Electrode Misplacement Research Articles

Coupled and radiated microwave sensors for vital signs and lung water level monitoring

This paper presents a novel approach for non-invasive monitoring of vital signs (heart rate (HR), respiration rate (RR)) and lung water levels using ultra-wideband (UWB) microwave sensors. The primary contribution of this study is the development and testing of two different sensor technologies to enhance the penetration and monitoring capabilities of electromagnetic waves within the human body. The first sensor technology employs a radiated UWB microwave that can be integrated into textiles, operating within a frequency range of 1.5 to 10 GHz, providing flexibility and comfort for wearable health monitoring. The second sensor technology involves using body-coupled UWB non-radiating sensors with a wide operational bandwidth from 1.3 to 10 GHz and a stable feeding structure, ensuring efficient reflection and transmission of waves for accurate monitoring. The shapes of flexible and textile UWB electromagnetic microwave sensor radiators and couplers, along with the measurement procedure, are tested in human clinical studies. The sensor-specific absorption rate (SAR) is evaluated at two distinct resonant frequencies on tissue masses of 1 g and 10 g, aligning with the IEEE C95.3 standard to ensure adherence to standard thresholds of 1.6 W/kg and 2 W/kg, respectively. Additionally, a denoising scheme utilizing deep learning techniques is proposed to filter Base Line Wander (BLW) noise attributable to misplaced electrodes, skin impedance, poor skin preparation, patient movement, and breathing within the frequency range of 0.05 to 3 Hz. The postprocessing outcome demonstrates the superiority of couplers over radiating sensors.

Clinical Applicability and Safety of Conventional Frame-Based Stereotactic Techniques for Stereoelectroencephalography.

Stereoelectroencephalography (SEEG) is increasingly being recognized as an important invasive modality for presurgical evaluation of epilepsy. This study focuses on the clinical and technical considerations of SEEG investigations when using conventional frame-based stereotaxy, drawing on institutional experience and a comprehensive review of relevant literature. This retrospective observational study encompassed the surgical implantation of 201 SEEG electrodes in 16 epilepsy patients using a frame-based stereotactic instrument at a single tertiary-level center. We provide detailed descriptions of the operative procedures and technical nuances for bilateral and multiple SEEG insertions, along with several illustrative cases. Additionally, we present a literature review on the technical aspects of the SEEG procedure, discussing its clinical implications and potential risks. Frame-based SEEG electrode placements were successfully performed through sagittal arc application, with the majority (81.2%) of cases being bilateral and involving up to 18 electrodes in a single operation. The median skin-to-skin operation time was 162 minutes (interquartile range [IQR], 145-200), with a median of 13 minutes (IQR, 12-15) per electrode placement for time efficiency. There were two occurrences (1.0%) of electrode misplacement and one instance (0.5%) of a postoperative complication, which manifested as a delayed intraparenchymal hemorrhage. Following SEEG investigation, 11 patients proceeded with surgical intervention, resulting in favorable seizure outcomes for nine (81.8%) and complete remission for eight cases (72.7%). Conventional frame-based stereotactic techniques remain a reliable and effective option for bilateral and multiple SEEG electrode placements. While SEEG is a suitable approach for selected patients who are strong candidates for epilepsy surgery, it is important to remain vigilant concerning the potential risks of electrode misplacement and hemorrhagic complications.

Exploration of different electrode types inserted in a 3D model of a patient with incomplete partition type III inner ear malformation

BackgroundIncomplete partition type III (IP III) represents a rare malformation of the inner ear, posing challenges during cochlear implantation due to inevitable cerebrospinal fluid (CSF) leaks and the potential misplacement of electrodes within the internal auditory canal (IAC). Despite the absence of a consensus on electrode selection, literature suggests both straight and perimodiolar electrodes as viable options for proper insertion. Limited implantation series contribute to the ambiguity in electrode choice. In this study, we evaluated the insertion performance of three electrode types in a 3D model simulating an IP III patient's inner ear. MethodsA 3D model replicating the inner ear of a patient with IP III undergoing surgery was created, incorporating a canal wall up mastoidectomy and an enlarged round window approach. Insertions were carried out using a straight electrode, a perimodiolar electrode, and a slim perimodiolar electrode, inserted through a sheath in the basal turn of the cochlea. Electrode positions were assessed after each insertion, with each type being tested 20 times. ResultsSuccessful insertion rates were 95 % for the slim perimodiolar electrode, 85 % for the perimodiolar electrode, and 75 % for the slim straight electrode. Notably, the slim perimodiolar electrode required an adapted insertion technique due to the altered cochlear position in IP III cases. Statistical analysis revealed the slim perimodiolar electrode's superiority over the slim straight electrode in achieving successful insertions. ConclusionsThe 3D model of the IP III inner ear proved to be an effective tool for electrode testing and insertion training prior to surgery. Following multiple insertions in the 3D model, the slim perimodiolar electrode demonstrated the highest success rate, emphasizing its potential as the preferred choice for cochlear implantation in IP III cases.

Application of artificial intelligence in the diagnosis and treatment of cardiac arrhythmia.

The rapid growth in computational power, sensor technology, and wearable devices has provided a solid foundation for all aspects of cardiac arrhythmia care. Artificial intelligence (AI) has been instrumental in bringing about significant changes in the prevention, risk assessment, diagnosis, and treatment of arrhythmia. This review examines the current state of AI in the diagnosis and treatment of atrial fibrillation, supraventricular arrhythmia, ventricular arrhythmia, hereditary channelopathies, and cardiac pacing. Furthermore, ChatGPT, which has gained attention recently, is addressed in this paper along with its potential applications in the field of arrhythmia. Additionally, the accuracy of arrhythmia diagnosis can be improved by identifying electrode misplacement or erroneous swapping of electrode position using AI. Remote monitoring has expanded greatly due to the emergence of contactless monitoring technology as wearable devices continue to develop and flourish. Parallel advances in AI computing power, ChatGPT, availability of large data sets, and more have greatly expanded applications in arrhythmia diagnosis, risk assessment, and treatment. More precise algorithms based on big data, personalized risk assessment, telemedicine and mobile health, smart hardware and wearables, and the exploration of rare or complex types of arrhythmia are the future direction.

Improving EEG-based decoding of the locus of auditory attention through domain adaptation * *This paper is based on a Master’s Thesis work (Wilroth ).

Objective. This paper presents a novel domain adaptation (DA) framework to enhance the accuracy of electroencephalography (EEG)-based auditory attention classification, specifically for classifying the direction (left or right) of attended speech. The framework aims to improve the performances for subjects with initially low classification accuracy, overcoming challenges posed by instrumental and human factors. Limited dataset size, variations in EEG data quality due to factors such as noise, electrode misplacement or subjects, and the need for generalization across different trials, conditions and subjects necessitate the use of DA methods. By leveraging DA methods, the framework can learn from one EEG dataset and adapt to another, potentially resulting in more reliable and robust classification models. Approach. This paper focuses on investigating a DA method, based on parallel transport, for addressing the auditory attention classification problem. The EEG data utilized in this study originates from an experiment where subjects were instructed to selectively attend to one of the two spatially separated voices presented simultaneously. Main results. Significant improvement in classification accuracy was observed when poor data from one subject was transported to the domain of good data from different subjects, as compared to the baseline. The mean classification accuracy for subjects with poor data increased from 45.84% to 67.92%. Specifically, the highest achieved classification accuracy from one subject reached 83.33%, a substantial increase from the baseline accuracy of 43.33%. Significance. The findings of our study demonstrate the improved classification performances achieved through the implementation of DA methods. This brings us a step closer to leveraging EEG in neuro-steered hearing devices.

Intraoperative nerve stimulation during vagal nerve stimulator placement.

Vagal nerve stimulation (VNS) is a palliative treatment for refractory epilepsy and intraoperative nerve stimulation is applied to the vagal and other nerves to prevent electrode misplacement. We evaluated these thresholds to establish intraoperative monitoring procedures for VNS surgery. Forty-six patients who underwent intraoperative nerve stimulation during VNS placement were enrolled. The vagal nerve and other exposed nerves were electrically stimulated during surgery, and muscle contraction was confirmed by electromyography of the vocal cords and visual recognition of cervical muscle contraction. The nerve thresholds and the most sensitive parts of the vagal nerve were analyzed retrospectively. The stimulation of vagal nerves induced vocal cord responses in all 46 patients; the median thresholds of the most sensitive parts and all parts were 0.2 mA (range: 0.05-0.75 mA) and 0.25 mA (range: 0.15-1.5 mA), respectively. The medial middle region was identified as the most sensitive part of the vagal nerve in the majority of participants (82.5%). In 11 patients, other cervical nerves were stimulated and sternohyoid muscle contraction was induced with a median threshold of 0.35 mA (range: 0.1-0.7 mA) in eight patients, while sternocleidomastoid muscle contraction was induced with a median threshold of 0.2 mA (range: 0.1-0.2 mA) in three. Intraoperative stimulation of vagal nerves induces vocal cord responses with locational variations, and the middle part stimulation could minimize the stimulus intensities. The nerves innervating the sternohyoid and sternocleidomastoid muscles may be exposed during the procedure. Knowledge of these characteristics will enhance the effectiveness of this technique in future applications.

Cochlear implantation in Aksay University Clinic: A review of 135 cases

<b>Introduction:</b> Around 430 million people today suffer from mild to profound hearing loss and require rehabilitation. One option offered to patients with sensorineural hearing loss is cochlear implantation.</br></br> <b>Objective:</b> The aim of this study was to determine the complication rate after cochlear implantation over an 8-month period. All complications were divided into 3 main groups: minor postoperative, major postoperative, and device-related failures. Additionally, the methods for prevention and management are discussed.</br></br> <b>Study design:</b> Retrospective analysis of surgical complications after cochlear implantation.</br></br> <b>Methods:</b> Our study included a total of 135 children (65 boys and 70 girls) who underwent cochlear implantation in Aksay University Clinic from January 2022 to August 2022. The follow-up period ranged from 8 to 15 months. The mean age at the time of their respective procedures was 3.9 years (age range: 6 months – 17 years 8 months).</br></br> <b>Results:</b> A total of 21 complications (15.5%) were registered among the 135 patients. Of these, 9 (6.6%) were major complications and 12 (8.8%) were minor. The most prevalent cause of major complications was electrode misplacement (5 patients, 3.7%), while for minor complications it was hematoma (9 patients, 6.6%). In our study, there were more postoperative major complications and the number of complications was generally comparable to the world literature.</br></br> <b>Conclusion:</b> Cochlear implantation is a safe, modern surgical procedure for treating sensorineural hearing loss and it is associated with a low complication rate. However, patients have to be informed about all possible complications and surgeons have to know the means of optimal prevention.

Design of robust adaptive Volterra noise mitigation architecture for sEMG signals using metaheuristic approach

Surface Electromyogram (sEMG) signals, like other electrophysiological measurements, get corrupted by several artefacts; much critical helpful information regarding a person’s clinical conditions may alter or be lost entirely. Therefore, the sEMG signal must be filtered to minimise such artefacts. The drive of this paper is to propose an efficient adaptive Volterra noise mitigation architecture (AVNMA) for the sEMG signal. Further, the optimal coefficients for designing the Volterra filter architecture are achieved by applying the recently proposed metaheuristic algorithm, gannet optimisation algorithm and compared to the performance of other benchmark optimisation algorithms, namely harmony search optimisation algorithm and teaching learning-based optimisation algorithm to the proposed architecture. The quantitative analysis based on the proposed architecture is measured in terms of several metrics such as mean squared error, normalised root mean square error, peak reconstruction error, mean difference, maximum error and signal-to-noise ratio at various noisy environments in the presence of additive white Gaussian noise, including artefacts such as muscle noise, baseline wandering, electrode misplacements, and electrical interference. The outcomes of experimental research (SNR = 102.236 dB andMSE = 6.71E-09 for healthy-sEMG) ensure the superiority of the gannet optimisation algorithm based-AVNMA over the other metaheuristic algorithm based-AVNMAs. The proposed approach is verified parametrically and non-parametrically in a statistical sense with the help of two sample t-tests and the Mann-Whitney U test, respectively.

Simple, efficient, and generalized ECG signal quality assessment method for telemedicine applications

Electrocardiogram (ECG) signals recorded by paramedics in an unsupervised environment are prone to errors and noise due to factors such as electrode misplacements and daily activities during prolonged monitoring. Signal Quality Assessment (SQA) systems can prevent false diagnoses by automated arrhythmia detection systems and reduce the workload of cardiologists. However, current SQA methods are quite complex and/or exhibit poor performances in presence of certain arrhythmias. This study proposed a novel SQA method consisting of three main steps: (1) feasibility conditions check, (2) average beat correlation algorithm, and (3) beat clustering algorithm. The system uses empirical probability functions to automatically adapt the quality score according to the presence of pathological beats and/or noises. We evaluated the proposed method on three datasets and considered both three-quality classes ('Bad', 'HR' and 'Diagnostic') and two-quality classes ('Acceptable' and 'Unacceptable'). For the three-class classification, we obtained an average accuracy of 81.42 % while for the two-class, our algorithm achieved an average sensitivity of 94.59 %, a specificity of 98.38 %, and an accuracy of 97.10 %. The results show that our method achieves high accuracy, specificity and generalizability, outperforming the simple heuristic rule, machine learning, and deep learning methods. Additionally, the algorithm requires less computational time, making it suitable for telemedicine applications.

A Method of Intraoperative Registration Verification to Prevent Accuracy Errors in Robot-Assisted Stereotactic Electroencephalography Electrode Placement

Robotic-assisted stereotactic electroencephalography (sEEG) electrode placement is increasingly common at specialized epilepsy centers. High accuracy and low complication rates are essential to realizing the benefits of sEEG surgery. The aim of this study was to describe for the first time in the literature a method for a stereotactic registration checkpoint to verify intraoperative accuracy during robotic-assisted sEEG and to report our institutional experience with this technique. All cases performed with this technique since the adoption of robotic-assisted sEEG at our institution were retrospectively reviewed. In 4 of 111 consecutive sEEG operations, use of the checkpoint detected an intraoperative registration error, which was addressed before completion of sEEG electrode placement. The use of a registration checkpoint in robotic-assisted sEEG surgery is a simple technique that can prevent electrode misplacement and improve the safety profile of this procedure.

Stereoelectroencephalography before 2 years of age.

Stereoelectroencephalography (SEEG) is a widely used technique for localizing seizure onset zones prior to resection. However, its use has traditionally been avoided in children under 2 years of age because of concerns regarding pin fixation in the immature skull, intraoperative and postoperative electrode bolt security, and stereotactic registration accuracy. In this retrospective study, the authors describe their experience using SEEG in patients younger than 2 years of age, with a focus on the procedure's safety, feasibility, and accuracy as well as surgical outcomes. A retrospective review of children under 2 years of age who had undergone SEEG while at Children's Hospital of Philadelphia between November 2017 and July 2021 was performed. Data on clinical characteristics, surgical procedure, imaging results, electrode accuracy measurements, and postoperative outcomes were examined. Five patients younger than 2 years of age underwent SEEG during the study period (median age 20 months, range 17-23 months). The mean age at seizure onset was 9 months. Developmental delay was present in all patients, and epilepsy-associated genetic diagnoses included tuberous sclerosis (n = 1), KAT6B (n = 1), and NPRL3 (n = 1). Cortical lesions included tubers from tuberous sclerosis (n = 1), mesial temporal sclerosis (n = 1), and cortical dysplasia (n = 3). The mean number of placed electrodes was 11 (range 6-20 electrodes). Bilateral electrodes were placed in 1 patient. Seizure onset zones were identified in all cases. There were no SEEG-related complications, including skull fracture, electrode misplacement, hemorrhage, infection, cerebrospinal fluid leakage, electrode pullout, neurological deficit, or death. The mean target point error for all electrodes was 1.0 mm. All patients proceeded to resective surgery, with a mean follow-up of 21 months (range 8-53 months). All patients attained a favorable epilepsy outcome, including Engel class IA (n = 2), IC (n = 1), ID (n = 1), and IIA (n = 1). SEEG can be safely, accurately, and effectively utilized in children under age 2 with good postoperative outcomes using standard SEEG equipment. With minimal modification, this procedure is feasible in those with immature skulls and guides the epilepsy team's decision-making for early and optimal treatment of refractory epilepsy through effective localization of seizure onset zones.

Stretchable Textile Bands for Ambulatory Electrocardiogram and Oximetry

This work presents a vital sign monitoring interface combining electrocardiogram (ECG) and reflective photoplethysmography (PPG) acquisition on stretchable kinesiology tapes (KTs). The integrated textile bands are less prone to electrode misplacement and deliver high-quality diagnostic ECG signals with dry electrodes. The reflective PPG measured over the subclavian artery is used to track blood oxygen saturation, and in combination with ECG, enables the determination of pulse transit time and inference of blood pressure. This multimodal interface improves clinical workflows because it is easy to don, reduces motion artifacts, and facilitates more efficient and accurate diagnosis in emergency settings.

MRI-Guided Electrode Implantation for Chronic Intracerebral Recordings in a Rat Model of Post-Traumatic Epilepsy-Challenges and Gains.

Brain atrophy induced by traumatic brain injury (TBI) progresses in parallel with epileptogenesis over time, and thus accurate placement of intracerebral electrodes to monitor seizure initiation and spread at the chronic postinjury phase is challenging. We evaluated in adult male Sprague Dawley rats whether adjusting atlas-based electrode coordinates on the basis of magnetic resonance imaging (MRI) increases electrode placement accuracy and the effect of chronic electrode implantations on TBI-induced brain atrophy. One group of rats (EEG cohort) was implanted with two intracortical (anterior and posterior) and a hippocampal electrode right after TBI to target coordinates calculated using a rat brain atlas. Another group (MRI cohort) was implanted with the same electrodes, but using T2-weighted MRI to adjust the planned atlas-based 3D coordinates of each electrode. Histological analysis revealed that the anterior cortical electrode was in the cortex in 83% (25% in targeted layer V) of the EEG cohort and 76% (31%) of the MRI cohort. The posterior cortical electrode was in the cortex in 40% of the EEG cohort and 60% of the MRI cohort. Without MRI-guided adjustment of electrode tip coordinates, 58% of the posterior cortical electrodes in the MRI cohort will be in the lesion cavity, as revealed by simulated electrode placement on histological images. The hippocampal electrode was accurately placed in 82% of the EEG cohort and 86% of the MRI cohort. Misplacement of intracortical electrodes related to their rostral shift due to TBI-induced cortical and hippocampal atrophy and caudal retraction of the brain, and was more severe ipsilaterally than contralaterally (p < 0.001). Total lesion area in cortical subfields targeted by the electrodes (primary somatosensory cortex, visual cortex) was similar between cohorts (p > 0.05). MRI-guided adjustment of coordinates for electrodes improved the success rate of intracortical electrode tip placement nearly to that at the acute postinjury phase (68% vs. 62%), particularly in the posterior brain, which exhibited the most severe postinjury atrophy. Overall, MRI-guided electrode implantation improved the quality and interpretation of the origin of EEG-recorded signals.

The case for intra-operative X-ray in cochlear implantation: Four illustrative cases and literature review

Objectives: To demonstrate the utility of routine intraoperative plain film imaging in optimizing outcomes in cochlear implantation. Introduction: Evolving surgical techniques, programming, and electrode arrays have all improved performance outcomes in cochlear implantation. Yet despite decreasing complication rates, electrode misplacement remains a common occurrence. Utilization of intraoperative confirmational tools (radiologic, electrophysiologic) remains unstandardized despite the acknowledged importance of proper electrode positioning. The purpose of this article is to illustrate the use and benefits of intraoperative X-ray (IOXR) in four cases, particularly in cases of normal electrophysiologic testing. Methods: Four cases performed by an experienced CI surgeon are discussed where electrode malposition was only detected through X-ray. Literature review was performed on the use of intraoperative imaging, focusing on plain film radiography. Results: Case 1–3 describe examples of resistance-free electrode insertion in patients with normal pre-operative imaging. Intraoperative impedances and neural response telemetry (NRT) were normal. However, IOXR ultimately revealed tip fold-over prompting array repositioning. Case 4 describes an elective replacement of a soft-failing device. Resistance was encountered during array insertion, with IOXR demonstrating incomplete insertion compared with prior imaging. Positioning was revised to achieve pre-revision insertion depth, demonstrating the utility of prior IOXR in revision cases. Literature review of IOXR is discussed. Conclusion: Appropriate placement of the electrode is paramount to successful CI outcomes. These cases illustrate IOXR as a safe, effective method to ensure optimal placement even in cases of normal electrophysiologic testing, supporting its routine use even by the most seasoned surgeons.

Comparison of placement time duration between precordial lead of ECG Safone and Standard ECG

Introduction: The misplacement of precordial electrodes in the electrocardiography (ECG) recording sometimes occurs in the field. Therefore, it needs a simple and easy use of precordial electrodes of ECG that can determine the position of the precordial electrodes fast and accurately. Objectives: This study aimed to compare placement time duration between the precordial lead of ECG SafOne and the precordial lead of standard ECG. Methods: This study employed an experimental study design with a post-test-only equivalent group method. There were 30 subjects involved in this study who were selected using purposive technic sampling. All-time durations of precordial lead placement gained from subjects using both ECG SafOne and standard ECG were identified and measured. Data were analyzed using Wilcoxon signed-rank test to compare the precordial lead of ECG SafOne and standard ECG. Results: The results showed that most subjects involved were elderly (56-65 years old) (46,7 %) and most were male (60%). The result of this study showed that the average placement time duration for ECG SafOne precordial lead is 52,90 seconds, while standard ECG precordial lead is 152,9 seconds. Based on bivariate analysis, there is a remarkable difference in the placement time duration of precordial lead between ECG SafOne and standard ECG with a p-value of 0,000 &lt; α (0,05). Conclusions: The time duration of precordial lead placement of ECG SafOne is significantly faster than standard ECG. To some extent, the result of this study has a beneficial implication for health care professionals in terms of providing professional services by reducing the time to record electrocardiography.

Accurate and Robust Locomotion Mode Recognition Using High-Density EMG Recordings from a Single Muscle Group.

Existing methods for human locomotion mode recognition often rely on using multiple bipolar electrode sensors on multiple muscle groups to accurately identify underlying motor activities. To avoid this complex setup and facilitate the translation of this technology, we introduce a single grid of high-density surface electromyography (HDsEMG) electrodes mounted on a single location (above the rectus femoris) to classify six locomotion modes in human walking. By employing a neural network, the trained model achieved average recognition accuracy of 97.7% with 160ms latency, significantly better than the model trained with one bipolar electrode pair placed on the same muscle (71.4% accuracy). To further exploit the spatial and temporal information of HDsEMG, we applied data augmentation to generate artificial data from simulated displaced electrodes, aiming to counteract the influence of electrode shifts. By employing a convolutional neural network with the enhanced dataset, the updated model was not strongly affected by electrode misplacement (93.9% accuracy) while models trained by bipolar electrode data were significantly disrupted by electrode shifts (29.4% accuracy). Findings suggest HDsEMG could be a valuable resource for mapping gait with fewer sensor locations and greater robustness. Results offer future promise for real-time control of assistive technology such as exoskeletons.

Cochlear Implant Electrode Misplacement: A Case Series and Contemporary Review.

To determine root causes leading to misplaced cochlear implant (CI) electrode arrays and discuss their management using a case series and contemporary literature review. Retrospective case review and contemporary literature review. Single tertiary-referral center. Adult and pediatric patients who were diagnosed with a misplaced CI electrode array, excluding tip-foldover. Literature review was performed via a MEDLINE database PubMed query. All articles that described at least one case of extracochlear electrode array misplacement were included; partial insertions and extrusions were excluded. Extracochlear misplacement. A total of 61 cases were reviewed, including 4 new cases and 57 cases from 29 previously published articles. We discuss management of CI arrays in the carotid canal, the vestibule, and the modiolus. The rate of CI misplacement is estimated to be 0.49%. The most frequent location of misplacement CI was the vestibular system (50.8%) followed by the internal carotid canal (11.5%). Normal cochlear anatomy was noted on preoperative computer tomography (CT) in 59.0% of patients; abnormalities were noted in 27.9%. The most common technical issue was misidentification or poor visualization of the round window. CI electrode misplacement is rare but can cause postoperative complications and may result in permanently diminished CI performance and hearing outcomes, even after revision surgery. Failure to identify the round window is the most common reason for CI misplacement, despite most patients having normal cochlear anatomy. Surgical strategies to localize the round window and basal turn are imperative for proper electrode placement. 4.

Cochlear Implants for Patients With Common Cavity Deformities and the Impact of Electrode Positioning.

ObjectivesCommon cavity deformity is a rare congenital bony labyrinth malformation associated with profound hearing loss. Cochlear implants are widely used for hearing rehabilitation for common cavity deformities; however, the reported prognosis is poor. Due to the deformed anatomical structure, it is important to consider the position of the electrodes to maximize the performance of the cochlear implant. The present study discusses the impact of electrode placement on hearing outcomes.MethodsA retrospective medical chart review of eight common cavity deformity patients (10 cochlear implants) who received cochlear implants was performed at a single university hospital. In all eight patients, implant surgery was performed using single-slit labyrinthotomy. Electrodes wer e manually bent before insertion to prevent misplacement and to reduce physical damage to the neuroepithelium.ResultsFour of the 10 electrodes were misplaced, with their tips placed in the anterior semicircular canal or internal auditory canal. However, after implant surgery, all patients—including those with misplaced electrodes—gained auditory perception and improved hearing function. One patient who had electrodes that did not contact the inner wall of the cavity showed limited activity of the electrodes (27%) compared to others (64%–100%).ConclusionProper contact of the electrode with the inner wall was more likely to be important for cochlear implant success in cases of common cavity deformity than appropriate placement of the electrode tip.

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.

Neural networks for classification of strokes in electrical impedance tomography on a 3D head model

&lt;abstract&gt;&lt;p&gt;We consider the problem of the detection of brain hemorrhages from three-dimensional (3D) electrical impedance tomography (EIT) measurements. This is a condition requiring urgent treatment for which EIT might provide a portable and quick diagnosis. We employ two neural network architectures - a fully connected and a convolutional one - for the classification of hemorrhagic and ischemic strokes. The networks are trained on a dataset with $ 40\, 000 $ samples of synthetic electrode measurements generated with the complete electrode model on realistic heads with a 3-layer structure. We consider changes in head anatomy and layers, electrode position, measurement noise and conductivity values. We then test the networks on several datasets of unseen EIT data, with more complex stroke modeling (different shapes and volumes), higher levels of noise and different amounts of electrode misplacement. On most test datasets we achieve $ \geq 90\% $ average accuracy with fully connected neural networks, while the convolutional ones display an average accuracy $ \geq 80\% $. Despite the use of simple neural network architectures, the results obtained are very promising and motivate the applications of EIT-based classification methods on real phantoms and ultimately on human patients.&lt;/p&gt;&lt;/abstract&gt;