IONM of recurrent laryngeal nerve (RLN) during thyroidectomy.Subjects and Method A total 97 nerves at risk of 80 patients were enrolled in this study. Two disposable adhesive skin electrodes were attached at both upper margins of thyroid cartilage. Using NIM 3.0 system (Medtronic), we recorded the amplitude and latency of signals of vagus nerve and RLN following the standard procedure of IONM. Clinicopathologic factors as well as the preoperative and postoperative vocal cord functions of the patients were analyzed.Results IONM was successful in all nerves at risk without any false loss of signals. There were no complications nor any significant time delay due to adhesive skin electrodes. The mean amplitudes from the vagus nerve (V1) and RLN (R1) were 230.64 µV and 293.48 µV, respectively. Two nerves at risk showed loss of signal and the two patients showed postoperative temporary vocal cord paralysis. The amplitude of signals from the vagus nerve (V1, V2) was significantly higher in the lower body mass index (BMI) group compared to that of the higher BMI group.Conclusion IONM using transcutaneous skin electrodes may be considered as an alternative technique for IONM during thyroid surgery.

Transabdominal Motor Action Potentials (Tamap) for Lateral Approach Neuromonitoring in Spine Surgery: Novel Case Series of 51 Patients in Proof-ofConcept Demonstration

Background: Risk of nerve injury is well-documented in lateral approach spine surgery. Advanced intraoperative neuromonitoring techniques may improve false positive and false negative rates of traditional methods to decrease complications. Objective: Determine the safety, sensitivity, and methodological validity of transabdominal motor action potentials (TaMAP) recordings in lateral access spine surgery. Methods: Institutional Review Board approval was obtained for the prospective collection of patient data. Cathode and anode leads were placed on the posterior and anterior surfaces of back and abdomen, and motor responses were recorded by subdermal needle electrodes in 6 target muscles. Voltage and stimulation amplitude were measured at preoperative baseline, postoperative, and new baseline time points, and compared for muscle groups relevant to symptoms and operative approach. Results: In a total of 51 cases of lateral approach surgery, stimulation sensitivity was 100% for vastus medialis, anterior tibialis, and adductor magnus, followed by 98% in biceps femoris, 95% in gastrocnemius, and 33% for vastus lateralis measures. Decompression at L5/S1 resulted in a decrease in voltage in right gastrocnemius in 80% of cases, 80% of right vastus medialis (L3/L4), and in 58% of right anterior tibialis recordings (L4/5). No postoperative neurological complications were observed. Conclusions: TaMAP intraoperative monitoring is a safe, reliable, and sensitive MEP measure with ease-of-use that may serve as an alternative resource in neuromonitoring for spinal surgery. Sensitivity was observed to be as high as 100% for 3/6 muscle groups tested and with robust efficacy of decompression across a variety of procedures and pathologies, including degenerative spine disease and spinal tumor.

Technique for Intraoperative Neuromonitoring During Periacetabular Osteotomy After Concomitant Hip Arthroscopy

Intraoperative neurologic injury during periacetabular osteotomy (PAO) for the treatment of symptomatic acetabular dysplasia is a major complication that can lead to permanent disability and limit the benefit of correcting the acetabular dysplasia. Current literature reflects the evolution of hip-preservation surgery for symptomatic acetabular dysplasia to include hip arthroscopy to address the intra-articular abnormalities, including labral tears, chondral lesions, and femoral cam morphology. A growing number of young hip surgeons and surgeon teams are subscribing to this approach and now performing concomitant hip arthroscopy and PAO. The value of intraoperative neuromonitoring cannot be understated, both in terms of surgeon confidence as well as patient safety, particularly during the learning curve of PAO, with or without hip arthroscopy. We present our current technique for the application of neuromonitoring to allow free mobility of the operative leg and continuous monitoring during PAO. This reproducible technique allows the use of nonsterile neuromonitoring to be used through a sterile conduit, positioned to allow free mobility of the operative extremity and performance of the PAO. We believe this technique provides additional safety benefit and increases awareness regarding neurologic compromise, particularly for the low-volume PAO surgeon or during the procedural learning curve.