Journal of Clinical Neurophysiology最新文献

Purpose: High-frequency ultrasound (HFUS) of muscle and nerve has the potential to be a reliable, responsive, and informative biomarker of disease progression for individuals with amyotrophic lateral sclerosis (ALS). High-frequency ultrasound is not able to visualize median nerve fascicles to the same extent as ultra-high-frequency ultrasound (UHFUS). Evaluating the number and size of fascicles within a nerve may facilitate a better understanding of nerve diseases. This exploratory study aims to image median nerve fascicles at the wrist in individuals with ALS using UHFUS and compare these findings with those from previously observed controls.

Methods: Fifteen individuals with ALS underwent sonographic examination of the median nerves on each upper limb using UHFUS with a 48-MHz linear array transducer. Fascicle count and density in each examined nerve were determined by a single rater. Demographic and sonographic data from 20 previously studied controls were compared.

Results: In individuals with ALS, the average fascicle number was 22.4 (SD 5.2) and average fascicle density 1.7 (SD 0.5). There was no significant difference in fascicle counts between individuals with ALS and controls.

Conclusions: Fascicular quantification using UHFUS is possible in individuals with ALS. Given the lack of appreciable difference between fascicle counts in individuals with ALS and controls, UHFUS of the median nerve at the wrist may not be a responsive biomarker for ALS disease progression.

Summary: The lack of reliable seizure detection remains a significant challenge for epilepsy care. A clinical deep brain stimulation (DBS) system provides constrained ambulatory brain recordings; however, limited data exist on the use of DBS recordings for seizure detection and lateralization. We present the case of an 18-year-old patient with drug-resistant focal epilepsy, who had seizure detection and lateralization by DBS recordings. Prior stereotactic-EEG, including a thalamus lead, identified independent left orbitofrontal and mesial temporal onset seizures. Notably, low-frequency thalamic ictal power was significantly elevated relative to baseline awake and sleep states. The patient was subsequently implanted with an anterior nucleus of the thalamus DBS system. Postimplantation, low-frequency power-in-band (5.3-10.3 Hz) recordings were initiated. Nursing staff identified four typical clinical seizures during the inpatient DBS recording period. Thalamic DBS trends contained relative peaks that were coincident with each nurse-reported seizure. Peri-ictal power was uniformly maximal ipsilateral to the seizure network. This case demonstrates the feasibility of seizure detection and lateralization by a thalamic DBS system for some individuals, and suggests DBS sensing parameter selection may be guided by thalamic stereotactic EEG. Further research is necessary to assess the generalizability of DBS seizure detection across individuals and diverse seizure networks.

Purpose: To investigate the utility of a 15-minute online module to improve the self-confidence and knowledge of neurology trainees when screening an EEG.

Methods: We developed a fast, convenient, and accessible 15-minute online module to teach basic concepts of EEG screening using a five-step approach. To assess the efficacy of the module among neurology trainees, three surveys were developed. The EEG module and surveys were distributed to neurology trainees at multiple institutions in the United States. Associations between continuous variables were evaluated using t-test and ANOVA test.

Results: A total of 199 residents from 7 different adult neurology residency programs participated in the study. We obtained a response rate of 38% (76/199) for EEG survey 1 and 25% (49/199) for the demographic survey, among junior and senior residents; 22 senior residents completed EEG survey 2. The online EEG module improved confidence when interpreting an EEG among junior residents (1.67 vs. 2.56, p < 0.0001). Senior residents improved their EEG survey score after completing the online module (53.9 vs. 68.6%, p < 0.001). Most of the trainees would recommend the online module to other trainees (93.9%) and would consider including it in an introductory course (93.9%).

Conclusions: A brief and accessible online EEG module was easily implemented as an early introduction to EEG screening for junior neurology trainees and to improve EEG screening skills for senior trainees. These findings clarify specific areas where EEG learning may be optimized and reinforce the importance of implementing innovative curricula that are accessible and efficient for all neurology trainees.

Purpose: Sleep deprivation (SD) reduces time to task failure during endurance exercises. The aim of our work was to study the effect of acute SD on the endurance of a skeletal hand muscle and to investigate cortical motor drive to muscle and perception of effort.

Methods: Origin of the early exhaustion after SD might be insufficient cortical motor drive to muscle or motor inhibition because of excessive perception of effort. The supplementary motor area, the medial part of the premotor cortex, links the motor and sensory cortexes, prepares for voluntary movements, and may play a central role in the pathophysiology of impaired muscle endurance after SD. Supplementary motor area can be noninvasively assessed by electromyogram measuring amplitude of premotor potentials before hand movements. We investigated the effect of SD on muscle endurance in healthy volunteers performing moderate hand exercise by monitoring supplementary motor area activation and muscle afferents. Two sessions were performed, in random order, one after a normal sleep night and the other after a sleepless night.

Results: Twenty healthy young men were included in this study. Sleep deprivation reduced time to task failure by 11%. Supplementary motor area activation was altered throughout the task and effort perception was increased.

Conclusions: Our results suggest that SD reduces skeletal muscle endurance by increasing the effects of muscle afferents on the supplementary motor area. Sleep alterations frequently reported in chronic diseases might reduce patients' capacity to achieve the low-intensity motor exercises required in everyday life. Our results should lead to the search for sleep disorders in patients with chronic pathology.

Introduction: To assess the alpha-delta ratio (ADR) as a biomarker for cerebral injury and stroke in pediatric extracorporeal membrane oxygenation (ECMO).

Methods: Retrospective study of children aged >44 weeks gestation to 21 years monitored with continuous electroencephalography during ECMO. The interhemispheric ADR difference between the left and right hemisphere was calculated per hour. A t -test was performed comparing the mean interhemispheric difference between controls and patients with cerebral injury at set intervals (i.e., 1, 3, 6, 9, 12, and 24 hours) from the start of continuous electroencephalography. Injury was established if confirmed by imaging on the same day as ECMO cannulation and acquired if confirmed the day after ECMO or later. Analysis of variance was performed to compare the mean interhemispheric difference in the ADR among control patients to those with early-acquired and late-acquired injury at 24 hours.

Results: We included 49 patients with a median age of 3.4 years (interquartile range [1-10.4]), 47% (23/49) were male, and 73% (36/49) had cardiac arrest. Cerebrovascular injury was detected in 45% (22/49), with focal stroke in 82% (18/22). A significant difference was seen between control patients compared with cerebrovascular injury after 6 hours of continuous electroencephalography (0.016 vs. 0.042) (mean interhemispheric ADR difference) ( P = 0.03). Analysis of variance of control patients to early- and late-acquired injury at 24 hours showed a significant difference ( P = 0.03).

Conclusions: The ADR is a reliable metric to detect in-ECMO cerebral injury and stroke. Further study is needed to automate and assess this metric for real-time detection of stroke in ECMO.

Purpose: Electrical stimulation of trigeminal nerve branches elicits early and late reflex responses in the cervical muscles, known as the trigeminocervical reflex (TCR). This study aimed to evaluate the neurophysiological aspects, stimulation patterns, and topographic distribution of short-latency TCR components in humans in the absence of voluntary muscle activation.

Methods: This prospective observational study included 30 participants. Trigeminocervical reflex responses were simultaneously recorded from the bilateral sternocleidomastoid, trapezius, and splenius capitis muscles (without voluntary muscle activation), after electrical stimulation of the supraorbital and infraorbital nerves. Two different stimulation protocols were evaluated: a 3 Hz stimulation protocol (using averaging) and a single-pulse stimulation protocol.

Results: Using a 3 Hz stimulation protocol, short-latency TCR responses were recorded in the sternocleidomastoid, trapezius, and splenius capitis muscles, ipsilateral and/or contralateral, but with variable recordability depending on the recording site. The most reliable response was obtained in ipsilateral sternocleidomastoid muscle. To the best of our knowledge, this is the first study to demonstrate the elicitation of short-latency TCR components in the sternocleidomastoid muscle in the absence of voluntary muscle activation in humans without craniocervical junction disorders or lower brainstem abnormalities.

Conclusions: The choice of an appropriate stimulation protocol is particularly relevant for recording short-latency TCR components, considering that the visualization of early or late responses seems to be facilitated by different stimulation methodologies.

Purpose: Functional connectivity hubs were previously identified at the source level in low-risk full-term newborns by high-density electroencephalography (HD-EEG). However, the directionality of information flow among hubs remains unclear. The aim of this study was to study the directionality of information flow among source level hubs in low-risk full-term newborns using HD-EEG.

Methods: A retrospective analysis of HD-EEG collected from a prospective study. Subjects included 112 low-risk full-term (37-41 weeks' gestation) newborns born in a large delivery center and studied within 72 hours of life by HD-EEG. The directionality of information flow between hubs at the source level was quantified using the partial directed coherence in the delta frequency band. Descriptive statistics were used to identify the maximum and minimum information flow. Differences in information flow between cerebral hemispheres were assessed using Student t-test.

Results: There was higher information flow from the left hemisphere to the right hemisphere hubs (p < 0.05, t-statistic = 2). The brainstem had the highest information inflow and lowest outflow among all the hubs. The left putamen received the lowest information, and the right pallidum had the highest information outflow to other hubs.

Conclusions: In low-risk full-term newborns, there is a significant information flow asymmetry already present, with left hemisphere dominance at birth. The relationship between these findings and the more prevalent left hemisphere dominance observed in full-term newborns, particularly in relation to language, warrants further study.

Purpose: The purpose of this study was to determine the effect of sevoflurane anesthesia on spikes, high-frequency oscillations (HFOs), and phase-amplitude coupling using a modulation index in MRI-normal hippocampus, with the aim of evaluating the utility of intraoperative electrocorticography in identifying the epileptogenic hippocampus during sevoflurane administration.

Methods: Eleven patients with intractable temporal lobe epilepsy with a normal hippocampus on MRI underwent extra-operative electrocorticography evaluation. Patients were assigned to the Ictal (+) or Ictal (-) group depending on whether the parahippocampal gyrus was included in the seizure onset zone. Intraoperative electrocorticography was performed under 0.5 and 1.5 minimum alveolar concentration of sevoflurane. The rates of spikes, ripples, fast ripples (FRs), ripples on spikes, FRs on spikes, and MI HFO(3-4 Hz) were evaluated.

Results: During the intraoperative electrocorticography procedure, sevoflurane administration was found to significantly increase the rate of spikes, ripples on spikes, fast ripples on spikes, and MI HFO(3-4 Hz) in the Ictal (+) group ( P < 0.01). By contrast, the Ictal (-) group exhibited a paradoxical increase in the rate of ripples and fast ripple ( P < 0.05).

Conclusions: Our findings indicate that the administration of sevoflurane during intraoperative electrocorticography in patients with MRI-normal hippocampus can lead to a dose-dependent enhancement of epileptic biomarkers (spikes, ripples on spikes, fast ripples on spikes, and MI (HFO 3-4) ) in the epileptogenic hippocampus, while paradoxically increasing the rate of ripples and fast ripple in the nonepileptogenic hippocampus. These results have significant implications for the identification of the MRI-normal hippocampus that requires surgical intervention and preservation of the nonepileptogenic hippocampus.

Purpose: Photosensitivity is a phenomenon that may be elicited by standardized intermittent photic stimulation during EEG recording and is detected more frequently in children and adolescents. Nevertheless, at our Epilepsy Center, we routinely assess photosensitivity in all newly referred adult patients. In this investigation, we sought to address the diagnostic yield under the prerequisites described.

Methods: We reanalyzed all routine EEG recordings among referrals to the department of adults during the first six months of 2019, including a simultaneous video that is always coregistered in our center. The prevalence of abnormal findings during photic stimulation was assessed.

Results: Intermittent photic stimulation was performed on 344 patients. Photoparoxysmal response were detected in five subjects (1.5%). All patients were female. Four patients were diagnosed with idiopathic generalized epilepsy, and one with Doose syndrome. Photomyogenic responses were recorded in 1.1% and only in patients with psychogenic nonepileptic seizures. In two subjects with psychogenic nonepileptic seizures, the typical seizure was provoked by intermittent photic stimulation (8.7% of all subjects with psychogenic nonepileptic seizures in this cohort). Photoparoxysmal response was not detected in any subject with focal epilepsy, syncope, or other nonepileptic paroxysmal events. In every case of photoparoxysmal responses, increased photosensitivity had already been reported before recording.

Conclusions: In our study, photoparoxysmal responses was a rare phenomenon among adults with a preponderance of females and idiopathic generalized epilepsies. Intermittent photic stimulation may be helpful in provoking typical psychogenic nonepileptic seizures and thus abbreviate the diagnostic process. Provided a careful history, routine intermittent photic stimulation in adults with epilepsy does not appear to be mandatory.