Objective This preliminary study examined the efficacy of cathodal transcranial direct current stimulation (tDCS) targeting the medial prefrontal cortex (mPFC) in reducing symptom severity, enhancing cognitive flexibility, and modulating brain-derived neurotrophic factor (BDNF) levels in individuals with obsessive-compulsive disorder (OCD). Methods A double-blind, randomized, sham-controlled trial was conducted with 20 patients meeting DSM-V criteria for OCD, of whom 15 completed the intervention and were included in the final analysis. Participants received cathodal mPFC-tDCS (2 mA, 20 min, 10 sessions) or sham stimulation. Symptom severity (Y-BOCS), cognitive flexibility (task-switching), salivary BDNF, and frontal alpha activity (qEEG at Fz) were measured at baseline, post-treatment, and follow-up. Results The tDCS group exhibited greater reductions in Y-BOCS scores over time (F(2, 26) = 12.562, p < 0.001, partial η2 = 0.425). Task-switching performance improved in the experimental group compared with controls (F(2, 26) = 20.351, p < 0.001, partial η2 = 0.531). Salivary BDNF levels increased significantly in the tDCS group at follow-up (F(2, 16) = 6.086, p = 0.01, partial η2 = 0.432). Trends toward normalization of frontal alpha activity were observed, but did not reach statistical significance. Conclusions Cathodal mPFC-tDCS was associated with reduced OCD symptom severity, improved cognitive flexibility, and increased salivary BDNF. These preliminary findings warrant replication in larger controlled samples. Significance This study extends previous tDCS research in OCD by integrating clinical outcomes with cognitive performance and a peripheral marker of neuroplasticity. It provides preliminary support for mPFC-targeted tDCS as a potential intervention for OCD.
Objective:Somatosensory evoked fields (SEF) recorded using magnetoencephalography enable non-invasive measurement of the cortical activity within the afferent somatosensory pathway. Because MRI studies suggest that delayed myelination and damage to the white matter contribute to adverse effects on neurological development in preterm infants, early functional markers of brain maturation are of particular interest. Methods:In this single-center pilot study, SEFs were recorded using tactile stimulation in 13 preterm infants examined at 36 weeks' gestational age (GA) and 8 term infants examined at 40 weeks' GA. Latencies to the first cortical deflection in the somatosensory cortex were analyzed and compared across gestational ages at recording and between very preterm (26-31 weeks of GA at birth) and moderate/late preterm infants (32-36 weeks GA). Results:SEF waveforms were obtained in all infants. Latencies were longer in preterm infants at 36 weeks' GA compared to term infants at 40 weeks' GA and decreased significantly with advancing GA. No significant latency differences were found between very preterm and moderate/late preterm infants at 36 weeks' GA. Conclusions:MEG-based SEF recording is feasible in preterm infants at 36 weeks' GA. SEF latency did not provide evidence of a significant delay in somatosensory maturation in very preterm compared with moderate/late preterm infants and does not support the hypothesis of a delayed myelination in very preterm infants. Significance:Although limited by sample size, single time-point measurements, and lack of magnetic resonance imaging (MRI), our study lays a foundation for future MEG investigations of premature infants in early life.
Objective:Alterations in autonomic nervous system activity - measured by heart rate variability (HRV) and heart rate (HR) - have been proposed as a relevant biopsychological mechanism in several psychiatric disorders. However, only few studies have examined these parameters in OCD, and evidence from pediatric samples is particularly limited. The aim of this study was to investigate autonomic activity in pediatric OCD. Methods:A five minute resting state electrocardiogram was recorded in adolescents with OCD (n = 64) and age- and IQ-matched healthy controls (HC, n = 52). Autonomic activity was compared using the logarithmized root mean square of differences between successive R-R intervals (logRMSSD), the logarithmized high-frequency HRV (logHF-HRV), the percentage of adjacent NN intervals differing from each other by more than 50 ms (pNN50) and HR. Associations with psychotropic medication status and symptom severity were assessed. Results:Adolescents with OCD showed lower logRMSSD and higher HR than HC, whereas logHF-HRV and pNN50 did not differ between groups. No associations were found between cardiac measures and OCD symptom severity. Exploratory subgroup analyses suggested lower logHF-HRV and logRMSSD in medicated adolescents with OCD. Conclusions:Our findings add to evidence for altered autonomic activity in pediatric OCD, reflected by elevated HR and lower RMSSD. The observed reduction in HRV did not increase with greater symptom severity and appeared most pronounced among medicated adolescents with OCD. Significance:The autonomic imbalance observable in adolescents with OCD is common across anxiety disorders and has been linked to cardiovascular risk.
Objective:Antagonist co-contraction triggered by voluntary agonist command in spastic paresis is poorly understood. Using an isometric ankle paradigm designed to minimize movement-related stretch reflexes, we aimed to characterize the severity, modulation, and neurophysiological origin of spastic co-contraction. Methods:Thirteen subjects with chronic hemi/paraparesis (n = 14 limbs) were seated with the ankle at 90° dorsiflexion, and performed submaximal then maximal isometric voluntary ankle plantar- and dorsiflexion efforts, with the knee flexed then extended (gastrocnemii slack then stretched). Surface and intramuscular EMG recordings (the latter using hook wire electrodes) from agonist and antagonist muscles were combined with ankle torque measurements. Co-contraction severity was classified as absent, no antagonist EMG activity during agonist effort; mild, presence of antagonist EMG activity without torque reversal; or severe, antagonist EMG activity associated with torque in the unintended direction. Results:Antagonist co-contraction occurred in all limbs during dorsi- and plantar flexor efforts. Its severity increased from submaximal to maximal efforts, whether in knee flexion (p = 0.046, Wilcoxon) or knee extension (p = 0.014). Severe plantar flexor co-contraction was more prevalent with the knee extended than flexed (64% vs 0%; p = 0.004, McNemar). Antagonist activity preceded agonist activation in 18% of efforts. In some intramuscular recordings, the first motor unit recruited in co-contractions was identified as that first-recruited when the same muscle was contracted voluntarily as agonist. Conclusions:Spastic co-contraction likely reflects misdirected descending supraspinal command, potentiated by stretch-related peripheral afferent signals.Significance. Spastic co-contraction is an effort-dependent, stretch-sensitive phenomenon distinct from spasticity, and can severely impair force generation in spastic paresis.
Objective:Focal rhythmic delta activity (RDA) is a subtype of lateralized RDA (LRDA). Although several studies have compared scalp and intracranial electroencephalography (EEG) recordings to determine whether LRDA observed on scalp EEG reflects epileptic abnormalities occurring intracranially during the acute phase, to our knowledge, no studies have examined focal RDA. Therefore, we investigated the extent to which focal RDA on scalp EEG during the acute phase reflects epileptic activity observed on intracranial EEG. Methods:We retrospectively reviewed cases with simultaneous intracranial and scalp EEG (January 2003-August 2024). Patients who developed an intracranial hematoma during electrode placement were identified and included. For each case, we evaluated whether RDA, spikes, polyspikes, electrographic seizures (ESz), electrographic status epilepticus (ESE), and high-frequency oscillations (HFOs) observed on intracranial EEG near the hematoma were reflected on scalp EEG in terms of appearance, timing, frequency, and amplitude. Results:Of the 116 patients, six developed intracranial hematoma and were included in the analysis. Focal RDA was observed on scalp EEG in all six cases, whereas intracranial RDA appeared earlier than focal RDA on scalp EEG. In all cases, spikes and polyspikes were superimposed on the RDA in the intracranial EEG, whereas these findings were observed on scalp EEG in only three cases. ESz, ESE, and HFOs were observed in all intracranial recordings but were not detected on scalp EEG. Significance:Focal RDA observed on scalp EEG during the acute phase may reflect growing epileptic activity and serve as a potential target for antiseizure medication therapy.
Objective In a procedural learning environment, trainees acquire skills for managing life-threatening emergencies, a context that inherently elicits stress. While moderate stress can enhance memory consolidation, excessive stress (distress) may impair learning and performance. Here we elucidated the neurophysiological effects of stress on learners during a procedural learning task. Methods We examined the effects of stress on learning by assessing EEG functional connectivity (FC) in medical trainees during endotracheal intubation. The cohort comprised medical trainees who were monitored at baseline (rest) and during two high-fidelity simulation scenarios: a calm condition and a stressful condition (intubation during anesthesia induction). Concurrent data were collected, including heart rate, eye blinks and self-reported measures of perceived stress and cognitive load. Results High-fidelity simulation reliably provokes a physiological stress response, predominantly mediated by sympathetic nervous system activation. Across conditions, FC increased relative to baseline, indicating heightened neural network synchronization during task engagement. Notably, under the stressful condition, FC was further elevated compared with the calm scenario, suggesting that stress within a defined range may enhance neural communication efficiency and learning capacity. Conclusions These findings imply a potential neurophysiological signature of stress that could be leveraged to design personalized educational interventions, calibrating stress levels to optimize learning while mitigating deleterious effects. Significance The study demonstrates the feasibility of using real-time EEG to monitor stress-related neural dynamics in medical trainees and underscores the importance of integrating neurophysiological insights into the development of training environments.
The recent position statement by the International Federation of Clinical Neurophysiology (IFCN) provides a critical roadmap for the implementation of artificial intelligence (AI) in clinical neurophysiology. AI has immense potential to augment existing practice, but careful navigation is required to overcome challenges to efficient and ethical clinical deployment. The challenges - including fragmented workflow, opaque governance, ethical liabilities and automation bias - are critically reviewed and strategies are proposed to ensure the seamless transition to widespread implementation within real-world clinical neurophysiology practice.
Objective:To quantify the effect of acute caffeine intake on fasciculation frequency in healthy adults using muscle ultrasound and to explore differences between muscle groups and age categories. Methods:In this monocentric intraindividual pre-post study, 54 neurologically healthy adults aged 20-50 years underwent ultrasound examination of six muscles: biceps brachii, first dorsal interosseous, abductor pollicis brevis, vastus medialis, gastrocnemius caput laterale, and abductor hallucis. Fasciculations were recorded for 120 s per muscle at baseline and repeated 45 min after administration of a single oral caffeine dose of 2 mg/kg body weight. Changes in fasciculation frequency were analyzed within individuals and compared between participants aged 20-34 and 35-50 years. Results:Acute caffeine intake was associated with an increase in fasciculation frequency across most examined muscles. The largest increases were observed in the gastrocnemius and abductor hallucis, whereas changes in the vastus medialis were minimal. Upper limb muscles showed moderate increases in fasciculation activity. Age-related differences were identified: younger participants demonstrated relatively greater increases in upper limb muscles, while older participants showed more pronounced increases in lower limb muscles. Although interindividual variability was present, the overall pattern suggested enhanced motor unit excitability following caffeine intake. Conclusions:Acute caffeine intake appears to increase ultrasound-detectable fasciculation frequency in healthy adults. The effect is muscle-dependent and may vary with age. Significance:Recent caffeine consumption may influence the detection and interpretation of fasciculations during neuromuscular assessment. Consideration of caffeine intake before muscle ultrasound or electromyographic examinations may improve diagnostic accuracy and reduce misinterpretation of benign fasciculation activity. (218 words).
Objective:Falls are common in individuals with dementia and pose a significant problem in acute hospital care. Aging and dementia affect functional brain networks including the default mode network (DMN), dorsal attention network (DAN) and salience network (SAN). The DAN and SAN are essential for the rapid detection of responses to unexpected stimuli. We hypothesize that global efficiency within these networks is reduced in patients with dementia who experience falls compared with those who do not. Methods:We analyzed 347 inpatients with dementia from a neurological clinic in Vienna, Austria. Of 153 available EEGs, only those with normal findings were included. FC was calculated using the phase-locking-value across delts, theta, alpha, and beta bands. The characteristic path length of the DAN, SAN and DMN was computed. Results:Fallers showed reduced global efficiency in the DAN. FC between the right rostral middle frontal gyrus and left middle frontal gyrus was decreased in delta, theta, and alpha bands - regions involved in visual stimulus processing and executive control. Conclusions:Reduced DAN connectivity may impair the ability to respond to unexpected stimuli, increasing fall risk in individuals with dementia. This supports the role of attention network dysfunction in motoric cognitive risk syndrome. Significance:Falls are a significant problem in dementia, not well understood so far. Identifying network level dysfunction in dementia related falls offers a novel biomarker for risk stratification and possible targets for future interventions.
Objective:EEG is an essential diagnostic tool in epilepsy. Many patients with intellectual disability and epilepsy reside in residential care facilities and do not have access to EEG, as the modality is not available on-site. Additionally, due to poor cooperation, transporting these patients to specialized hospital-based EEG centers is often difficult or impossible resulting in lack or delayed diagnostic evaluation. Mobile, point-of-care EEG systems, with electrodes that can be easily applied outside the hospital by caregivers without formal training in EEG recording, have the potential to bridge this diagnostic gap. Methods:In this prospective multicenter study, we assessed the feasibility and clinical utility of a point-of-care EEG system in residential care facilities. EEG electrodes were applied by local personnel without prior training in EEG recording. Data was uploaded to a secure cloud platform and remotely interpreted by experts. Results:We recruited 25 participants. EEG recording could be completed in 22 participants. The recordings were clinically interpretable in 17 participants and provided complete answers to the referrals in 11 participants. No technical failures of the EEG device or data transmission were observed. Conclusions:Our results demonstrate the feasibility and clinical utility of point-of-care mobile EEG for the diagnosis of epilepsy in residential care facilities. Significance:Point-of-care mobile EEG has the potential to improve equity in access to neurophysiological diagnostics.
Objective Microstates derived from EEG amplitude and connectivity states from EEG phase examine distinct aspects of the brain's dynamic organization. However, it is unclear how sensitive they are to changes in functional connectivity in Alzheimer's disease (AD). We examined pre- and post-task alterations of brain activity in AD patients to compare the ability of microstates and connectivity states to capture disease-related network dysfunction. Methods Resting-state EEG (RS-EEG) was recorded before and after a memory task in fifteen patients with AD and fifteen healthy controls. During the memory task, either low-intensity repetitive transcranial magnetic stimulation (rTMS) over the parieto-occipital region or sham stimulation was applied. We quantified microstates and phase-based connectivity states in the alpha frequency range from the RS-EEG. Results While microstates showed task-related alterations in healthy controls only, connectivity states were more sensitive to alterations in the AD group. rTMS appeared to reduce these task-related alterations in connectivity states. Connectivity states indicated a shift towards lower, more diffuse connectivity in AD patients. Connectivity states were correlated with memory task performance and amyloid-beta levels in the AD group. Conclusions Connectivity states indicated decreased task-related network stability in AD patients, which correlated with memory task performance. The findings support the neural efficiency hypothesis, which states that more efficient brain network optimization during tasks is linked to better performance. Significance Given the progressive decline of alpha power in AD patients, phase-based connectivity states provide valuable complementary information to microstates and may serve as a biomarker for assessing large-scale network alterations in relation to disease progression.
Objective:Sensorimotor beta activity provides a real-time marker of motor-network state, but whether electroencephalography (EEG)-derived timing of peripheral stimulation can modulate ipsilateral motor output remains unclear. We tested whether EEG-timed neuromuscular electrical stimulation (NMES) alters ipsilateral transcranial magnetic stimulation (TMS)-evoked motor responses in humans. Methods:Twenty right-handed healthy participants completed four sessions of 24 Hz NMES applied to the left extensor digitorum communis. NMES train onset was triggered at four nominal timing conditions derived from the ongoing 24 Hz EEG component over the ipsilateral sensorimotor cortex. Ipsilateral motor output was assessed with TMS before and after each intervention. Peak-to-peak amplitudes of ipsilateral TMS-evoked motor responses were analyzed using a linear mixed-effects model. Results:EEG-timed NMES produced timing-dependent and muscle-specific changes in ipsilateral TMS-evoked motor response amplitudes. Flexor responses were suppressed across timing conditions, whereas extensor responses increased selectively in one EEG-derived timing condition. This response pattern dissociated generalized antagonist suppression from timing-specific facilitation of the stimulated extensor motor output. Conclusions:Ipsilateral TMS-evoked motor responses are sensitive to the temporal alignment between peripheral input and ongoing EEG-recorded ipsilateral sensorimotor activity. Significance:EEG-timed NMES provides a human neurophysiological framework for probing state-dependent sensorimotor coupling and may inform future closed-loop peripheral neuromodulation strategies.
Objective:Surgery and anesthesia can be associated with postoperative neurological injury, especially in individuals with diminished cognitive reserve. Timely identification of at-risk patients enables deployment of preventive strategies. Despite consistent recommendations, perioperative cognitive risk assessment remains largely overlooked. We explored which dynamic electroencephalogram (EEG) patterns are correlated with cognitive subdomains significantly affected by surgery and anesthesia. Methods:This was a secondary analysis of two prospective observational studies that included patients undergoing elective laparoscopic abdominal or pelvic surgery under general anesthesia. Cognition was assessed using the Mini-Mental State Exam, 2nd edition (MMSE-2) and the Montreal Cognitive Assessment (MoCA) within one week before and up to 48 h after surgery. Frontal EEG was recorded pre-induction to extubation. Cognitive subdomains and EEG changes were explored using linear regression and accuracy analyses. Results:Data were obtained from 23 surgical patients (median [IQR] age, 63 [16] years; 52% female). Auditory-verbal delayed recall (MMSE-2, p = 0.001 AUC = 0.76 [0.62-0.89]; MoCA, p < 0.001 AUC = 0.75 [0.6-0.89]) and processing speed (MMSE-2, p < 0.001 AUC = 0.85 [0.72-0.95]) were significantly affected postoperatively. Delta power at the end of maintenance, changes in theta, alpha power, aperiodic slope, offset were correlated with processing speed changes. Conclusion:Dynamic EEG patterns were correlated with processing speed changes. Integrating EEG into perioperative risk assessment may contribute to early identification of vulnerability. Significance:This study demonstrates the correlation between changes in perioperative EEG and cognitive subdomains.
Background:Intraoperative somatosensory evoked potential (SSEP) monitoring is widely employed during lumbar spine surgery, yet its diagnostic accuracy remains incompletely characterised for contemporary minimally invasive approaches. Objective:To evaluate the diagnostic accuracy of intraoperative SSEP changes for predicting postoperative neurologic deficits and assess whether reversibility differentially influences performance. Methods:Systematic review and meta-analysis (PROSPERO: CRD422026135172) restricted to studies published after the Chang et al. (2021) search cutoff (October 2019 to January 2026); five studies (1017 patients). DerSimonian-Laird random-effects logit models estimated pooled sensitivity, specificity, and diagnostic odds ratio (DOR); subgroup analyses by reversibility. Heterogeneity: Cochran Q and I2 with 95% CIs; quality: QUADAS-2.Results: Pooled sensitivity 36.4% (95% CI: 10.7-73.2%); specificity 91.7% (95% CI: 74.6-97.6%); DOR 5.22 (95% CI: 2.17-12.52); I2 = 0.0%. Irreversible changes: DOR 22.12 (95% CI: 3.06-159.7); reversible: DOR 0.69 (95% CI: 0.18-2.66; P = .594). Positive likelihood ratio (LR+) 4.39 (post-test probability 16.9%); negative likelihood ratio (LR-) 0.69 (3.1%). Deeks funnel test P = .819. Conclusions:Across five contemporary lumbar surgery studies (1017 patients; 2019-2026), SSEP monitoring is highly specific (91.7%) but only moderately sensitive (36.4%) for neurologic deficits. Irreversible changes carry greater diagnostic weight (DOR 22.12; 95% CI: 3.06-159.7) than reversible changes (DOR 0.69; 95% CI: 0.18-2.66). Monitoring modality should match the neural structures at risk; adjunct MEP and EMG are recommended where motor root injury predominates. Significance:Procedure-specific SSEP diagnostic accuracy estimates for contemporary lumbar surgery support a context-dependent approach; the greater diagnostic weight of irreversible versus reversible changes (DOR 22.12 vs 0.69) has direct intraoperative implications.
Objective:To evaluate the feasibility and clinical utility of arcuate fasciculus cortico-cortical evoked potentials (AF-CCEP) and axono-cortical evoked potentials (AF-ACEP) during perisylvian supratentorial tumor surgery, and examine whether morphology changes serve as electrophysiological biomarkers of postoperative language function. Methods:We analysed 19 patients with tumors involving or adjacent to the arcuate fasciculus across multiple tertiary centers. AF-CCEPs were elicited by monophasic stimulation toward the inferior frontal gyrus and recorded over the middle or posterior superior temporal gyrus; AF-ACEPs were obtained via subcortical bipolar stimulation. Primary outcomes explored N1 morphology pre- and post-resection, with subgroup analyses by tumor grade, location, montage, and anesthesia. Results:822 AF-CCEPs and 134 AF-ACEPs were acquired intraoperatively; 133 and 37 matched recordings were included for analysis, respectively. Post-resection N1 peak amplitude increased cohort-wide, while onset latency remained stable. One patient demonstrated signal loss associated with postoperative aphasia. AF-ACEP amplitudes were higher under general anesthesia, in higher-grade tumors, and with proximity to the AF on tractography. Conclusions:AF-CCEP and AF-ACEP are feasible intraoperative adjuncts, with signal degradation associated with language morbidity. Post-resection amplitude increases may reflect intact AF conduction with increased cortical excitability following tumor removal. Significance:When awake craniotomy is contraindicated, AF-CCEP and AF-ACEP may represent a viable alternative for monitoring AF integrity and reducing postoperative language morbidity.
Objective: To provide preliminary reference data for thermal quantitative sensory testing (QST) at the foot dorsum in healthy Vietnamese adults and to examine associations with demographic and metabolic variables. Methods: This cross-sectional study included 68 healthy Vietnamese adults (23-80 years). Participants were screened to exclude diabetes and prediabetes according to ADA 2024 criteria. Cold Detection Threshold (CDT), Warm Detection Threshold (WDT), and Heat Pain Threshold (HPT) were assessed bilaterally at the foot dorsum using the Q-Sense device and the Method of Limits protocol. Reference intervals (2.5th-97.5th percentiles) were estimated using non-parametric methods. Multivariable linear regression was used to evaluate associations with age, sex, BMI, LDL-C, triglycerides, and HbA1c. Results: Bilateral symmetry supported the use of averaged bilateral values. Age was independently associated with all QST parameters (CDT β = -0.0299; WDT β = 0.0801; HPT β = 0.0739; all p < 0.001). In the reduced model, BMI was associated with CDT (β = 0.0929, p = 0.030), but this was not observed in the full model. LDL-C was associated with WDT in both models (β = 0.0122, p = 0.007; β = 0.0121, p = 0.011). Sex was not consistently associated with any parameter. Conclusions: This study provides preliminary reference data for thermal QST in a Vietnamese population. Age was the most determinant of thermal thresholds. LDL-C was associated with warm detection thresholds, while BMI was not significant in the full model. Significance: These data may support interpretation of thermal QST in clinical practice.
