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Study Design: Retrospective study.Objective: The purpose of this study was to assess the diagnostic usefulness of flexion-extension central motor conduction time(CMCT) for patients with cervical spondylotic myelopathy (CSM).Summary Of Background Data: Previous reports have suggested that cervical cord compression can be aggravated by neck motions. Thus, the importance of dynamic magnetic resonance imaging (MRI) has been emphasized. However, authors of this study found no reports conducted at the time of this research on whether flexion-extension CMCT was useful for detecting myelopathy.Methods: We enrolled 227 patients with CSM for this study. We acquired CMCT recorded from the abductor pollicis brevis muscle. All patients underwent a dynamic CMCT study during neck flexion and extension as well as a static study during neutral neck. Static and dynamic MRIs were also scanned. We read all MR images using Muhle classification (MC).Results: CMCT was significantly delayed with flexion (P < 0.01) and extension (P < 0.01) compared to neutral neck position. Patients with MC grade 1 and 2 showed significant lag in CMCT during flexion and extension. No significant lag by neck motion was observed for those in the MC grade 3. We also evaluated the amount of CMCT variation according to MC grade change (G0, G1, G2) by neck motion. Delta-CMCT of both G1 and G2 were significantly larger than those of G0 in both flexion and extension. In neutral neck, the CMCT showed significant difference between MC grades 1 and 3. They also displayed significant delay with delay with high signal intensity on T2 MRI. More than one-third of the patients whose CMCT was within normal range in neutral neck presented abnormal CMCT in neck flexion (35.3%) and extension (37.8%).Conclusion: CMCT is significantly slower in both neck flexion and neck extension than in the neutral neck position. These findings reflect the dynamic cervical cord impingement.Level of Evidence: 4. [ABSTRACT FROM AUTHOR]

In tonal languages, tone perception involves the processing of both acoustic and phonological information conveyed by tonal signals. In Mandarin, in addition to four canonical full tones, there exists a group of weak syllables known as neutral tones. This study aims to investigate the impact of lexical frequency effects and prosodic information associated with neutral tones on the auditory representation of Mandarin compounds. We initially selected disyllabic compounds as targets, manipulating their lexical frequencies and prosodic structures. Subsequently, these target compounds were embedded into selected sentences and auditorily presented to native speakers. During the experiments, participants engaged in lexical decision tasks while their event-related potentials were recorded. The results showed that the auditory lexical representation of disyllabic compounds was modulated by lexical frequency effects. Rare compounds and compounds with rare first constituents elicited larger N400 effects compared to frequent compounds. Furthermore, neutral tones were found to play a role in the processing, resulting in larger N400 effects. Our findings showed significantly increased amplitudes of the N400 component, suggesting that the processing of rare compounds and compounds with neutral tones may require more cognitive resources. Additionally, we observed an interaction effect between lexical frequency and neutral tones, indicating that they could serve as determining cues in the auditory processing of disyllabic compounds., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: Gender differences in pedestrian hazard perception were investigated using the event-related potential technique., Methods: The study utilized images of two types of real traffic situations as test materials: hazard situations and nonhazard situations. The presence of hazards in the displayed situations was determined by 30 adult subjects (including 17 females), who indicated their observations by pressing a button., Results: The results revealed that females exhibited a shorter N1 latency in hazard situations, while males exhibited a larger P3 amplitude compared to females., Conclusion: These results indicate that females are more sensitive to hazard situations during the early visual processing stage, while males give more attention to traffic situations during the late attention allocation stage., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The shape and position of cochlear implant electrodes could potentially influence speech perception, as this determines the proximity of implant electrodes to the spiral ganglion. However, the literature to date reveals no consistent association between speech perception and either the proximity of electrode to the medial cochlear wall or the depth of insertion. These relationships were explored in a group of implant recipients receiving the same precurved electrode., Methods: This was a retrospective study of adults who underwent cochlear implantation with Cochlear Ltd.'s Slim Perimodiolar electrode at the Royal Victorian Eye and Ear Hospital between 2015 and 2018 (n = 52). Postoperative images were obtained using cone beam computed tomography (CBCT) and analyzed by multi-planar reconstruction to identify the position of the electrode contacts within the cochlea, including estimates of the proximity of the electrodes to the medial cochlear wall or modiolus and the angular depth of insertion. Consonant-vowel-consonant (CVC) monosyllabic phonemes were determined preoperatively, and at 3 and 12 months postoperatively. Electrically evoked compound action potential (ECAP) thresholds and impedance were measured from the implant array immediately after implantation. The relationships between electrode position and speech perception, electrode impedance, and ECAP threshold were an analyzed by Pearson correlation., Results: Age had a negative impact on speech perception at 3 months but not 12 months. None of the electrode-wide measures of proximity between electrode contacts and the modiolus, nor measures of proximity to the medial cochlear wall, nor the angular depth of insertion of the most apical electrode correlated with speech perception. However, there was a moderate correlation between speech perception and the position of the most basal electrode contacts; poorer speech perception was associated with a greater distance to the modiolus. ECAP thresholds were inversely related to the distance between electrode contacts and the modiolus, but there was no clear association between this distance and impedance., Conclusions: Speech perception was significantly affected by the proximity of the most basal electrodes to the modiolus, suggesting that positioning of these electrodes may be important for optimizing speech perception. ECAP thresholds might provide an indication of this proximity, allowing for its optimization during surgery., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2024, Otology & Neurotology, Inc.)

Purpose: Repetitive ocular vestibular evoked myogenic potentials (ROVEMP) are a novel diagnostic test to quantify neuromuscular transmission deficits in extraocular muscles in myasthenia gravis. We aimed to investigate the test-retest reliability of the ROVEMP and the effect of amplitude and age., Methods: We performed the ROVEMP test twice in 19 patients with myasthenia gravis (52.7 ± 19.8 years) and in 15 healthy control subjects (46.5 ± 16 years). The Bland-Altman level of agreement was determined. The relationship between test-retest reliability and signal quality, participant age and signal amplitude was studied., Results: Limits of agreement were from -179.9 to 139.3 in myasthenia gravis patients and from -56.9 to 89.5 in healthy control subjects. Difference between measurements correlated with signal amplitude ( r = -0.50, P < 0.001). Combining the primary cohort with previously published data from 114 subjects, we found a significant negative correlation between age and reference amplitude ( r = -0.163, P = 0.045)., Conclusions: This study shows that in our hands, the test-retest reliability of the ROVEMP is not optimal. Measurements with higher reference amplitude had a better quality, higher reproducibility, and increased diagnostic yield. We caution against the use of ROVEMP measurements of lower amplitude in clinical practice. In addition, given the correlation between age and amplitude, age matching of healthy control subjects and patients is essential in future studies., Competing Interests: J. J.G.M. Verschuuren has been involved in MG research sponsored by the Princes Beatrix Fonds, Health Holland and consultancies for Argen-X, Alexion, Rapharma and NMD Pharma. He is coinventor on patent applications based on MuSK-related research. The Leiden University Medical Center receives royalties for MuSK antibody assays. M. R. Tannemaat reports trial support from Argen-X and Alexion and consultancies for NMD Pharma and UCB Pharma. All reimbursements were received by the Leiden University Medical Center, and M. R. Tannemaat and J. Venhovens have received no personal financial benefit from these activities. The authors are members of the European Reference Network for Rare Neuromuscular Diseases [ERN EURO-NMD]. The remaining authors have no conflicts of interest., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Clinical Neurophysiology Society.)

Objectives: The aim of this study was to evaluate the prognostic performance of the peak amplitude of P25/30 cortical somatosensory evoked potentials in predicting nonawakening in targeted temperature management-treated cardiac arrest patients.Design: Prospective analysis.Setting: Four academic tertiary care hospitals.Patients: Eighty-seven cardiac arrest survivors after targeted temperature management.Interventions: Analysis of the amplitude of P25/30.Measurements and Main Results: In all participants, somatosensory evoked potentials were recorded after rewarming, and bilaterally absent pupillary and corneal reflexes were evaluated at 72 hours after the return of spontaneous circulation. We analyzed the amplitudes of the N20 and P25/30 peaks and the N20-P25/30 complex in cortical somatosensory evoked potentials. Upon hospital discharge, 87 patients were dichotomized into the awakening and nonawakening groups. The lowest amplitudes of N20, P25/30, and N20-P25/30 in the awakening patients were 0.17, 0.45, and 0.73 μV, respectively, and these thresholds showed a sensitivity of 70.5% (95% CI, 54.8-83.2%), 86.4% (95% CI, 72.7-94.8%), and 75.0% (95% CI, 59.7-86.8%), respectively, for nonawakening. The area under the curve of the P25/30 amplitude was significantly higher than that of the N20 amplitude (0.955 [95% CI, 0.912-0.998] vs 0.894 [95% CI, 0.819-0.969]; p = 0.036) and was comparable with that of the N20-P25/30 amplitude (0.931 [95% CI, 0.873-0.989]). Additionally, adding resuscitation variables or an absent brainstem reflex to the P25/30 amplitude showed a trend toward improving prognostic performance compared with the use of other somatosensory evoked potential amplitudes (area under the curve, 0.958; 95% CI, 0.917-0.999 and area under the curve, 0.974; 95% CI, 0.914-0.996, respectively).Conclusions: Our results provide evidence that the absence of the P25/30 peak and a reduction in the P25/30 amplitude may be considered prognostic indicators in these patients. [ABSTRACT FROM AUTHOR]

Objective: The proportion congruency effect has been reported in interference tasks. The mostly congruent block is the frequent condition, and the mostly incongruent block is the rare condition for congruent stimuli, whereas the mostly congruent block is the rare condition, and the mostly incongruent block is the frequent condition for incongruent stimuli. This study examined the cognitive mechanism underlying the proportion congruency effect in the two-choice Stroop task using event-related potential components related to deviant processing., Method: Stimuli were Kanji characters meaning 'red' and 'blue' painted by congruent and incongruent colors. Participants were required to provide a two-choice button-press response corresponding to the colors. The congruent and incongruent stimuli were presented on rare (20%) and frequent (80%) conditions., Results: N1 was enhanced in the rare condition relative to the frequent condition for both congruent and incongruent stimuli. The results suggested that colors and characters were not processed independently in the N1 time range, which made selective attention to the relevant feature difficult. Posterior negativity from 200 to 250 ms was also different between rare and frequent conditions, indicating the presence of visual mismatch negativity for congruent and incongruent stimuli. It was considered that the distinction between congruent and incongruent stimuli was evident in mostly incongruent blocks, indicating that the selective attention mechanism was not actively engaged., Conclusion: The proportion congruency effect was explained by contingency learning rather than selective attention in the present task. The cognitive mechanisms underlying the proportion congruency effect are reflected by deviant event-related potential components., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

We can solve insight problems by ourselves, by hints or by answers. This study compared the temporal features of different types of insight (spontaneous insight, induced insight by hints and induced insight by answers). Fifteen college students participated in the Chinese Remote Association Task. If they did not come up with an answer, the cue word was presented. Finally, they needed to judge whether the answer was correct or not. Participants' brain electroencephalography-event-related potentials (ERPs) were recorded. Induced insight by hints elicited a more negative ERP deflection than spontaneous insight within 260-400 ms (N2). Induced insight by hints and induced insight by answers elicited a more negative late negative component (LNC) than spontaneous insight. Induced insight by hints elicited a more positive ERP deflection than induced insight by answers and spontaneous insight in the right frontal area. Spontaneous insight and induced insight by answers elicited a more positive ERP deflection than induced insight by hints in the right part of the central region. When solving insight problems, the N2 may be related to representation restructuring. The first LNC may be related to the breaking of mental set. The positive component of the right frontal area before pressing the button may be related to the formation of novel associations, and the positive component of the right part of the central region may be related to the intensity of the 'Aha!' experience., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

The virtual reality (VR) environment is claimed to be highly immersive. Participants may thus be potentially unaware of their real, external world. The present study presented irrelevant auditory stimuli while participants were engaged in an easy or difficult visual working memory (WM) task within the VR environment. The difficult WM task should be immersive and require many cognitive resources, thus few will be available for the processing of task-irrelevant auditory stimuli. Sixteen young adults wore a 3D head-mounted VR device. In the easy WM task, the stimuli were nameable objects. In the difficult WM task, the stimuli were abstract objects that could not be easily named. A novel paradigm using event-related potentials (ERPs) was implemented to examine the feasibility of quantifying the extent of processing of task-irrelevant stimuli occurring outside of the VR environment. Auditory stimuli irrelevant to the WM task were presented concurrently at every 1.5 or 12 s in separate conditions. Performance on the WM task varied with task difficulty, with accuracy significantly lower during the difficult task. The auditory ERPs consisted of N1 and a later P2/P3a deflection which were larger when the auditory stimuli were presented slowly. ERPs were unaffected by task difficulty, but significant correlations were found. N1 and P2/P3a amplitudes were smallest when performance on the Easy WM task was highest. It is possible that even the easy WM task was so immersive and required many processing resources that few were available for the co-processing of the task-irrelevant auditory stimuli., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: Absence of somatosensory evoked potentials is considered a nearly perfect predictor of poor outcome after cardiac arrest. However, reports of good outcomes despite absent somatosensory evoked potentials and high rates of withdrawal of life-sustaining therapies have raised concerns that estimates of the prognostic value of absent somatosensory evoked potentials may be biased by self-fulfilling prophecies. We aimed to develop an unbiased estimate of the false positive rate of absent somatosensory evoked potentials as a predictor of poor outcome after cardiac arrest.Data Sources: PubMed.Study Selection: We selected 35 studies in cardiac arrest prognostication that reported somatosensory evoked potentials.Data Extraction: In each study, we identified rates of withdrawal of life-sustaining therapies and good outcomes despite absent somatosensory evoked potentials. We appraised studies for potential biases using the Quality in Prognosis Studies tool. Using these data, we developed a statistical model to estimate the false positive rate of absent somatosensory evoked potentials adjusted for withdrawal of life-sustaining therapies rate.Data Synthesis: Two-thousand one-hundred thirty-three subjects underwent somatosensory evoked potential testing. Five-hundred ninety-four had absent somatosensory evoked potentials; of these, 14 had good functional outcomes. The rate of withdrawal of life-sustaining therapies for subjects with absent somatosensory evoked potential could be estimated in 14 of the 35 studies (mean 80%, median 100%). The false positive rate for absent somatosensory evoked potential in predicting poor neurologic outcome, adjusted for a withdrawal of life-sustaining therapies rate of 80%, is 7.7% (95% CI, 4-13%).Conclusions: Absent cortical somatosensory evoked potentials do not infallibly predict poor outcome in patients with coma following cardiac arrest. The chances of survival in subjects with absent somatosensory evoked potentials, though low, may be substantially higher than generally believed. [ABSTRACT FROM AUTHOR]

Introduction: Demonstration of nociceptive fiber abnormality is important for diagnosing neuropathic pain and small fiber neuropathies. This is usually assessed by brief heat pulses using lasers, contact heat, or special electrodes. We hypothesized that pain-related evoked potentials to conventional surface electrical stimulation (PREPse) can index Aδ afferences despite tactile Aß fibers coactivation. PREPse may be more readily used clinically than contact heat evoked potentials (CHEPS)., Methods: Twenty-eight healthy subjects. Vertex (Cz-A1/A2) recordings. Electrical stimulation of middle finger and second toe with conventional ring, and forearm/leg skin with cup, electrodes. Contact heat stimulation to forearm and leg. Compression ischemic nerve blockade., Results: PREPse peripheral velocities were within the midrange of Aδ fibers. N1-P1 amplitude increased with pain numerical rating scale graded (0-10) electrical stimulation (n = 25) and decreased with increasing stimulation frequency. Amplitudes were unchanged by different presentation orders of four stimulation intensities. PREPse N1 (∼130 milliseconds) and N2 (∼345 milliseconds) peaks were approximately 40 milliseconds earlier than that with CHEPS. PREPse and CHEPS N1-N2 interpeak latency (∼207 milliseconds) were similar. PREPse became unrecordable with nerve blockade of Aδ fibers., Conclusions: PREPse earlier N1 and N2 peaks, and similar interpeak N1-N2 latencies and central conduction velocities, or synaptic delays, to CHEPS are consistent with direct stimulation of Aδ fibers. The relation of vertex PREPse amplitude and pain, or the differential effects of frequency stimulation, is similar to pain-related evoked potential to laser, special electrodes, or contact heat stimulation. The relationship to Aδ was validated by conduction velocity and nerve block. Clinical utility of PREPse compared with CHEPS needs validation in somatosensory pathways lesions., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 by the American Clinical Neurophysiology Society.)

An increasing number of studies have focused on the neural basis of complex mental inferences, which requires an understanding of the recursive nature of thought; however, the precise electrophysiological response to a recursive structure remains unclear. The present event-related potential (ERP) study investigated the recursive structure effect on the neural correlates of visual perspective taking by modifying a third-person visual perspective-taking task. Participants were required to determine how many dots in the presented scenes could be seen from the cued perspective, including the perspectives in the self, other, and recursive (one avatar's belief of another avatar) conditions. The ERP results showed that the N100 and P200 components specific to the recursive-perspective condition showed greater attentional allocation; the N200 component increased in the recursive condition and was related to the conflict process; and larger late slow waves were found in the other- and recursive-perspective conditions compared with those in the self-perspective condition, which reflected the decoupling mechanism. The results suggested that high-order perspective taking requires more attentional resources and conflict processing for further decoupling from the self-perspective., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Decision-making is essential to human functioning, and resolving uncertainty is an essential part of decision-making. Impaired decision-making is present in many pathological conditions, and identifying markers of decision-making under uncertainty will provide a measure of clinical impact in future studies of therapeutic intervention for impaired decision-making., Objective: To describe EEG event-related potentials (ERPs) correlating with decision-making under uncertain conditions when compared with certain conditions., Method: We used a novel card-matching task based on the Wisconsin Card Sorting Test to describe the neural correlates of uncertainty, as measured by EEG, in a group of 27 neurotypical individuals. We evaluated 500-ms intervals in the 2 seconds after card presentation to identify ERPs that are associated with maximal uncertainty compared with maximal certainty., Results: After correcting for multiple comparisons, we identified an ERP in the 500-1000-ms time frame (certain > uncertain, max amplitude 12.73 µV, latency 914 ms) in the left posterior inferior region of the scalp. We also found a P300-like ERP in the left frontal and parietal regions in the 0-500-ms time frame when the individuals received correct versus incorrect feedback (incorrect feedback > correct feedback, max amplitude 1.625 µV, latency 339 ms)., Conclusion: We identified an ERP in the 500-1000-ms time frame (certain > uncertain) that may reflect the resolution of uncertainty, as well as a P300-like ERP when feedback is presented (incorrect feedback > correct feedback). These findings can be used in future studies to improve decision-making and resolve uncertainty on the described markers., Competing Interests: The authors declare no conflicts of interest.

The study investigated the consequences of cross-language activation on the time course of bilingual word recognition. Twenty-two Spanish-English bilinguals and 21 English monolingual controls decided whether visually presented letter strings were English words, while behavioral and event-related potential responses were recorded. The language status of words was manipulated experimentally, such that words were either identical cognates between English and Spanish (e.g. CLUB) or noncognates (e.g. CLOCK). Participants were equally fast in responding to cognate and noncognate words. Bilinguals were more accurate in responding to cognates, whereas monolinguals exhibited higher accuracy in response to noncognates. Critically, bilinguals produced larger P200 followed by smaller N400 responses to cognates than noncognates, whereas monolinguals showed a pattern of reduced N400 responses to cognates. The results of the current study indicate that cross-language activation may not only result in lexical facilitation (indexed by a reduction of the N400 response to cognates) as a result of shared form-meaning associations across languages but also in sublexical inhibition (indexed by a larger P200 response to cognates) as a consequence of cross-language competition among phonological forms. Results support the language-nonselective view of bilingual lexical access and suggest that while lexical facilitation for identical cognates may be observed at most levels of second language proficiency, sublexical inhibition in response to identical cognates may be a marker of advanced levels of proficiency., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: This study seeks to explore the interaction between ignored valence and attended valence in the processing of Chinese emotion words., Methods: The experimental materials utilized in this study consisted of Chinese emotion words. Participants were instructed to observe the words and press a key when presented with target words. Additionally, the electroencephalographic responses of the participants were recorded during the experiment., Results: The results showed that emotional nontarget words elicited greater amplitude of the N170 in the attend-emotion words block compared to the attend-neutral words block. Negative nontarget words produce greater amplitude of the late posterior positivity compared to positive nontarget words. In addition, emotional nontarget words were influenced by both ignored and attended valence, whereby positive nontarget words resulted in larger amplitude of the N170 component in the attend-negative block compared to the attend-neutral block. The modulation pattern for negative nontarget words was evident on the left hemisphere., Conclusion: The findings suggest that emotional nontarget words received greater attentional resources in the attend-emotion words block during the early stages of processing, compared to the attend-neutral word block. Additionally, during the later stages of processing, negative nontarget words were more likely to be processed than positive nontarget words. Overall, these results provide support for the evaluation space model., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: The purpose of this study is to compare cortical motor planning activity during response selection and motor execution processes between individuals with anterior cruciate ligament reconstruction (ACLR) and uninjured controls during a reaction time and response selection task., Methods: Individuals with ACLR ( n = 20) and controls ( n = 20) performed a lateralized choice reaction time (e.g., Go/NoGo) task. Electrocortical activity and reaction time were recorded concurrently using electroencephalography and inertial measurement units. Separate stimulus locked and response-locked event-related potentials were computed for each limb. The lateralized readiness potential (LRP) was computed as the interhemispheric differences between waveforms and the mean LRP area and onset latency were recorded. Active motor threshold was determined using transcranial magnetic stimulation. Differences between groups (ACLR vs control) and limbs (involved vs uninvolved) and the associations between LRP characteristics and response performance (number of errors) were assessed., Results: Participants with ACLR have had smaller LRP area during periods of response selection ( P = 0.043, d = 0.4) and motor execution ( P = 0.015, d = 0.5) and committed more errors in both Go ( P < 0.001, d = 0.8) and NoGo ( P = 0.032, d = 0.5) response conditions. There were no differences in latency of response selection or motor execution. Participants with ACLR had higher active motor thresholds ( P < 0.001, d = 1.3) than controls, which was weakly associated with smaller LRP areas ( r = 0.32-0.42, P < 0.05)., Conclusions: The ACLR group demonstrated greater motor planning and response inhibition during a choice reaction time task. More errant performance also suggests poorer decision making in the presence of a "speed-accuracy" trade-off. Key features of the sample, including lower corticospinal excitability, lend support to an interpretation of widespread cortical inhibition contributing to impairments in response selection and motor execution., (Copyright © 2022 by the American College of Sports Medicine.)

Study Design: A prospective cohort study.Objective: The aim of this study was to compare the somatosensory-evoked potential (SEP) findings of adolescent idiopathic scoliosis (AIS) subjects of different curve severity with age- and gender-matched controls and to evaluate any correlation between the site of the SEP abnormality with cerebellar tonsillar level measured by magnetic resonance imaging (MRI).Summary Of Background Data: Our previous studies showed that a higher percentage of SEP abnormality and cerebellar tonsillar ectopia was present in AIS patients than in normal controls. However, the relationship between the anatomical site of the neurophysiological abnormality and the severity in AIS patients has not been defined.Methods: SEP measurement was conducted on 91 Chinese AIS girls with major right thoracic curve of different curve severity (mild, moderate, severe) and 49 matched normal controls. Waveform characteristics (latency and amplitude) were compared among groups. Specific location of SEP abnormality was identified from tibial to cortical levels. Cerebellar tonsillar ectopia was defined by the previously established reference line between basion and opisthion on MRI.Results: Significant prolonged P37 latency was found on the right side between severe AIS patients and normal controls, while increased inter-side P37 latency difference was found between severe versus moderate, and severe versus normal controls. Cerebellar tonsillar ectopia was detected in 27.3% of severe group, 5.8% to 6.7% in mild and moderate group, but none in normal controls. Abnormal SEP occurred superior to C5 region in all surgical (severe) patients, of whom 58% had cerebellar tonsillar ectopia.Conclusion: AIS patients showed significant prolonged latency and increased latency difference on the side of major curvature. The incidence of SEP abnormality increased with curve severity and occurred above the C5 level. The findings suggested that there was a subgroup of progressive AIS with subclinical neurophysiological dysfunction, associated with underlying neuromorphological abnormalities, which were only detectable by SEP and MRI.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Background: Substrate-based mapping for ventricular tachycardia (VT) ablation is hampered by its inability to determine critical sites of the VT circuit. We hypothesized that those potentials, which delay with a decremental extrastimulus (decrement evoked potentials or DEEPs), are more likely to colocalize with the diastolic pathways of VT circuits.Methods and Results: DEEPs were identified in intraoperative left ventricular maps from 6 patients with ischemic cardiomyopathy (total 9 VTs) and were compared with late potential (LP) and activation maps of the diastolic pathway for each VT. Mathematical modeling was also used to further validate and elucidate the mechanisms of DEEP mapping. All patients demonstrated regions of DEEPs and LPs. The mean endocardial surface area of these potentials was 18±4% and 21±6%, respectively (P=0.13). The mean sensitivity for identifying the diastolic pathway in VT was 50±23% for DEEPs and 36±32% for LPs (P=0.31). The mean specificity was 43±23% versus 20±8% for DEEP and LP mapping, respectively (P=0.031). The electrograms that displayed the greatest decrement in each case had a sensitivity and specificity for the VT isthmus of 29±10% and 95±1%, respectively. Mathematical modeling studies recapitulated DEEPs at the VT isthmus and demonstrated their role in VT initiation with a critical degree of decrement.Conclusions: In this preliminary study, DEEP mapping was more specific than LP mapping for identifying the critical targets of VT ablation. The mechanism of DEEPs relates to conduction velocity restitution magnified by zigzag conduction within scar channels. [ABSTRACT FROM AUTHOR]

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Objective: The Sander illusion and the horizontal-vertical (H-V) illusion are both size and orientation geometric-optical illusions. The Sander geometric figures can be simply regarded as being made up of surrounding frames and inner targeted line segments. Similarly, H-V illusory geometric figures are made up of the targeted line segments. The role of surrounding frames and inner targeted line segments in the perception and cognition of geometric-optical illusions is not well understood., Methods: The time course of event-related potentials (ERP) and the ERP-based standardized low-resolution electromagnetic tomography (sLORETA) source localization were investigated in the Sander illusion and the H-V illusion, which had the same length as the targeted line segments, respectively. The P1, N1, P2, N2 and P3 components of the ERP were focused and measured., Results: The ERP results demonstrated that the existence of surrounding frames in the Sander illusions-induced significant alterations in the P1, N1, P2, N2 and P3 components, compared with the H-V illusion without surrounding frames. In the Sander illusion, different tilted line segments and surrounding frames resulted in significant differences in the P2, N2 and P3 components. The sLORETA results also demonstrated brain activities of source localization as a function of the surrounding frames and the tilted inner line segments., Conclusions: These findings implicate that the perceptual and cognitive processes of the geometric-optical illusions are correlated to the surrounding frames/background, as well as the orientation/direction of inner targeted line segments in geometric figures., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Cognitive impairment is observed in 12% to 56% of stroke patients, and screening for cognitive impairment is often complex and time-consuming, with results dependent on patient compliance. Therefore, there is a need for an objective method to assess cognitive impairment regardless of patient compliance. Objective evaluation methods include electroencephalogram (EEG) and event-related potential (ERP). This study was conducted to assess intra-tester reliability of resting EEG-based spectral features and auditory/visual P300 latency/amplitude in patients with subacute ischemic stroke. Twenty patients with subacute ischemic stroke were included in the study. The resting EEG and P300 wave using an auditory and visual oddball paradigm were measured at baseline and once again in 24 hours. The following electrode positions (10-20 system) were constantly recorded: F3 (Frontal), Fz, F4, C3 (Central), Cz, C4, P3 (Parietal), Pz, P4. DAR (delta/alpha ratio) and BSI (brain symmetry index) were determined using EEG data. F3 and F4, C3 and C4 and P3 and P4 were switched according to the stroke side and classified as affected hemisphere (AH) and unaffected hemisphere (UH) after the evaluation. In ERP, the amplitude and latency of P300 were obtained. In reliability analysis of EEG-based spectral characteristics, significant reliability was observed for DAR (ICC = 0.447), BSldir (ICC = 0.713) and BSIdirtheta (ICC = 0.724) (Table 4). DAR was showed a poor ICC level, and BSIdir and BSIdirtheta had a moderate ICC level. Visual P300 latency showed excellent intraclass correlation coefficient (ICC) in several montages (PUH = 0.972, Pz = 0.945). In 6 montages, auditory P300 latency was reliable, while in 9 montages, visual P300 latency was reliable. In 4 montages, auditory P300 amplitude was reliable, while visual P300 amplitude was reliable in 7. The visual P300 was more reliable than the auditory P300. The ICC values for P300 latency were greater than those for amplitude. Therefore, when ERP is performed on subacute stroke patients, visual has higher reliability than auditory., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

Study Design. Retrospective cohort study. Objective. This study compares time to extubation between major spine surgery patients anesthetized with fentanyl versus sufentanil infusions in combination with propofol. Summary of Background Data. In patients undergoing spinal fusion with intraoperative electrophysiological monitoring of the spinal cord, total intravenous anesthesia with a propofol/opioid combination results in better electrophysiological signals compared with volatile anesthetics. Pharmacokinetic data suggest that total intravenous anesthesia with sufentanil should lead to more rapid emergence from anesthesia than with fentanyl. However, this has never been tested in the spine surgery patient population. Methods. With institutional review board approval, all major spine patients receiving a propofol-based total intravenous anesthesia with fentanyl were compared with those receiving sufentanil. Time to extubation, defined as the time from surgical closure to tracheal extubation, was the study outcome. Relevant demographic, anthropomorphic, anesthetic, and surgical data were collected. Association between type of opioid and time to extubation was tested for statistical significance. Multiple linear regression analysis was used to control for confounders. Results. A total of 167 patients met inclusion criteria (fentanyl = 72, sufentanil = 95). There was no statistically significant difference between the 2 groups in terms of baseline characteristics. Time from surgical closure to extubation in the fentanyl versus sufentanil groups was not statistically different (mean [SD]: 40.2 [26.7] min vs. 45.0 [36.9] min; P = 0.36). On multivariate analysis, total dose of propofol and male sex were associated with increased time to extubation. Conclusion. The use of sufentanil may not reduce time to extubation compared with fentanyl despite its favorable pharmacokinetic profile. Higher doses of propofol and male sex were associated with longer time to extubation and seem to play a greater role than choice of opioid. [ABSTRACT FROM AUTHOR]

Objective: This study examined the immediate effects of noxious and innocuous thermal stimulation intervention on corticomotor excitability for the paretic arm in patients with stroke. Design: Sixteen patients with stroke for more than 3 mos were randomly assigned into the experimental and control groups. All participants received the thermal stimulation protocol on the affected arm for 30 mins. The experimental group received noxious heat (46°C-47°C) and cold (7°C-8°C) stimuli, and the control group received innocuous heat (40°C-41°C) and cold (20°C-21°C) stimuli. Corticomotor excitability was assessed to measure the motor threshold, size of cortical motor output map, and mean motor evoked potentials for the abductor pollicis brevis by focal transcranial magnetic stimulation before and after 30 mins of thermal stimulation intervention program. Results: The findings of transcranial magnetic stimulation revealed a significant increase in map size of the affected hemisphere and mean motor evoked potentials in the experimental group. Moreover, significant differences in the change values of map size (7.0 [7.9] for the experimental group vs. - 1 .7 [2.9] for the control group, P = 0.03) and mean (SD) motor evoked potentials (0.4 [8.9] mV for the experimental group vs. -0 .1 [0.1] mV for the control group, P = 0.03) were found. Conclusions: The preliminary results suggest that the noxious 30 mins of thermal stimulation intervention induced neurophysiologic changes in the motor cortex of the lesioned hemisphere. [ABSTRACT FROM AUTHOR]

Negative evidence may influence category-based inductive reasoning, but the underlying time course of cognitive brain processing is unclear. This study adopted event-related potentials (ERPs) to investigate this effect by manipulating the category type (related vs. unrelated) and argument type (positive vs. negative) in a semantic category-based induction task. The behavioral results showed that, under unrelated conditions, a negative argument produced greater argument strength and shorter reaction time than a positive argument did. Meanwhile, the ERP results found a negative argument elicited larger P300, N400, and slow negative component amplitudes than a positive argument, which could possibly embody the expectation-related processing produced by memory updating, semantic integration, and the more complex inference-driven information integration and interpretation processes and cognitive load in hypothesis generation. This study provides novel evidence on the temporal course of how negative evidence influences argument strength during semantic category-based induction., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Wilson disease (WD) is an inherited disorder of copper metabolism presenting with a variety of symptoms but commonly as a liver or neuropsychiatric disease. Abnormal evoked responses are constantly found among patients with neurologic manifestations and sometimes in patients with hepatic presentation or in presymptomatic siblings. The aim of our study was to assess visual and brainstem auditory evoked potentials (BAEP) in patients with various presentation of WD., Methods: Visual evoked potentials (VEP) were performed in 36 WD patients and BAEP were done in 37 WD patients., Results: Brainstem auditory evoked potentials were normal in patients with isolated hepatic presentation, whereas they were abnormal in 93.5% of patients with neurologic symptoms. There was significant prolongation of the latencies of the III and V waves and of the interpeak III-V and I-V latencies in comparison with the healthy controls (T-test P = 0). Abnormal VEP were observed in 81% of the patients including six of seven neurologically asymptomatic patients. The values of N75, P100, and N145 latencies were significantly longer in all patients than in healthy controls (T-test)., Conclusions: The data showed that VEP and BAEP are more frequently abnormal in WD than previously reported. The abnormal VEP and BAEP even without clinical signs and brain MRI abnormalities point to subclinical involvement of visual and auditory pathways caused by copper toxicity. Because VEP and BAEP are noninvasive and widely available, they should be performed in all patents with WD., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2020 by the American Clinical Neurophysiology Society.)

Background: Individuals with probable Alzheimer disease (AD) may perform below cutoffs on traditional, memory-based performance validity tests. Previous studies have found success using event-related potentials (ERPs) to detect feigned neurocognitive impairment in younger populations., Objective: To evaluate the utility of an auditory oddball task in conjunction with the P3b peak amplitude to distinguish probable AD from simulated dementia., Method: Twenty individuals with probable AD and 20 older healthy controls (HC) underwent an ERP auditory oddball protocol and the Test of Memory Malingering (TOMM). The HC were asked to perform honestly for one condition and to simulate dementia for the other. The individuals with probable AD were asked to perform honestly. The P3b peak amplitude and button press accuracy were collected from each participant and were analyzed to determine their effectiveness in detecting performance validity., Results: The P3b peak amplitude remained stable regardless of behavioral condition in the HC group. When combined with the TOMM Trial 2 score, the P3b peak amplitude further improved the ability to correctly differentiate individuals with probable AD from HC simulating dementia with 100% sensitivity and 90% specificity., Conclusion: The P3b peak amplitude was found to be an effective physiologic measure of cognitive impairment in individuals with probable AD compared with HC simulating dementia. When combined with the TOMM Trial 2 score, the P3b peak amplitude served as a promising performance validity measure for differentiating individuals with probable AD from HC simulating dementia., Competing Interests: The authors declare no conflicts of interest.

Spinal nociception can be facilitated by 5-HT2 receptors in neuropathic pain. We investigated the involvement of glutamate receptors in dorsal neuron hyperexcitation that is promoted by 5-HT2B receptor (5-HT2BR) after spinal nerve ligation (SNL) in the rat. Augmentation of C-fiber-evoked potentials by spinal superfusion with 5-HT2BR agonist BW 723C86 in nerve-ligated rats was impeded by co-administration of NMDA receptor (NMDAR) antagonist D-AP5, but not by mGluR1/5 antagonist AIDA or mGluR2/3 antagonist LY 341495. Evoked potentials were increased by cis-ACPD in nerve-injured rats, irrespective of simultaneous 5-HT2BR blockade by SB204741. In uninjured rats, NMDAR agonist cis-ACPD enhanced evoked potentials in the presence of BW 723C86 but not if administered alone or during exposure to protein kinase C γ (PKCγ) inhibitor peptide. Triple immunofluorescence labelings revealed co-localization of NMDAR and 5-HT2BR in PKCγ-expressing perikarya in lamina II neurons. As a result of SNL, PKCγ was transiently and bilaterally up-regulated in synaptic fraction from dorsal horn homogenates, peaking at day 2 and returning to basal levels by day 9. Chronic blockade of 5-HT2BR with selective antagonist SB 204741 after SNL bilaterally decreased the following: (i) PKCγ up-regulation in synaptic fraction, (ii) phosphorylation of NMDAR subunit NR1 (serine 889) in synaptic fraction, and (iii) co-localization of both PKCγ and phosphorylated NR1 with postsynaptic marker PSD-95. Chronic delivery of SB 204741 bilaterally attenuated thermal and mechanical allodynia occurring after SNL, particularly at day 2 post injury. These findings suggest that transient activation of the PKCγ/NMDAR pathway is critically involved in 5-HT2BR-mediated facilitation in the SNL model of neuropathic pain. [ABSTRACT FROM AUTHOR]

The article discusses research in applied sports science, with a focus on how electromechanical delay (EMD) is affected by a doublet stimulus during submaximal contractions in healthy individuals. Topics include maximal voluntary contraction (MVC), nerve stimulation and evoked potentials, and plantar flexors.

Objectives: We aim to demonstrate intraoperative recording of cerebellar to cortical pathways that have not been previously recorded in humans, though imaged., Methods: We report 2 cases with intraoperative neurophysiologic mapping of cerebellocortical tracts. Direct electrical stimulation of subcortical cerebellum along with recordings of cortical evoked potential and motor muscle recordings was performed during surgery. MR tractography data from healthy participants were used to further illustrate the pathways., Results: Neurophysiologic recordings showed large waveforms of evoked potentials in bilateral electrodes over premotor/motor cortices on stimulation of the dentate nucleus. EMG recordings showed responses in face and neck muscles on stimulation of the dentate nucleus at the motor threshold. We thus demonstrated first-in-human in vivo neurophysiologic evidence of cerebellum to cortex responses through an uncrossed dentatothalamocortical tract to the motor/premotor cortices., Discussion: This technique provides a methodology for the direct mapping of the cerebellum and cerebello-cerebral connections. We hypothesize a direct structural connection from the dentate nucleus to the premotor and motor cortices, as well as to ipsilateral hemibody muscles, acting as a fast route of cerebellar output and back up for immediate motor responses. This will further help explain the modulatory effects of the cerebellum on motor, language, and cognitive functions., (© 2022 American Academy of Neurology.)

Purpose: Multiple sclerosis (MS) is a chronic disorder with a variable course. The aim of our study was to find out whether cognitive event-related potentials are prognostic for patient disability at the 15-year follow-up., Methods: In the observed cohort of patients with MS, we examined the event-related potentials at baseline (2003). Functional status (Expanded Disability Status Scale score) was then assessed 15 years later, and the prognostic model was developed using binary logistic regression analysis. The independent variables included demographic (age, sex, and education), clinical (disability in 2003), radiologic (MRI lesion load), and event-related potentials parameters. The prognostic accuracy of the proposed model was evaluated by calculating the area under the receiver-operating characteristics curve., Results: The study sample consisted of 85 patients with MS. The mean age was 35.5 (SD, 11.2) years, and the median disability score was 3.0 (1-7) in 2003 and 5.0 (1.5-9.5) in 2018. The significant prognostic factors of poor Expanded Disability Status Scale are higher baseline Expanded Disability Status Scale, longer MS duration, and prolonged P300 latency. The sensitivity and specificity of the cutoff at 5.0 for the disability score were 94% and 89%, respectively, with the area under the receiver-operating characteristics curve 0.94 (95% confidence interval, 0.889-0.984; P < 0.001)., Conclusions: The results show that out of event-related potentials, the P300 wave latency is a prognostic of long-term disability progression in patients with MS., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2020 by the American Clinical Neurophysiology Society.)

The testing effect refers to that retrieval practice enhances memory retention more than restudying does. A few previous studies have demonstrated that initial tests could improve memory by increasing recollection, and the depth of encoding could influence the degree of recollection and familiarity involved in retrieval process. The present study aimed to investigate whether the testing effect would be affected by the processing levels. Behavioral results revealed a significant testing effect in the shallow-processing condition, but not in the deep processing. Then, an event-related potential (ERP) experiment was conducted, showing that FN400 that represents familiarity occurred in the testing and restudying conditions with both processing levels, whereas the parietal old/new effect that indicates recollection only did not exist in the restudying with shallow-processing level. These findings revealed that the testing effect would be affected by the processing levels, and the underlying mechanism may be that tests could promote memory by enhancing recollection, which was involved in the deep rather than shallow-processing level during retrieval process. The practical meaning of the present study is that we can use tests to improve memory in a better and more efficient way., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

The article discusses research done on the capability of cinnamophilin to offer neuroprotection against gray and white matter damage and to enhance functional and electrophysiological outcomes following transient focal cerebral ischemia. The study subjects included adult male Sprague-Dawley rats that were subjected to transient middle cerebral artery occlusion. Physiological parameters were examined including neurobehavioral results, somato-sensory-evoked potentials, and arterial blood gases.

Abstract: This is a revision of guidelines, originally published in 2004, for the assessment of patients with neuropathic pain. Neuropathic pain is defined as pain arising as a direct consequence of a lesion or disease affecting the somatosensory system either at peripheral or central level. Screening questionnaires are suitable for identifying potential patients with neuropathic pain, but further validation of them is needed for epidemiological purposes. Clinical examination, including accurate sensory examination, is the basis of neuropathic pain diagnosis. For more accurate sensory profiling, quantitative sensory testing is recommended for selected cases in clinic, including the diagnosis of small fiber neuropathies and for research purposes. Measurement of trigeminal reflexes mediated by A-beta fibers can be used to differentiate symptomatic trigeminal neuralgia from classical trigeminal neuralgia. Measurement of laser-evoked potentials is useful for assessing function of the A-delta fiber pathways in patients with neuropathic pain. Functional brain imaging is not currently useful for individual patients in clinical practice, but is an interesting research tool. Skin biopsy to measure the intraepidermal nerve fiber density should be performed in patients with clinical signs of small fiber dysfunction. The intensity of pain and treatment effect (both in clinic and trials) should be assessed with numerical rating scale or visual analog scale. For future neuropathic pain trials, pain relief scales, patient and clinician global impression of change, the proportion of responders (50% and 30% pain relief), validated neuropathic pain quality measures and assessment of sleep, mood, functional capacity and quality of life are recommended. [Copyright &y& Elsevier]

Abstract: Focused attention typically enhances neural nociceptive responses, reflected electroencephalographically as increased amplitude of pain-evoked event-related potentials (ERPs). Additionally, pain-evoked ERPs are attenuated by hypertension and baroreceptor activity, through as yet unclear mechanisms. There is indirect evidence that these two effects may interact, suggesting that baroreceptor-related modulation of nociception is more than a low-level gating phenomenon. To address this hypothesis, we explored in a group of healthy participants the combined effects of cue-induced expectancy and baroreceptor activity on the amplitude of pain-evoked ERPs. Brief nociceptive skin stimuli were delivered during a simple visual task; half were preceded by a visual forewarning cue, and half were unpredictable. Nociceptive stimuli were timed to coincide either with systole (maximum activation of cardiac baroreceptors) or with diastole (minimum baroreceptor activation). We observed a strong interaction between expectancy and cardiac timing for the amplitude of the P2 ERP component; no effects were observed for the N2 component. Cued stimuli were associated with larger P2 amplitude, but this effect was abolished for stimuli presented during baroreceptor activation. No cardiac timing effect was observed for un-cued stimuli. Taken together, these findings suggest a close integration of cognitive–affective aspects of expectancy and baroreceptor influences on pain, and as such may cast further light on mechanisms underlying mental and physiological contributions to clinical pain. [Copyright &y& Elsevier]

Abstract: Nitroglycerin (NTG), a NO donor, induces an attack in migraine patients approximately 4–6h after administration. The causative mechanisms are not known, but the long delay leaves room for a central effect, such as a change in neuronal excitability and synaptic transmission of various CNS areas involved in pain and behaviour including trigeminal nucleus caudalis and monoaminergic brain stem nuclei. To explore the central action of NTG, we have studied its effects on amplitude and habituation of the nociceptive blink reflex (nBR) and the visual evoked potential (VEP) before, 1h and 4h after administration of NTG (1.2mg sublingual) or placebo (vehicle sublingual) in two groups of 10 healthy volunteers. We found a significant decrease in nBR pain and reflex thresholds both 1 and 4h post-NTG. At the 4h time point R2 latency was shorter (p =0.04) and R2 response area increased (p <0.01) after NTG but not after placebo. Habituation tended to become more pronounced after both NTG and placebo administration. There was a significant amplitude increase in the 5th VEP block (p =0.03) at 1h after NTG and in the 1st block (p =0.04) at 4h. VEP habituation was replaced by potentiation at both delays after NTG; the change in habituation slope was significant at 1h (p =0.02). There were no significant VEP changes in subjects who received sublingual placebo. In conclusion, we found that in healthy subjects sublingual NTG, but not its vehicle, induces changes in a trigeminal nociceptive reflex and an evoked cortical response which are comparable to those found immediately before and during an attack of migraine. These changes could be relevant for the attack-triggering effect of NTG in migraineurs. [Copyright &y& Elsevier]

The most informative neurophysiological techniques available in the neurosurgical intensive care unit are electroencephalograph and somatosensory evoked potentials. Such tools, which give an evaluation of cerebral function in comatose patients, support clinical evaluation and are complementary to neuroimaging. They serve both diagnostic/prognostic and monitoring purposes. While for the former, discontinuous monitoring is sufficient, for the latter, to obtain increased clinical impact, continuous monitoring is necessary. To perform and interpret these examinations in the neurosurgical intensive care unit, both the technician and the neurophysiologist need specific training in the intensive care field. There is sufficient evidence to show that somatosensory evoked potentials are the best single indicator of early prognosis in traumatic and hypoxic-ischaemic coma compared to the Glasgow Coma Score, computed tomography scan and electroencephalograph. Indeed, somatosensory evoked potentials should always be combined with clinical examination to determine the prognosis of coma. Despite widespread use of somatosensory evoked potentials and their prognostic utility in acute brain injury, few studies exist on continuous somatosensory evoked potential monitoring in the intensive care unit. We carried out a pilot study of continuous electroencephalograph-somatosensory evoked potential monitoring in the neurosurgical intensive care unit (traumatic brain injury and intracranial haemorrhage, Glasgow Coma Score <9, intracranial pressure monitoring). All patients stable from a clinical and computed tomography scan point of view showed no significant somatosensory evoked potential modifications, while in the case of clinical deterioration (23%), somatosensory evoked potentials always showed significant modifications. While somatosensory evoked potentials correlated with short-term outcome, intracranial pressure showed a poor correlation. We believe neurophysiological monitoring is an ideal complement to the other parameters monitored in the neurosurgical intensive care unit. Whereas intracranial pressure is simply a pressure index, electroencephalograph-somatosensory evoked potential monitoring reflects to what extent cerebral parenchyma still remains metabolically active during acute brain injury. [ABSTRACT FROM AUTHOR]

Abstract: Although laser pulses activate concomitantly Aδ and C fibres, the corresponding brain evoked responses remain strictly limited to the Aδ component, without any potential consistent with C-fibre activation. To investigate whether this phenomenon depends on the order of arrival to the cortex (“first come first served” hypothesis) or is simply explained by A-to-C inhibition and/or lower energy associated with the desynchronised C-fibre input, we devised an experiment where the physiological order of arrival to the cortex was artificially inverted. Following a conditioning C-pulse, the cortical response to a second laser stimulus was significantly attenuated, whether it was Aδ or C. Thus, a C-volley was able to depress the response to a subsequent Aδ stimulus, in support of the “first come first served” hypothesis. However, the conditioning C-fibre stimulus attenuated significantly more a subsequent C-volley than a subsequent Aδ-volley, indicating that the suppression effect does not depend solely on the order of arrival to the cortex, but also on the ratio of energy per unit time conveyed by the successive inputs. This supports the notion that cortical evoked potentials to laser pulses (and probably to other sensory stimuli) reflect networks detecting rapid energy changes relative to a preceding baseline. The output of such networks should depend both on the time elapsed between successive inputs and on the relative energy per unit time conveyed by successive volleys. Such dedicated networks aimed at detecting energy changes may be related to orienting reactions, and can be dissociated from subjective perception. [Copyright &y& Elsevier]

Clinicians are often expected to project patients' clinical outcomes to allow effective planning for future care. This can be a challenge in patients with moderate to severe traumatic brain injury (TBI) who are often unable to participate reliably in clinical evaluations. With recent advances in computer instrumentation and signal processing, evoked potentials and event-related potentials show increasing promise as powerful tools for prognosticating the trajectory of recovery and ultimate outcome h m the TBI. Short- and middle-latency evoked potentials can now effectively predict coma outcomes in patients with acute TBI. Long-latency event-related potential components hold promise in predicting recovery of higher order cognitive abilities. [ABSTRACT FROM AUTHOR]

Abstract: The human palm has a lower heat detection threshold and a higher heat pain threshold than hairy skin. Neurophysiological studies of monkeys suggest that glabrous skin has fewer low threshold heat nociceptors (AMH type 2) than hairy skin. Accordingly, we used a temperature-controlled contact heat evoked potential (CHEP) stimulator to excite selectively heat receptors with C fibers or Aδ-innervated AMH type 2 receptors in humans. On the dorsal hand, 51°C stimulation produced painful pinprick sensations and 41°C stimuli evoked warmth. On the glabrous thenar, 41°C stimulation produced mild warmth and 51°C evoked strong but painless heat sensations. We used CHEP responses to estimate the conduction velocities (CV) of peripheral fibers mediating these sensations. On hairy skin, 41°C stimuli evoked an ultra-late potential (mean, SD; N wave latency: 455 (118)ms) mediated by C fibers (CV by regression analysis: 1.28m/s, N=15) whereas 51°C stimuli evoked a late potential (N latency: 267(33)ms) mediated by Aδ afferents (CV by within-subject analysis: 12.9m/s, N=6). In contrast, thenar responses to 41 and 51°C were mediated by C fibers (average N wave latencies 485(100) and 433(73)ms, respectively; CVs 0.95–1.35m/s by regression analysis, N=15; average CV=1.7 (0.41)m/s calculated from distal glabrous and proximal hairy skin stimulation, N=6). The exploratory range of the human and monkey palm is enhanced by the abundance of low threshold, C-innervated heat receptors and the paucity of low threshold AMH type 2 heat nociceptors. [Copyright &y& Elsevier]

Background and objective: Changes in the middle latency auditory evoked response following the administration of opioids have been shown. However, it remains unclear as to whether these changes are due to a direct depressant effect of opioids on the middle latency auditory evoked response itself, or an indirect effect on account of their action in attenuating central nervous system arousal associated with noxious stimuli. By comparing changes in the middle latency auditory evoked response in intubated and non-intubated patients, receiving saline or remifentanil in different doses, this study attempts to answer this question. Methods: Fifty-four patients were anaesthetized with isoflurane and nitrous oxide (0.9 MAC) and randomized to 1-6 groups. Groups 1-3 received abolus injection of either saline 0.9%, low-dose remifentanil (1 jig kg I) or high-dose reimfentanil (3 μg kg ) prior to intubation of the trachea. Groups 4-6 were not inrubated following the bolus injection. Results: Pa and Nb amplitudes of the middle latency auditory evoked response increased by 82% and 79% with intubarion in the saline group (P < 0.005) and these changes were not seen in the patients given remifentanil. There was a significant linear trend for the reduction in Pa and Nb amplitude with increasing remifentanil dose (P < 0.05). In the absence of endotracheal intubation remifentanil had no effect on either the amplitudes or latencies of the waves Pa and Nb and there was no effect of dose. For the haemodynamic measurements remifentanil attenuated the pressor response to intubation (P < 0.001) and had a significant dose- related effect (P < 0.001) in the absence of intubarion. Conclusions: We demonstrated an effect of remifentanil on both the middle latency auditory evoked response and haemodynamic changes to endorracheal intubation. For the non-intubated patients there was only an effect of remifentanil on the haemodynamic measurements. This suggests that remifentanil has an effect on the middle latency auditory evoked response in attenuating the arousal associated with intubation of the trachea but has no effect in the absence of a stimulus. [ABSTRACT FROM AUTHOR]

Background and objective: Former studies revealed conflicting information on the usefulness of intraoperative monitoring of visual evoked potentials. This study was designed to evaluate the characteristics of visual evoked potential recording in surgically anaesthetized patients using the modality of steady-state visual evoked potentials. Methods: In 30 cases with non-cranial surgery steady-start visual evoked potentials were recorded in the awake and surgically anaesthetized patient using total intravenous anaesthesia. For stimulation, goggles with red light-emitting diodes at a frequency of 8.5 Hz were used. A two-channel recording with silver cup electrodes at Oz to Fz and Oz to earlobe was used. All tracts were analysed for the presence of the characteristically sinusoidal waveform and amplitudes and latencies of the main peaks were measured. Results: Recordings during surgery demonstrated a minor latency prolongation of 16% and a more pronounced amplitude attenuation of 67% compared to the recordings in the awake patients. These differences were statistically significant (paired t-rest, P < 0.001), In surgically anaesthetized patients steady-scare visual evoked potentials showed a relatively high intra- and interindividual variability. In four of 30 patients completely stable recordings were obtained, whereas in 14 patients identifiable waves were recordable in only less than 50% of the intraoperative traces. Of the total 1360 traces recorded intraoperatively clearly identifiable steady-state visual evoked potentials patterns were present in 56% of the traces. There was no correlation between the magnitude of the evoked potential amplitude and its stability in intraoperative recordings. Conclusions: We conclude from this studs, that steady-stare visual evoked potential recordings in the surgically anaestherized patient appeared to be more stable compared to our earlier findings using transient visual evoked potentials. However, further efforts are necessary to improve the stability of the recordings during surgery and thus allow for a inure reliable intraoperative monitoring of visual pathways in routine clinical practice. [ABSTRACT FROM AUTHOR]

In this review paper, the authors critically analyse the use of a number of depth of anaesthesia monitors in light at the most recent literature and their own clinical experience. There appears to be increasing evidence that anaesthesia depth monitors reduce the incidence of unexpected intraoperative awareness and also that they improve the quality of anaesthesia. Proper use of these monitors necessitates background knowledge about the physiology of the loss of consciousness, the type of variable recorded arid processed by the monitoring devices, the factors that might interfere with recording and the limits of use. The information provided by anaesthesia depth monitors is detailed and relationships with clinical practice are established to provide the reader with key features for optimal use of those monitors and correct interpretation of data. Practitioners and patient's knowledge and expectations regarding this matter, as well as the cost-benefit relationship are also discussed. [ABSTRACT FROM AUTHOR]

Hitherto, neither desflurane nor sevoflurane, with similar physicochemical properties, have been compared with regard to their effects on the central nervous system. We compared the effects of desflurane and sevoflurane on electrical cortical activity and sensory transmission at two anaesthetic concentrations in patients undergoing hysterectomy. Both volatile agents induced a concentration-related increase of power in the slow delta-band and a concomitant decrease of power in the fast beta-domain. There was a close correlation with regard to the decrease in beta-power and heart rate (r2 = 0.988) and systolic blood pressure (r2 = 0.952) following both agents. Desflurane and sevoflurane had little effect on the early N20-peak, but affected the late N100-peak. There was a concentration-related increase in latency and a depression of amplitude height. Changes were not significantly different between both agents. Both desflurane and sevoflurane possess a similar profile with regard to their hypnotic effects and a similar outline in depressing propagation within the sensory nervous system. Cortical nervous effects are mirrored closely in heart rate and systolic blood pressure. [ABSTRACT FROM AUTHOR]

Background and objective: Previous studies have shown existence of inconsistent data concerning the use of auditory-evoked potential (AEP) and electroencephalogram (EEG) changes to measure the depth of anaesthesia in regimens involving the use of opioids. The present studies characterize the effects of fentanyl on those responses in rats. Methods: The effects of a bolus of fentanyl (6-l0 μ kg[sup-1] intravenously) alone or following naloxone (l00 μ kg[sup-1] intravenously) were examined using bruin responses in rats during light anaesthesia with either propofol (20—30 mg kg[sup-1] h[sup-1] ) or isoflurane (0.8%). Electrophysiological data were recorded using silver ball electrodes. The rats' tracheas were intubated and a femoral artery cannula was inserted to monitor blood pressure. Body temperature, respiratory and pulse rate, and pedal withdrawal data were also collected. Parameters measured before and following administration of naloxone and fentanyl or of fentanyl alone were compared using repeated-measures ANOVA. Results: Fentanyl significantly increased the latency of the major peak from the AEP during propofol and isoflurane anaesthesia (F = 13.2 and 13.5 respectively; P < 0.05) and the amplitude differential between two waveform complexes, and the second differential index (F = 28.3 and 57.2, respectively; P < 0.01). The spectral edge frequency and median frequency from the EEG tended to increase. These effects were abolished by the prior administration of Naloxone. Conclusions: These excitatory effects were inconsistent with the classical concept of brain activity depression indicating a deepening of anaesthesia. [ABSTRACT FROM AUTHOR]

The role of operant conditioning for the development and maintenance of chronic pain was examined in 30 chronic back pain patients (CBP) and 30 matched healthy controls. Half of each group was reinforced for increased, half for decreased pain reports while EEG, EOG, heart rate, skin conductance and muscle tension levels were recorded. Both groups showed similar learning rates, however, the CBP patients displayed slower extinction of both the verbal and the cortical (N150) pain response. In addition, the CBP group displayed prolonged elevated electromyogram levels to the task. These data suggest that CBP patients are more easily influenced by operant conditioning factors than healthy controls and this susceptibility may add to the maintenance of the chronic pain problem. [Copyright &y& Elsevier]

Summary: This review summarizes main applications of event-related potentials (ERPs) to the study of cognitive processes in persons with neurodevelopmental disorders, for whom traditional behavioral assessments may not be suitable. A brief introduction to the ERPs is followed by a review of empirical studies using passive ERP paradigms to address three main questions: characterizing individual differences, predicting risk for poor developmental outcomes, and documenting treatment effects in persons with neurodevelopmental disorders. Evidence across studies reveals feasibility of ERP methodology in a wide range of clinical populations and notes consistently stronger brain-behavior associations involving ERP measures of higher-order cognition compared with sensory-perceptual processes. The final section describes the current limitations of ERP methodology that need to be addressed before it could be used as a clinical tool and highlights the needed steps toward translating ERPs from group-level research applications to individually interpretable clinical use., Competing Interests: The author has no conflicts of interest to disclose., (Copyright © 2021 by the American Clinical Neurophysiology Society.)

Summary: The definition of consciousness has been the subject of great interest for many scientists and philosophers. To better understand how evoked potentials may be identified as biomarkers of consciousness and recovery, the different theoretical models sustaining neural correlates of consciousness are reviewed. A multimodal approach can help to better predict clinical outcome in patients presenting with disorders of consciousness. Evoked potentials are inexpensive and easy-to-implement bedside examination techniques. Evoked potentials are an integral part of prognostic evaluation, particularly in cases of cognitive motor dissociation. Prognostic criteria are well established in postanoxic disorders of consciousness, especially postcardiac arrest but are less well determined in other etiologies. In the early examination, bilateral absence of N20 in disorder of consciousness patients is strongly associated with unfavorable outcome (i.e., death or unresponsive wakefulness syndrome) especially in postanoxic etiologies. This predictive value is lower in other etiologies and probably also in children. Both N20 and mismatch negativity are proven outcome predictors for acute coma. Many studies have shown that mismatch negativity and P3a are characterized by a high prognostic value for awakening, but some patients presenting unresponsive wakefulness syndrome also process a P3a. The presence of long-latency event-related potential components in response to stimuli is indicative of a better recovery. All neurophysiological data must be integrated within a multimodal approach combining repeated clinical evaluation, neuroimaging, functional imaging, biology, and neurophysiology combining passive and active paradigms., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Clinical Neurophysiology Society.)

Background and Purpose: The aim of this study was to verify the validity of the proportional recovery model in view of the ceiling effect of the Fugl-Meyer Assessment., Methods: We reviewed the medical records of patients enrolled in the Korean Stroke Cohort for Functioning and Rehabilitation between August 2012 and May 2015. Recovery proportion was defined as the actual change in Fugl-Meyer Assessment score of the upper extremity between 7 days and 6 months poststroke, relative to the initial neurological impairment. We then used logistic regression to identify clinical factors attributable to a ceiling effect of the Fugl-Meyer Assessment score of the upper extremity and propensity score matching to verify the validity of the proportional recovery rule., Results: We screened 10 636 patients and analyzed 849 patients (mean age, 65.4±11.9 years; female, 320 [37.7%]) with first-ever ischemic stroke. We found, through logistic regression analysis, that a one-unit increase in the initial neurological impairment and the age at stroke onset affected the odds ratio (1.0386 and 0.9736, respectively) of achieving the full Fugl-Meyer Assessment score of the upper limb at 6 months poststroke. We also demonstrated, through propensity score matching, that the difference in initial neurological impairment of the upper extremity resulted in discrepancy of the recovery proportion (0.92±0.20 [0–1] versus 0.81±0.31 [0–1], P<0.001)., Conclusions: We demonstrated that the ceiling effect of the Fugl-Meyer Assessment score of the upper extremity is pronounced in patients with mild initial motor deficits of the upper extremity and that the recovery proportion varies according to the initial motor deficit of the upper limb using logistic regression analysis and propensity score matching, respectively. These results suggest that the proportional recovery model is not valid.