Journal of Clinical Neurophysiology最新文献

Purpose: Patients with Alzheimer's dementia (AD) who do not have a history of epilepsy have a higher frequency of subclinical epileptiform discharge (SED) than healthy individuals. This meta-analysis aims to investigate the frequency of SED in patients with AD using different EEG protocols and to compare SED rates between early- and late-onset AD.

Methods: This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. We searched various databases until January 2024 for studies reporting the frequency of SED in patients with AD who did not have a history of epilepsy. A meta-analysis was conducted using a random-effects model.

Results: Thirteen studies involving 1,373 patients with AD were analyzed. The patients had a mean age of 71.2 years, and 59.3% were women. The pooled SED rate was found to be 18.3%. The SED rate was higher with extended EEG protocols (26.7%) than with routine EEG protocols (12.1%). It was also observed that patients with early-onset AD had higher SED rates with routine EEG protocols (14.4%) and extended EEG protocols (43.9%) than those with late-onset AD (10.5 and 21.3%, respectively). Furthermore, patients with AD had a 3.55 relative risk (P < 0.001) of SED compared with healthy controls. Specifically, patients with early-onset AD showed a significantly higher risk of developing SED than those with late-onset AD (relative risk, 4.48; P < 0.001).

Conclusions: Subclinical epileptiform discharge frequency was high in patients with AD, particularly in those with early onset AD.

Purpose: These American Clinical Neurophysiology Society technical standards suggest best practices for electrical stimulation mapping (ESM) with subdural and stereotactic depth electrodes for seizure induction and mapping of brain function.

Methods: A working group was convened from American Clinical Neurophysiology Society membership with expertise in ESM. PubMed searches were performed to identify pertinent peer-reviewed literature. Recurrent meetings reviewed progress, built consensus by discussion, and developed evidence-based recommendations to the extent possible.

Recommendations: Stimulators used for ESM should have sufficient dynamic range, ability to interrupt a stimulus train, and ictal disrupt mechanism(s). Charge density should be calculated for the specific electrodes and ESM settings, the maximum safe limits being 52 to 57 μC/cm2/phase for subdural electrodes and not established for stereotactic depth electrodes. Subdural ESM for functional mapping is typically performed at 50-Hz pulse frequency, 200- to 300-µs pulse width, 2- to 8-s train duration, and 1- to 20-mA current strength. Stereo ESM is commonly performed using 2 different pulse frequencies: 1 Hz (300-500 µs pulse width, train duration up to 30 s, and often a constant current of 3-5 mA), and 50 Hz (100-500 µs pulse width, train duration 2-8 s, and 0.5-10 mA current intensity).

Conclusions: This guideline provides technical standards for the performance of ESM, which will likely evolve over time with advances in technology and additional evidence (also see Graphical Abstract).

Purpose: To understand the current state of epilepsy surgery education delivered to epilepsy fellows in the United States.

Methods: An online survey focused on characteristics of epilepsy surgery education was distributed to all 93 epilepsy fellowship program directors listed on the ACGME website (accessed in May 2022). Programs were stratified per the number of fellows currently enrolled: 0 to 3 (group A) and ≥4 (group B).

Results: Forty-one of 93 (44%) epilepsy fellowship programs were included in the study. The average number of resective surgeries, ablations, or corpus callosotomies per year was mostly 0 to 30 (54%) in group A and mostly >30 (80%) in group B (P = 0.05). The average number of intracranial implantations per year was mostly 0 to 20 (58%) in group A and mostly >20 (80%) in group B (P < 0.05). The average number of neurostimulation implantations per year was 15 (range 0-90; vagal nerve stimulation), 7 (range 0-25; responsive neurostimulation), and 4 (range 0-10; deep brain stimulation). In 78% of programs, fellows are not required to present a minimum number of epilepsy surgery cases in multidisciplinary conference before graduation. Roughly half of programs (51%) reported not using objective measures to assess fellow competency in epilepsy surgery.

Conclusions: Our results suggest significant variability in epilepsy surgery volume and, consequently, fellow exposure to surgical cases and lack of standardized, objective measures in fellow teaching and assessment in the field of epilepsy surgery across programs in the United States. We advocate development of a core epilepsy surgery curriculum including minimum standards at the national level.

Purpose: This study aimed to establish reference values for laryngeal adductor reflex latency and amplitude under general anesthesia using a noninvasive technique with commercially available electromyographic endotracheal tubes.

Methods: This retrospective observational study included 380 patients undergoing head and neck surgery. The inclusion criteria were recording the laryngeal adductor reflex from the nonsurgical side and the absence of pathology in the recurrent laryngeal nerve. Measurements were taken before incision and surgical completion.

Results: The R1 component medians for the latency and amplitude were 20 ms and 448 µV for the right and 22 ms and 425 µV for the left LARs, respectively. There were significant differences in the R1 latencies between the sides. Quantile regression models revealed that 95th percentile amplitudes exceeded 400 µV, whereas 5% of our data set surpassed 600 µV. The R2 component was present in 26% of patients initially but decreased to 8% at surgical conclusion. The percentage difference between the median R1 value at the end of the surgery, compared with the opening value, was up to 4% for latency and 10% for amplitude.

Conclusions: The R1 component of the laryngeal adductor reflex remains a reliable tool for intraoperative neuromonitoring. This is the largest study to provide reference values for laryngeal adductor reflex, aiding future diagnostic applications in head and neck surgeries.

Introduction: EEG source localization is an established technique for localizing scalp EEG in medically refractory epilepsy but has not been adequately studied with intracranial EEG (iEEG). Differences in sensor location and spatial sampling may affect the accuracy of EEG source localization with iEEG. Corticocortical evoked potentials can be used to evaluate EEG source localization algorithms for iEEG given the known source location.

Methods: We recorded 205 sets of corticocortical evoked potentials using low-frequency single-pulse electrical stimulation in four patients with iEEG. Averaged corticocortical evoked potentials were analyzed using 11 distributed source algorithms and compared using the Wilcoxon signed-rank test ( P < 0.05). We measured the localization error from stimulated electrodes and the spatial dispersion of each solution.

Results: Minimum norm, standard low-resolution electromagnetic tomography (sLORETA), LP Norm, sLORETA-weighted accurate minimum norm (SWARM), exact LORETA (eLORETA), standardized weighted LORETA (swLORETA), and standardized shrinking LORETA-FOCUSS (ssLOFO) had the least localization error (13.3-15.7 mm) and were superior to focal underdetermined system solver (FOCUSS), logistic autoregressive average (LAURA, and LORETA, 17.9-21.7, P < 0.001). The FOCUSS solution had the smallest spatial dispersion (7.4 mm), followed by minimum norm, L1 norm, LP norm, and SWARM (20.8-28.3 mm). Gray matter stimulations had less localization error than white matter (median differences 3.1-6.1 mm) across all algorithms except SWARM, LORETA, and logistic autoregressive average. A multivariate linear regression showed that distance from the source to sensors and gray/white matter stimulation had a significant effect on localization error for some algorithms but not SWARM, minimum norm, focal underdetermined system solver, logistic autoregressive average, and LORETA.

Conclusions: Our study demonstrated that minimum norm, L1 norm, LP norm, and SWARM localize iEEG corticocortical evoked potentials well with lower localization error and spatial dispersion. Larger studies are needed to confirm these findings.

Purpose: This study reports our center's initial experience with the use of low-frequency stimulation in provoking stimulation-induced seizures (SIS) in children with drug-resistant epilepsy undergoing stereo-EEG evaluations.

Methods: This retrospective study enrolled children aged 2 to 18 years with drug-resistant focal epilepsy who underwent stereo-EEG evaluation and extraoperative direct electrical cortical stimulation to elicit seizures. The low-frequency stimulation parameters consisted of biphasic square waveforms at frequency of 1 Hz, pulse width 1 millisecond, current 1 to 3 mA, and train duration of 20 seconds. Various epilepsy-related, imaging, neurophysiology, and surgery-related variables were collected and summarized.

Results: Fourteen children (mean age 13 years; 57.1% girls) were included, 10 of whom had unilateral stereo-EEG coverage. Cortical stimulation for provoking seizures was performed after a median of 5 days after electrode implantation. The median number of electrode-contacts stimulated per patient was 42. Four patients (28.6%) experienced habitual SIS (all extratemporal). The etiology in three patients was focal cortical dysplasia. Interictal high-frequency oscillations at electrode-contacts provoking SIS were observed in three cases (75%). Two of these individuals (50%) had class 1 International League Against Epilepsy seizure outcome at last follow-up, after the resection of the brain regions generating SIS.

Conclusions: Low-frequency (1-Hz) stimulation could provoke habitual SIS in nearly one-fourth of children with focal epilepsy undergoing stereo-EEG monitoring. This study provides a limited pediatric experience with the low-frequency cortical stimulation and SIS.

Purpose: Contraction-induced H reflexes are a late neurophysiologic response elicited with submaximal nerve stimulation during isometric muscle contraction. Mediated by spinal pathways, like other H reflexes, their use has remained somewhat limited despite a long history of development dating back to the original description by Hoffman. There is a paucity of data on normal reference ranges, which this article aims to add to.

Methods: Contraction-induced H reflexes were elicited from the first dorsal interosseous, flexor carpi radialis, and tibialis anterior bilaterally in 100 healthy volunteers. Reference values, including side-to-side variation, were calculated. Pearson test and multiple regression were used to evaluate the relationship of H-reflex latency to height, age, and sex of participants.

Results: The mean onset latencies of 28.00, 17.44, and 31.10 ms were seen for first dorsal interosseous, flexor carpi radialis, and tibialis anterior muscles, respectively. The calculated allowable side-to-side latency difference in individual participants was 3 to 4 ms. A correlation to participant height was seen.

Conclusions: This work provides normal reference values of contraction-induced H reflexes to three muscles, including allowable side-to-side variation. The latter suggests that bilateral testing evaluating for asymmetry within an individual is likely to be optimally sensitive. The relationship to height is also confirmed.

Purpose: To identify and characterize events of deterioration in intraoperative neuromonitoring data during correction procedures for thoracic and lumbar abnormal spinal curvature in young patients.

Methods: Records of 1,127 cases were retrospectively reviewed to identify events with deterioration of the neuromonitoring data. General etiological and demographic variables were summarized, and neuromonitoring events were studied and characterized.

Results: Adolescent idiopathic cases were associated with female dominance and older age. Nonadolescent idiopathic cases were associated with a higher rate of neuromonitoring events. The neuromonitoring events evolved during the different procedural stages, were primarily reflected in the motor-evoked potential data and affected a range of neural structures to varying degrees. Most of the events were resolved, partially or completely, following a corresponding intervention by the surgical team, before the end of the procedure. Significant immediate weakness of the lower extremities was demonstrated in patients with unresolved neuromonitoring events, most of them were nonadolescent idiopathic patients.

Conclusions: Neurophysiological monitoring enables the intraoperative assessment of the integrity of neural pathways and allows the detection of surgery-related impending neural injuries. Neuromonitoring contributes to intraoperative decision making, either when data are uneventful and allow confident continuation or when data deteriorate and lead to corresponding intervention. Further awareness should be paid to the vulnerable characteristics of the patient, surgery course, and neuromonitoring data. Proper interpretation of the neuromonitoring data, together with corresponding intervention by the surgeon when necessary, has the potential to reduce postoperative neurological insults and improve clinical outcomes.

Purpose: The aim of this study was to establish normative data for the sural-to-radial nerve amplitude ratio (SRAR) and develop a quantile regression model for individualized cutoff values.

Methods: A cohort of 68 healthy individuals (36 female participants) aged 20 to 59 years was recruited. Sensory nerve conduction studies were conducted to measure sural and radial sensory nerve action potential amplitudes. Quantile regression analysis was used to determine the fifth percentile of SRAR after adjusting for age, sex, and other demographic variables.

Results: This study found significant differences in body height and weight between the sexes, with radial sensory nerve action potential being higher in female participants. The sural-to-radial nerve amplitude ratio was negatively correlated with age ( r = -0.3, p = 0.007) and showed significant sex differences. The final regression equation, SRAR = 0.519 - 0.006 × age + 0.046 × sex (1 = male, 0 = female), was developed for the fifth percentile cutoff, accounting for age and sex.

Conclusions: This study establishes normative SRAR data and introduces a novel quantile regression approach to determine individualized cutoff values. Age and sex are critical factors for SRAR variation, necessitating tailored diagnostic criteria for neuropathy assessment. This model enhances diagnostic accuracy and potentially reduces misdiagnosis in clinical settings. Further research is recommended to validate the clinical applicability of SRAR across different types of neuropathies.

Summary: Precise localization of peripheral nerve injuries and evaluation of their prognosis based on clinical and electrodiagnostic examinations are particularly challenging in the acute phase. High-resolution ultrasound (HRUS) may offer a viable and cost-effective imaging option for assessing the morphology of nerve injuries. Consequently, a systematic review and meta-analysis of studies on the use of ultrasound for diagnosing traumatic nerve injuries were conducted. A total of 15 studies were included, reporting the most recent findings on using HRUS in the diagnosis of traumatic nerve injury. These studies assessed the diagnostic test accuracy of ultrasound for the detection of traumatic nerve injury in 272 participants, with the cross-sectional area at the site of traumatic nerve injury also reported in 1,249 participants. The pooled sensitivity and specificity of the included studies were 92% confidence interval (CI) (0.89-0.95) and 86% CI (0.82-0.89), respectively. The positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 13.76 CI (1.41-134.34), 0.08 CI (0.03-0.18), and 286.23 CI (21.22-3,860.40), respectively. In the summary of the receiver operating characteristic curve, the area under the curve was 0.986, and the Q* index was 0.949. Based on the current literature, HRUS has shown promising results in addition to its availability and feasibility. HRUS can serve as a valuable complement to clinical and electrodiagnostic examinations for diagnosing traumatic peripheral nerve injuries. Further research is recommended to better understand the ultrasound characteristics of these injuries.