Journal Of Clinical Neurophysiology[JOURNAL]
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200 papers
Low-Frequency Repetitive Nerve Stimulation in Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome.
Ding Q, Wu S, Hu Y … +4 more , Wu Y, Tan Y, Cui L, Guan Y
J Clin Neurophysiol · 2026 Jun · PMID 42274368 · Publisher ↗
OBJECTIVE: Lambert-Eaton myasthenic syndrome (LEMS) and myasthenia gravis (MG) exhibit distinct decrement patterns in low-frequency repetitive nerve stimulation. While a delayed nadir in LEMS is well-documented, we ident...
OBJECTIVE: Lambert-Eaton myasthenic syndrome (LEMS) and myasthenia gravis (MG) exhibit distinct decrement patterns in low-frequency repetitive nerve stimulation. While a delayed nadir in LEMS is well-documented, we identified additional unique patterns. This study systematically compared low-frequency repetitive nerve stimulation features between the two conditions using prolonged protocols. METHODS: We retrospectively analyzed 20 patients with LEMS (March 2019-August 2025) and 34 age-matched patients with MG (April 2023-August 2025). All subjects underwent low-frequency repetitive nerve stimulation (3 Hz, 5 Hz; 25 stimuli per train) on the abductor digiti minimi and trapezius muscles. Key parameters included compound muscle action potential nadir position and postnadir amplitude recovery. RESULTS: As previously reported, patients with LEMS had significantly lower baseline compound muscle action potential amplitudes than patients with MG. In MG, 90.9% of tested muscles showed a compound muscle action potential nadir at the 4th or 5th response. By contrast, 65.5% of LEMS muscles exhibited a delayed nadir between the 7th and 10th responses. Notably, 24.1% of LEMS muscles displayed a nadir at waves 4 to 5 followed by substantial amplitude recovery. In this subgroup, the amplitude difference between the nadir and the 10th or 25th response showed high sensitivity and specificity in differentiating LEMS from MG. Furthermore, 10.3% of LEMS muscles exhibited direct facilitation, characterized by an amplitude increase without an initial decrement. CONCLUSIONS: In addition to the previously reported delayed decrement, we identified two additional abnormal low-frequency repetitive nerve stimulation patterns in LEMS: early decrement with postnadir recovery and direct facilitation. These three LEMS-specific patterns differ from those observed in MG and may aid in the differential diagnosis of MG and LEMS.
Interpreting Motor Evoked Potential and D-wave Changes During Intramedullary Spinal Cord Tumor Surgery.
Choi J
J Clin Neurophysiol · 2026 Jun · PMID 42246617 · Publisher ↗
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Scalp EEG Signals: Generators and Dipoles.
Beniczky S, Scherg M
J Clin Neurophysiol · 2026 Jun · PMID 42235074 · Publisher ↗
Accurate interpretation of scalp electroencephalogram (EEG) signals relies on understanding the biophysical principles underlying their generation. Although traditional EEG analysis often focuses on identifying negative...
Accurate interpretation of scalp electroencephalogram (EEG) signals relies on understanding the biophysical principles underlying their generation. Although traditional EEG analysis often focuses on identifying negative phase reversals, this approach oversimplifies the complex nature of cortical current flow. Electroencephalogram signals are generated by extracellular currents resulting from postsynaptic potentials in pyramidal neurons, forming dipoles aligned along the apical dendrites. The orientation and location of these dipoles, whether radial, tangential, or oblique, depend on the spatial orientation of the active cortical surface. Orientation critically influences the scalp voltage topography. Therefore, the spatial distribution of both positive and negative poles on the scalp provides valuable insight into source localization. This review highlights the importance of including both polarities when interpreting EEG, particularly in distinguishing tangential and oblique from radial sources. It also emphasizes the role of electrode placement, montage selection, and digital filtering. Simultaneous MEG-EEG recordings further validate the physiologic significance of scalp positivities. Through practical examples and voltage maps, the authors advocate for a shift in clinical EEG interpretation, from relying solely on negativity and phase reversals to a more informed, topographic approach. Such an approach enhances diagnostic accuracy and aligns EEG interpretation with a more complete neurophysiologic understanding.
Consistency of Ictal Epileptogenic Foci in Children With Tuberous Sclerosis Complex and Its Clinical Predictors.
Stevering C, Otte W, Leijten F … +4 more , Bourez M, Wagner L, Braun K, Jansen FE
J Clin Neurophysiol · 2026 May · PMID 42159359 · Publisher ↗
PURPOSE: The course of epilepsy in patients with tuberous sclerosis complex (TSC) is highly variable. Consistency of the epileptogenic zone is considered important in presurgical evaluation. The authors aimed to (1) asse...
PURPOSE: The course of epilepsy in patients with tuberous sclerosis complex (TSC) is highly variable. Consistency of the epileptogenic zone is considered important in presurgical evaluation. The authors aimed to (1) assess consistency of ictal epileptogenic foci over time in patients with TSC, (2) evaluate concordance between interictal epileptiform abnormalities and ictal epileptogenic foci, and (3) identify determinants of ictal consistency. METHODS: This single-center retrospective, observational study included children with definite TSC and epilepsy with ≥2 ictal presurgical EEGs with an interval ≥1 year. In all EEGs, the regional localization of interictal and ictal epileptiform abnormalities was scored based on the EEG reports. All ictal epileptogenic foci were classified with an "ictal focus consistency score," according to one of the following subcategories: "single focus, consistent," "from unclear localization/diffuse or generalized to unifocal," "≥2 or more foci, each consistent," "≥2 foci of which at least one is consistent," "starting multifocal but at last EEG unifocal," and "multifocal changing otherwise." The primary end point was unifocal or multifocal consistency of ictal foci. The secondary end point was concordance between ictal epileptogenic foci and localization of interictal epileptiform abnormalities. The third end point involved an exploratory assessment of potential determinants of ictal consistency, including TSC variant, age at epilepsy onset, epileptic spasms, multiple seizure types, interictal multifocality, and tuber load. RESULTS: The authors included 45 patients with TSC with a median of 3 (interquartile range 2-4) ictal and 8 (interquartile range 5-10) interictal EEGs per patient. Median time between first and last ictal EEG was 28.4 months (19.0-60.3). Ictal foci were consistent over time in 11 patients (24.4%), of whom 9 had 1 consistent ictal focus. Nine other patients had a single consistent ictal focus on the first EEGs, but developed a second focus at the median age of 67.7 months. Of the 13 patients who later underwent surgery, 3 had a single focus, and only 2 of 13 had consistent ictal EEGs. The same three patients with a single focus over time were part of the seven postoperative seizure-free patients. All six nonseizure-free children had ictal multifocality. Interictal and ictal epileptogenic foci were discordant in 42 of 45 patients (93.3%). Exploratory analyses of potential determinants of ictal consistency suggested a negative association with interictal multifocality (risk ratio 0.32, 95% confidence interval 0.06-0.97, p = 0.04), which was not significant after adjustment for monitoring duration. CONCLUSIONS: Ictal epileptogenic foci are consistent in only 25% of the patients with TSC. Interictal epileptogenic foci are often discordant with ictal foci. This instability in the ictal epileptogenic focus might be explained by the presence of larger epileptogenic networks in TSC that undergo evolution over time. SIGNIFICANCE: The findings in this study could have important implications for presurgical evaluation in patients with TSC and might help to understand the cause of (late) surgical failure.
Predictive Value of Single-Fiber Electromyography for Ocular Myasthenia Gravis in a Low Prevalence Cohort.
Gomez Y, Puwanant A, Caress JB
J Clin Neurophysiol · 2026 May · PMID 42138399 · Publisher ↗
PURPOSE: Single-fiber electromyography (SFEMG) is a sensitive test to diagnose ocular myasthenia gravis (OMG) when the clinical suspicion is high but the predictive value of the test is also dependent on the prevalence o...
PURPOSE: Single-fiber electromyography (SFEMG) is a sensitive test to diagnose ocular myasthenia gravis (OMG) when the clinical suspicion is high but the predictive value of the test is also dependent on the prevalence of the condition in the referral population. In a low prevalence population, false positive results can be as common as true positive results. Most of the patients referred for SFEMG at our center do not have symptoms or signs that are strongly suggestive for OMG. METHODS: A retrospective chart review was performed of all patients referred to our laboratory for possible OMG for a 1-year period and analyzed the long-term accuracy of SFEMG in a cohort of 33 patients. RESULTS: Eleven of these (33%) were eventually diagnosed with a disease of neuromuscular transmission and SFEMG was abnormal in all of these (100% sensitivity). With the requirement that 3 jitter pairs be abnormal or that mean jitter was elevated, SFEMG was normal in the remaining 22 patients (100% specific). CONCLUSIONS: The results confirm that SFEMG is an excellent confirmatory test when clinical suspicion for OMG is high and also demonstrate that when strict criteria are applied, the test accurately excludes OMG in patients with ocular complaints that are not truly suggestive of OMG.
Association of Motor Unit Number and Size Estimation With Muscle Thickness and Strength in Healthy Young, Middle-Aged, and Older Adults.
Igawa K, Takeda R, Nishikawa T … +4 more , Karaki M, Kuniki M, Noto YI, Watanabe K
J Clin Neurophysiol · 2026 May · PMID 42117692 · Publisher ↗
PURPOSE: Although age-related declines in muscle mass and strength are believed to result from changes in motor unit number and size, the association of motor unit number and size with muscle mass and strength in healthy...
PURPOSE: Although age-related declines in muscle mass and strength are believed to result from changes in motor unit number and size, the association of motor unit number and size with muscle mass and strength in healthy individuals remains unclear. We aim to examine the association of motor unit number estimation (MUNE) and motor unit size estimation (MUSE) of abductor pollicis brevis (APB) with muscle thickness of APB and maximal pinch-grip strength among young, middle-aged, and older adults. METHODS: Forty-eight young adults (20-39 years; young), 89 middle-aged adults (40-59 years; middle-aged), and 47 older adults (60 years and older; older) participated in this study. MUNE and the mean single motor unit potential as MUSE were calculated using the MScanFit2. Muscle thickness of the APB was measured from ultrasound images. Maximal pinch-grip strength was assessed during maximal voluntary isometric contraction of lateral pinch. RESULTS: MUNE and MUSE were not correlated with muscle thickness in any of the groups. In addition, MUNE was not correlated with maximal pinch-grip strength in either the young or middle-aged group. A significant positive correlation between MUNE and maximal pinch-grip strength was observed in the older group. MUSE was not significantly correlated with maximal pinch-grip strength in any group. CONCLUSIONS: MUNE, not MUSE, is associated with maximal pinch-grip strength in older adults, but not in young or middle-aged adults. These findings suggest that MUNE may explain interindividual differences in neuromuscular function among healthy older adults. MUNE could be a useful biomarker for neuromuscular function in older individuals.
Sonographic Normal Values for Ulnar Nerve Cross-Sectional Area.
Luetmer MT, Meiling JB, Sorenson EJ … +2 more , Laughlin RS, Boon AJ
J Clin Neurophysiol · 2026 May · PMID 42117691 · Publisher ↗
PURPOSE: Neuromuscular ultrasound, including cross-sectional area measurements, adds diagnostic value to the clinical and electrodiagnosis evaluation of ulnar neuropathy at the elbow. Previously published reference value...
PURPOSE: Neuromuscular ultrasound, including cross-sectional area measurements, adds diagnostic value to the clinical and electrodiagnosis evaluation of ulnar neuropathy at the elbow. Previously published reference values for ulnar nerve size vary widely. Our objective was to establish age-specific reference values for ulnar nerve cross-sectional area at multiple sites in asymptomatic adults for our laboratory. METHODS: Healthy adult subjects without neuromuscular symptoms or disease were recruited from our tertiary referral electromyogram laboratory and staff. Ulnar nerve cross-sectional area measurements were made in short axis at the wrist, forearm, cubital tunnel, retrocondylar groove, 2 cm proximal to the medial epicondyle, and mid-upper arm with the elbow flexed to 90°. Dynamic neuromuscular ultrasound evaluated for subluxation and dislocation at the medial epicondyle. Results were stratified by age group (younger than 40, 40-60, and older than 60 years) with at least 20 subjects per sex per group, as well as by sex, body mass index, and handedness. The upper limit of normal was established as two standard deviations above the mean. RESULTS: One hundred forty-two subjects (ages 18-84, mean 47.7 years) were included. Cross-sectional area significantly increased with age at all sites except the wrist. Cross-sectional area cut-offs at the retrocondylar groove were 10.0, 10.9, and 11.4 mm 2 , respectively, by age group. Ratios comparing retrocondylar groove and cubital tunnel to arm and forearm were calculated. Thirty-two percent had subluxation or dislocation in at least one limb. CONCLUSIONS: Age-specific cross-sectional area cut-offs and ratios may facilitate a more nuanced interpretation and diagnostic value when used in conjunction with clinical and electrodiagnosis evaluation of ulnar neuropathy at the elbow.
Technical Optimization and Clinical Utility of Intraoperative Visual Evoked Potentials During Transsphenoidal Surgery for Pituitary Adenomas.
Choi J, Kim KE, Song MJ … +2 more , Lee JH, Yoon BH
J Clin Neurophysiol · 2026 May · PMID 42113597 · Publisher ↗
PURPOSE: To evaluate clinical and technical factors associated with successful intraoperative visual evoked potential (VEP) acquisition during transsphenoidal surgery (TSS) for pituitary adenomas, and to assess the progn...
PURPOSE: To evaluate clinical and technical factors associated with successful intraoperative visual evoked potential (VEP) acquisition during transsphenoidal surgery (TSS) for pituitary adenomas, and to assess the prognostic value of intraoperative VEP changes on postoperative visual outcomes. METHODS: A total of 163 patients who underwent primary TSS with intraoperative VEP monitoring between January 2016 and December 2024 were analyzed. Baseline signal acquisition and visual outcomes at 1 month postsurgery were assessed in relation to tumor characteristics, preoperative visual function, stimulation modality (goggle-mounted vs. high-luminance light-emitting diode [LED]), and use of concurrent electroretinography (ERG). Multivariable logistic regression identified independent predictors of successful VEP acquisition. RESULTS: Visual evoked potentials were successfully obtained in 78.8% of eyes. Higher acquisition rates were observed in patients with tumors <10 mm, intrasellar location, and preserved visual function (all P < 0.05). The high-luminance LED system with ERG significantly improved signal acquisition (89.0 vs. 64.3%, P < 0.001). Among patients monitored with this optimized approach, irreversible intraoperative VEP loss strongly predicted postoperative visual deterioration (70.8 vs. 8.2%, P < 0.001). No such association was observed with the goggle-based system. CONCLUSIONS: Technically optimized VEP monitoring using high-luminance stimulation and ERG validation improves signal reliability and prognostic value for visual outcomes in pituitary surgery. Broader adoption may be supported by standardized protocols and careful patient selection.
Collodion Versus Tensive-Quality and Cost Comparison in 48-hour Ambulatory EEG Studies.
Ashaye T, Cole S, Pierce D … +3 more , Warzecha M, Sarol JN, Ahmed F
J Clin Neurophysiol · 2026 May · PMID 42101150 · Publisher ↗
PURPOSE: To determine whether there is a difference in electrode impedances in 48-hour in-home ambulatory EEGs (AEEG) when using collodion versus Tensive for electrode application. In addition, to compare the costs of us...
PURPOSE: To determine whether there is a difference in electrode impedances in 48-hour in-home ambulatory EEGs (AEEG) when using collodion versus Tensive for electrode application. In addition, to compare the costs of using the two adhesive agents. METHODS: This retrospective review analyzed 252 intermittently monitored 48-hour ambulatory EEG studies conducted in adult patients. In total, 126 studies were conducted using collodion and 126 using Tensive for electrode application. Each group was composed of an equal number of male and female. Electrode impedances were checked and documented at least every 4 hours, more frequently if artifact was noticed by the registered EEG technologist (R.EEG T.) during intermittent monitoring. The number of electrodes in which impedance exceeded 10 kOhms anytime during the 48-hour study was assessed. In addition, the per-patient cost of collodion and its required ancillary supplies was compared with that of Tensive. RESULTS: The incidence of impedances greater than 10 kOhms in 48-hour ambulatory EEGs was similar for the collodion and Tensive groups. It was 42.1% for collodion and 45.2% for Tensive. The difference between the two adhesives was not statistically significant (P = 0.6114). There was a 73% cost reduction per patient when using Tensive compared with collodion. CONCLUSIONS: There is no significant difference in the maintenance of proper electrode impedance in 48-hour ambulatory EEGs when using collodion or Tensive for electrode application. There is a 73% cost reduction per patient when using Tensive.
Electrical Source Imaging in Stereoelectroencephalography: A Proof-of-Concept Study.
Bosisio L, Cataldi M, Tortora D … +6 more , Consales A, Nobile G, Mikulan E, Marazzotta V, Nobili L, Francione S
J Clin Neurophysiol · 2026 May · PMID 42085513 · Publisher ↗
PURPOSE: Electrical source imaging (ESI) estimates the intracerebral generators of EEG signals. Although traditionally applied to scalp EEG sensors, recent studies suggested its potential applicability to intracerebral r...
PURPOSE: Electrical source imaging (ESI) estimates the intracerebral generators of EEG signals. Although traditionally applied to scalp EEG sensors, recent studies suggested its potential applicability to intracerebral recordings. We systematically evaluated the localization accuracy of ESI applied to SEEG data rather than scalp EEG. METHODS: We compared three different inverse solution methods (standardized low-resolution electromagnetic tomography [sLORETA], minimum norm estimate, and dynamic statistical parametric mapping) in localizing the stimulation artifact in 12 subjects undergoing SEEG. Localization accuracy was defined as the Euclidean distance between the stimulation site and the peak of the estimated source. RESULTS: Standardized low-resolution electromagnetic tomography showed the highest accuracy. For single stimuli, the mean localization error was 11.65 mm, improving to 9.28 mm when averaging 10 stimuli. Subcentimeter accuracy was achieved in 77.5% of averaged trials. Although localization based on the maximum amplitude artifact increased linearly with the distance from the nearest SEEG contact, sLORETA maintained higher accuracy, typically within ∼1 cm. The weak association between sLORETA error and sensor distance disappeared when excluding stimulations at the outermost boundaries of the explored region. CONCLUSIONS: These results support the application of ESI to SEEG data for accurate source localization. Among tested methods, sLORETA was the most effective and may improve spatial interpretability in challenging epilepsy cases, including those with suboptimal spatial sampling.
Understanding of Rapid Ictal Blinking: Definition Criteria, Prevalence, and Localizing Value.
Salehizadeh S, Thyagaraj S, Fotedar N … +2 more , Garcia-Losarcos N, Lüders H
J Clin Neurophysiol · 2026 Apr · PMID 41972753 · Publisher ↗
PURPOSE: Ictal blinking is an undefined phenomenon of involuntary bilateral blinks during a seizure, at a higher frequency than baseline blinking that is not associated with other facial motor manifestations. In most rep...
PURPOSE: Ictal blinking is an undefined phenomenon of involuntary bilateral blinks during a seizure, at a higher frequency than baseline blinking that is not associated with other facial motor manifestations. In most reports, the epileptogenic zone has been identified in the occipital regions. The purpose of this study is to characterize ictal blinking and assess its potential localizing value. METHOD: EEG and EOG data from 45 patients with seizures from temporal, occipito-parietal, and fronto-central regions (15 per group) were analyzed. Blinks were quantified in 15-second epochs during ictal and baseline phases. Baseline duration matched the ictal phase or extended to 150 seconds. RIB is defined as the blinking rate at least 50% greater than the average baseline blinking during any ictal window. The ictal blinking rate ratio (BRR) was also calculated for each group, defined as the ratio of maximum ictal blinks to average baseline blinks. Ictal blink suppression (BS) was defined as no blinks in the first 30 seconds of a seizure. RESULTS: The average blinking frequency during the baseline period was four blinks every 15-second page. The average ictal blinks for patients who met the criteria for RIB were seven per 15-second page. RIB occurs most frequently in temporal epilepsy (73%) and less commonly in frontal epilepsy (47%). Ictal BRR is highest (5.6) in occipital epilepsy. Ictal BS occurred in 22% of cohort. CONCLUSIONS: RIB is a frequent ictal phenomenon without significant localizing value. Ictal BRR was significantly higher for patients with occipital seizures. Based on the findings, a practical definition for RIB was proposed: seven or more blinks in any 15-second epoch during seizure.
Generalized Periodic Discharges: Nonconvulsive Status Epilepticus or Diffuse Encephalopathy-A Case Comparison.
Hirunpattarasilp C, Edmondson J, Wood D … +2 more , Fernandez-BacaVaca G, Fotedar N
J Clin Neurophysiol · 2026 Apr · PMID 41925371 · Publisher ↗
Nonconvulsive status epilepticus (NCSE) refers to persistent epileptiform discharges on EEG meeting the Salzburg criteria. Nonconvulsive status epilepticus with coma mostly occurs in critically ill patients without prece...
Nonconvulsive status epilepticus (NCSE) refers to persistent epileptiform discharges on EEG meeting the Salzburg criteria. Nonconvulsive status epilepticus with coma mostly occurs in critically ill patients without preceding convulsions and without a history of chronic epilepsy, where the EEG typically shows generalized periodic discharges (GPDs). Nonconvulsive status epilepticus without coma is typically described in patients with chronic epilepsy and is associated with a different alteration of consciousness where patients are awake with eyes open, retained posture, however unresponsive with amnesia (known as dialepsis). The GPDs in NCSE with coma could represent an epiphenomenon and the coma might not be a direct result of the GPDs. In contrast, the dialeptic state in NCSE without coma is a true manifestation of the epileptiform discharges, hence warranting treatment with antiseizure medications. In this report, a case of NCSE with coma is described caused by ceftriaxone-induced neurotoxicity and its electroclinical characteristics are compared with a case of NCSE without coma in a patient with chronic focal epilepsy.
Safety and Feasibility of Transcranial Motor-Evoked Potentials During Intraoperative Neurophysiologic Monitoring in Patients With Deep Brain Stimulators.
Meyers N, Keroles M, Cho SC … +7 more , Gummi R, Le S, Lee L, Nguyen V, Tippur A, López JR, Chang F
J Clin Neurophysiol · 2026 Apr · PMID 41925348 · Publisher ↗
PURPOSE: Transcranial motor-evoked potentials (TcMEPs) are routinely used for intraoperative neurophysiologic monitoring to assess corticospinal tract integrity. However, data regarding the use of TcMEPs in patients with...
PURPOSE: Transcranial motor-evoked potentials (TcMEPs) are routinely used for intraoperative neurophysiologic monitoring to assess corticospinal tract integrity. However, data regarding the use of TcMEPs in patients with implanted deep brain stimulator (DBS) devices remain limited. This study aims to evaluate the safety and feasibility of TcMEP monitoring in patients with implanted DBS systems undergoing a variety of surgical procedures. METHODS: A retrospective review was conducted using clinical and neurophysiologic data from patients with DBS devices who underwent surgery with TcMEP monitoring at a single institution between 2014 and 2024. Patient demographics, surgical and device information, TcMEP stimulation parameters, and intraoperative neurophysiologic monitoring documentation, as well as intraoperative and postoperative clinical notes were reviewed. RESULTS: Sixteen patients were identified who underwent 19 surgical procedures with TcMEP monitoring. Reliable TcMEP signals were successfully obtained in all patients across a variety of surgical procedures, DBS targets, and stimulation parameters (80-520 V, 147-1,388 mA). No TcMEP-related intraoperative or postoperative complications were identified, and DBS device functionality remained preserved. However, active DBS stimulation during surgery generated electrical artifacts that interfered with other intraoperative neurophysiologic monitoring modalities, including somatosensory evoked potentials and EEG (electroencephalogram). CONCLUSIONS: Transcranial motor-evoked potentials monitoring is safe and feasible in patients with implanted DBS devices undergoing a variety of surgical procedures. Standard TcMEP stimulation parameters can be implemented without significant modification. To minimize interference with multimodal intraoperative neurophysiologic monitoring, DBS devices should be turned off during monitoring. Further studies are needed to establish standardized guidelines for TcMEP monitoring in patients with DBS and other intracranial neurostimulation devices.
Estimating Reference Limits for Motor Conduction Block Using Latency Adjustment and a Modified MeRef Model.
Engedal TS, Qerama E, Benediktsson JÁ … +3 more , Kjeldsen OR, Johnsen B, Hokland S
J Clin Neurophysiol · 2026 Mar · PMID 41891699 · Publisher ↗
INTRODUCTION: Current thresholds for motor conduction block on nerve conduction studies are primarily based on expert opinion and fail to consider individual patient- or nerve-specific characteristics. In this article, w...
INTRODUCTION: Current thresholds for motor conduction block on nerve conduction studies are primarily based on expert opinion and fail to consider individual patient- or nerve-specific characteristics. In this article, we aimed to improve diagnostic accuracy for identifying partial motor conduction block and determine the influence of latency difference (LD) between proximal and distal stimulation on amplitude decay in unaffected nerves. METHODS: We developed the multivariate extrapolated truncated fit model to establish reference limits for amplitude decay depending on LD using existing nerve conduction studies data and compared these with existing literature values and with published thresholds for conduction block. RESULTS: A total of 67,266 investigations of the forearm or lower leg segments of the median, ulnar, peroneal, and tibial nerves were included. The mean multivariate extrapolated truncated fit upper limits (model +2SD) for amplitude decay in nerves with normal distal amplitude/decreased distal amplitude were: Median 14.3%/24.1%, Ulnar 17.5%/34.4%, Peroneal 27.7%/41%, and Tibial 46%/57.1%. For the four nerves, we observed 1.7% to 5.1% increases in amplitude decay per ms increase in LD. Contrary to the multivariate extrapolated truncated fit reference limits, existing thresholds for conduction block produced inconsistent positive rates between nerves with a high risk of false positive and negative results. CONCLUSIONS: Amplitude decay on nerve conduction studies was dependent on LD, and the multivariate extrapolated truncated fit model showed promise as a tool to create reference limits from large data sets. Reference limits adjusted for LD could improve diagnosis of inflammatory polyneuropathies and other conditions with conduction block.
Magnetoencephalography as a Novel Tool for Prenatal Diagnosis of Fetal Seizures.
Whitcombe DD, Escalona-Vargas D, Eswaran H … +4 more , Moody H, Mercado L, Dajani NK, Samanta D
J Clin Neurophysiol · 2026 Jul · PMID 41885425 · Publisher ↗
Fetal seizures represent one of the rarest phenomena in prenatal medicine, with fewer than 50 documented cases. Diagnosis has traditionally relied on maternal reports and ultrasound visualization of abnormal movements, l...
Fetal seizures represent one of the rarest phenomena in prenatal medicine, with fewer than 50 documented cases. Diagnosis has traditionally relied on maternal reports and ultrasound visualization of abnormal movements, lacking the neurophysiologic confirmation available in neonatal care. This case report presents the first neurophysiologic assessment of fetal seizures using fetal magnetoencephalography (fMEG), demonstrating a novel diagnostic approach for prenatal neurologic evaluation. A 22-year-old primigravida with controlled epilepsy presented with a fetus showing severe growth restriction and multiple anomalies at 23 weeks gestation. At 32 weeks, repetitive rhythmic jerking movements suggested in utero seizures and were confirmed with real-time ultrasound. fMEG was performed using the SQUID Array for Reproductive Assessment (SARA) system, revealing immature patterns indicative of encephalopathy with alternating periods of severe bilateral suppression and low-amplitude activity. Bursts lasting up to 6 seconds coincided with erratic body movements confirmed by actogram. The infant was delivered at 37 weeks weighing 1,200 g and continued to exhibit myoclonic and clonic seizures postnatally. Postmortem whole exome sequencing identified biallelic pathogenic variants in PSAT1 , confirming Neu-Laxova syndrome. The infant died on the fifth day of life after transition to comfort care. This case demonstrates the feasibility of direct neurophysiologic assessment of fetal brain activity using fMEG, providing objective confirmation of fetal seizures for the first time. The technology offers potential for distinguishing true fetal seizures from other conditions that mimic seizure-like movements, enabling more accurate prenatal counseling and informed decision making. This represents a significant advancement in prenatal neurologic assessment, with implications for early diagnosis and targeted interventions.
Low Frequency Stimulation and Seizure Induction in Pediatric and Young Adult Patients With Drug Resistant Epilepsy Undergoing Stereoelectroencephalography.
Armstrong C, Tomlinson SB, Davis P … +5 more , Ojemann W, Kilaru Kessler S, Kennedy BC, Conrad EC, Marsh ED
J Clin Neurophysiol · 2026 Mar · PMID 41823409 · Publisher ↗
PURPOSE: Describe the tolerability and outcome of direct brain stimulation for seizure induction in children and young adults undergoing intracranial electroencephalography. METHODS: Patients received low frequency stimu...
PURPOSE: Describe the tolerability and outcome of direct brain stimulation for seizure induction in children and young adults undergoing intracranial electroencephalography. METHODS: Patients received low frequency stimulation (LFS) consisting of 30 seconds of 1 Hz bipolar, biphasic brain stimulation. A subset also received high frequency stimulation (HFS) for clinical purposes. Clinical data regarding epilepsy characteristics, stimulation, and outcomes were collected. RESULTS: Fifty-four patients (aged 1.8 to 23.4 years) with pediatric onset epilepsy were enrolled at Children's Hospital of Philadelphia and the Hospital of the University of Pennsylvania. Side effects during LFS included focal sensation (22%) and motor responses (41%). Non-seizure electrographic abnormalities were noted during stimulation in 87% of patients. During LFS, typical clinical seizures were seen in 24% of patients. During HFS (50 Hz), 58% of 36 patients had seizures (71% typical semiology). In 30% of patients, stimulated typical clinical seizures identified a contact not previously identified as part of the seizure onset zone. Of 43 patients who went on to have resection, ablation, or neuromodulation, 39 patients had ≥12 months of follow-up. Although 84% of 19 patients with stimulated typical clinical seizures had a good outcome, 60% of 20 patients with atypical or no clinical seizures during stimulation had good outcomes (P = 0.09). CONCLUSIONS: LFS is well tolerated in pediatric and young adult DRE patients and in one fourth of cases identifies potential additional nodes of the seizure network. These data, consistent with adult studies, affirm that LFS has a role complementing HFS in evaluating pediatric DRE patients undergoing stereoelectroencephalography.
High-Resolution Ultrasonography for Detecting Peripheral Neuropathy in Leprosy: A Systematic Review and Meta-Analysis.
Metwally SA, Al Haj Ali S, Tantawy M … +10 more , Ataky N, Eltaib KM, Elatrosh ME, Al-Ghorbany HA, Mohamed Magzoub AA, Ibraheem Mdalal BA, Helmy Hussein AM, Mohamed KA, Bedewi MA, Awad EM
J Clin Neurophysiol · 2026 Mar · PMID 41773898 · Publisher ↗
BACKGROUND: Leprosy is a chronic granulomatous disease that commonly affects the peripheral nervous system, often leading to significant disability. High-resolution ultrasonography has emerged as a promising tool for the...
BACKGROUND: Leprosy is a chronic granulomatous disease that commonly affects the peripheral nervous system, often leading to significant disability. High-resolution ultrasonography has emerged as a promising tool for the noninvasive assessment of nerve involvement in leprosy. OBJECTIVE: To figure out the diagnostic value of HRUS in assessing peripheral nerve involvement in leprosy, with a focus on measuring the cross-sectional area (CSA) of major nerves. METHODS: A systematic search of PubMed, Scopus, Web of Science, and Embase was conducted up to 2024. Seventeen studies were included, and quality assessment was performed using NIH and NOS tools. Meta-analyses compared CSA of the ulnar, median, posterior tibial, and common fibular nerves between patients with leprosy and healthy controls. Heterogeneity was evaluated using the I2 statistic and sensitivity analyses were performed. RESULTS: Patients with leprosy showed significantly increased CSA in all examined nerves compared with controls. Single-arm analysis of CSA in patients with leprosy showed consistent nerve enlargement, particularly in the ulnar nerve. CONCLUSIONS: Our review shows the usefulness of HRUS as a sensitive, noninvasive imaging modality for evaluating peripheral nerve involvement in leprosy.
Rapid EEG Monitoring in Clinical Practice.
Gururangan K, Philibert-Rosas S, Subramaniam T
J Clin Neurophysiol · 2026 Mar · PMID 41773897 · Publisher ↗
Rapid electroencephalography (EEG) devices have emerged in response to the growing awareness of seizures and highly epileptiform patterns in critically ill patients and limitations associated with conventional EEG infras...
Rapid electroencephalography (EEG) devices have emerged in response to the growing awareness of seizures and highly epileptiform patterns in critically ill patients and limitations associated with conventional EEG infrastructure. In this review, we describe rapid EEG utilization patterns, clinical workflows, implementation challenges, and financial considerations using a narrative review supplemented by a multi-institutional survey of 20 centers affiliated within the Critical Care EEG Monitoring Research Consortium. We identified that rapid EEG was perceived to expedite diagnosis and treatment decisions and enhance clinical triage, and most respondents perceived the cost of rapid EEG sessions to be low. However, commonly cited limitations included lower spatial resolution and unsuitability for replacing conventional EEG for prolonged monitoring. Prior cohort studies and clinical trials of rapid EEG devices display site-by-site variability in practical workflows regarding specificity of clinical indications for monitoring and designated personnel for device setup and EEG review, however, rapid EEG was reported to consistently augment EEG monitoring capabilities even at centers with access to conventional EEG. Because rapid EEG devices are increasingly adopted, and paired with artificial intelligence tools, it will be vital for institutions to develop protocols and guidelines with multidisciplinary input to steer their responsible, effective, and sustainable use.
Rapid EEG in Specific Clinical Situations.
Patedakis Litvinov B, Benbadis SR, Hirsch LJ
J Clin Neurophysiol · 2026 Mar · PMID 41773896 · Publisher ↗
Electroencephalography (EEG) is a critical tool for diagnosing epilepsy and recording seizures. Rapid EEG (rEEG) technology addresses challenges associated with traditional EEG by offering portable, easy-to-use systems t...
Electroencephalography (EEG) is a critical tool for diagnosing epilepsy and recording seizures. Rapid EEG (rEEG) technology addresses challenges associated with traditional EEG by offering portable, easy-to-use systems that nonspecialists can deploy quickly. This review focuses on the clinical utility of rEEG, highlighting studies that explore its effectiveness in various settings, compare its performance to conventional EEG, and discuss its impact on patient outcomes, health care costs, and resource utilization. Among rEEG systems, Ceribell is the most studied, with clinical trials supporting its utility across multiple settings. Although rEEG offers significant advantages in rapid deployment and ease of use, limitations include reduced EEG channels and reliance on automated detection tools, emphasizing the need for expert oversight. Case studies illustrate both the utility and limitations of rEEG. Integration of rEEG into routine clinical practice promises improved patient outcomes, reduced healthcare costs, and more efficient resource utilization, particularly in emergency departments, critical care settings, and underserved areas.
Rapid-EEG Software Architecture's Clinical Impact: Advantages and Limitations.
Fisch U, Lee JW
J Clin Neurophysiol · 2026 Mar · PMID 41773895 · Publisher ↗
Rapid electroencephalography (EEG) devices are portable, easy-to-use systems that provide automated EEG interpretation to guide clinical decisions at the bedside. The scope of this review outlines the principles of autom...
Rapid electroencephalography (EEG) devices are portable, easy-to-use systems that provide automated EEG interpretation to guide clinical decisions at the bedside. The scope of this review outlines the principles of automatic EEG analysis methods and the impact of recent developments in artificial intelligence and machine learning on these techniques in the context of seizure detection. The first generation of rapid EEG devices, primarily developed for anesthesia management, were tested for seizure detection; although raw EEG traces and power density arrays from these devices were helpful in seizure monitoring, their proprietary algorithms were not reliable for this purpose. The next generation of rapid EEG devices were principally aimed at seizure detection. In several large retrospective research studies, deep learning algorithms have demonstrated equal or superior proficiency as compared with human experts. Recent guidelines from the US Food and Drug Administration describe several guiding principles for this class of algorithms to be incorporated into medical devices. However, the "black box" nature of proprietary algorithms remains a concern because it hinders understanding of the device's limitations and potential pitfalls. We advocate for transparent reporting of essential software features to foster a constructive interaction between clinical users and rapid EEG device developers. This transparency is crucial for the continuous improvement of these devices, their acceptance among users, and ultimately, better patient care.
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