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: To determine if incorporating neuroanatomic or intersubject variation in the occurrence rate of intracranial high-frequency oscillations improves its diagnostic performance for localization of epileptogenic zone (EZ).

Methods: Five minutes of awake stereo-electroencephalography data from 59 patients were analyzed. High-frequency oscillations were analyzed using three different normalization methods: rate per minute, by neuroanatomic region across the patient population, and patient-wise. Generalized linear mixed effects models were trained in patients with good seizure outcomes after epilepsy surgery (higher confidence in the clinical localization of EZ) and tested in patients with poorer outcomes (validation set approach).

Results: The generalized linear mixed model with region-wise normalization across the patient population best localized the EZ (highest area under the curve 0.69), closely followed by the rate per minute (0.68). In the test subgroup, the optimal generalized linear mixed model predicted EZ in individual patients with an accuracy of 0.18 to 0.86, sensitivity of 0.05 to 1.00, and specificity of 0.12 to 0.95. In patients with poorest performance of the generalized linear mixed model, although the electrode contacts within EZ were correctly identified, there was a high number of false positives (model-predicted electrode contacts lying outside clinically ascertained EZ). Model performance varied across neuroanatomic regions, with the highest accuracy in the medial/orbital frontal (0.8), lateral temporal (0.78), and lateral parietal (0.76) regions.

Conclusions: Normalizing the high-frequency oscillation occurrence rate by neuroanatomic region improves its diagnostic performance as an interictal biomarker of EZ location. High-frequency oscillations are more likely to reliably identify electrode contacts within EZ in medial/orbital frontal lobe and temporal neocortex.

Purpose: Outpatient seizure monitoring is crucial for optimizing treatment strategies in epilepsy; however, traditional approaches such as seizure diaries and wearables have limitations in accuracy and practicality. This study evaluated the adherence and utility of an implanted subcutaneous EEG monitoring system in patients with focal temporal lobe epilepsy.

Methods: At a tertiary epilepsy center, patients with focal epilepsy received a subcutaneous two-channel EEG system for ultra-long-term monitoring. The system includes a subcutaneously implanted electrode for data recording and a behind-the-ear companion device for the power supply and data transmission. Patient adherence to the device was evaluated using generalized estimating equations, considering sex, daytime/nighttime periods, age, and temporal course of measurements. The correlations between adherence and electrographic or diary-recorded seizures were also assessed.

Results: Fifteen adult patients (mean age: 45.6 years, 6 females) were monitored for an average of 200.6 days, with 416 electrographic seizures confirmed in 13 patients. The median adherence was 89.3% (interquartile range, [75.6%, 93.4%]), with females showing significantly higher adherence than males ( β , -1.1600; P = 0.049). Seizure diary reporting sensitivity and precision were 20.8% and 56.4%, respectively, compared with confirmed electrographic seizures. Adherence correlated positively with confirmed electrographic seizures ( r , 0.40; P, 0.004), but not with diary reports ( r , -0.22; P, 0.13).

Conclusions: Patients using the subcutaneous EEG system demonstrated high adherence and reliable seizure monitoring, suggesting that it could serve as a valuable tool for managing focal epilepsy in clinical practice.

Purpose: The aim of this study is to develop an intraoperative olfactory monitoring system using olfactory evoked potential produced by electrical stimulation. Furthermore, the study seeks to ascertain the feasibility and safety of olfactory evoked potential. This study lays the groundwork for safeguarding olfactory function during surgical procedures.

Methods: We provided a detailed description of the procedure involving electrical stimulation of the olfactory mucosa to induce olfactory evoked potentials during endonasal endoscopic surgery under general anesthesia. This study enrolled 20 patients undergoing endonasal endoscopic surgery. Before surgery, all patients reported no olfactory complaints, and T&T olfactometry did not detect any olfactory disorders. Olfactory evoked potentials were recorded from various regions of the nasal mucosa and followed by analysis of waveform differentiation, latencies, and amplitudes.

Results: Typical "N1-P1-N2" three-phase waves, consistent with the waveforms of olfactory evoked potentials recorded in previous studies, were collected from the olfactory mucosa in each case. No significant alteration was observed in the patients' olfactory function pre- and postsurgery. The latencies of the "N1-P1-N2" waves recorded during the operation were 12.2 ± 6.9 ms, 28.9 ± 10.0 ms, and 47.1 ± 11.6 ms, respectively, whereas the amplitudes of the "N1-P1" and "P1-N2" waves measured 0.9 and 0.6 μV, respectively.

Conclusions: Intraoperative olfactory monitoring through olfactory evoked potential produced by electrical stimulation is achievable and safe.

Purpose: This study aimed to assess the diagnostic utility of the medial dorsal cutaneous (MDC) nerve and the medial dorsal cutaneous-to-radial amplitude ratio (MDRAR) in diabetic polyneuropathy (DP).

Methods: Seventy-four patients clinically diagnosed with DP and 40 healthy controls underwent nerve conduction studies (NCS), including sural, radial, medial plantar (MP), and MDC sensory recordings. Most patients had recent-onset, mild-to-moderate DP. Sural-to-radial amplitude ratio (SRAR), medial plantar-to-radial amplitude ratio (MPRAR), and MDRAR were calculated. Minimal tibial F-wave latencies were height-corrected, and sural amplitudes were age-corrected. Diagnostic cut-off values were established by ROC analysis. Values below the cut-off, as well as absent responses, were classified as abnormal, and sensitivity and specificity were calculated.

Results: A sural SNAP <6 µV demonstrated 42% sensitivity and 100% specificity. A minimal tibial F-wave latency ≥50 ms had 61% sensitivity and 100% specificity. For SRAR, a cut-off ≤0.40 yielded 49% sensitivity and 97% specificity; the 0.34 cut-off produced 38% sensitivity and 100% specificity, while the 0.21 cut-off yielded 19% sensitivity and 100% specificity. MPRAR and MDRAR demonstrated higher sensitivities (61 and 68%) but lower specificities (82 and 75%). Sural responses were obtainable in 82% of patients, whereas MP and MDC responses were recorded in 50 and 39%, respectively.

Conclusions: MDRAR did not provide additional diagnostic value as a stand-alone electrophysiological parameter; however, bilateral absence of MDC responses emerged as a valuable marker of early distal involvement in DP. Further studies in selected patient groups are warranted to clarify the diagnostic contribution of MDRAR, particularly in early-stage and predominantly axonal forms of DP.

Introduction: Delirium is a common and serious complication in critically ill patients, associated with higher mortality, prolonged intensive care unit (ICU) stays, and cognitive impairments. Furthermore, renal dysfunction is a well-recognized risk factor for delirium in the ICU. Although previous studies have explored the neurophysiologic characteristics of delirium, few have examined brain activity during active delirium episodes. To address this gap, this study aimed to use mismatch negativity (MMN)-an electrophysiologic marker of the brain's automatic ability to detect environmental changes-to deepen the understanding of the pathophysiology and phenomenology of delirium in ICU patients with renal dysfunction.

Methods: An auditory oddball paradigm, consisting of frequent standard tones and infrequent deviant tones, was presented to critically ill patients with renal dysfunction during event-related potential recordings. MMN was obtained by subtracting the event-related potential response to deviant stimuli from that of standard stimuli and was compared between patients with and without delirium. In addition, the authors examined the relationships between MMN, cognitive function, and disease severity. Finally, they assessed whether MMN could predict key clinical outcomes at ICU discharge.

Results: ICU patients with delirium exhibited significantly prolonged MMN latencies compared with those without delirium (P = 0.005, effect size = 0.67). Moreover, more delayed MMN latencies showed a trend toward an association with greater delirium severity. However, MMN did not predict key clinical outcomes on ICU discharge.

Conclusions: Critically ill patients with renal dysfunction exhibit prolonged MMN latencies during delirium episodes compared with those without delirium, suggesting altered neural processing in this population.

Purpose: The thalamus is a target for neurostimulation in epilepsy based on its extensive reciprocal connectivity with the cortex and subcortical areas and putative participation in a broader seizure network. In focal neocortical onset epilepsies, costimulation of the cortex and thalamus may provide an opportunity to modulate two nodes of a seizure network. Given the central role of the thalamus in sleep oscillations and regulation of consciousness, as well as the fundamental interaction between sleep and epilepsy, consideration of sleep/wake cycles may be important when treating patients with corticothalamic stimulation.

Methods: This single-center retrospective study included 30 patients with focal seizures treated with cortical and thalamic responsive neurostimulation (NeuroPace RNS® System). The thalamic leads were implanted in the centromedian, pulvinar, mediodorsal, or anterior nucleus depending on clinical characteristics, semiology, and localization testing. Changes in the average power of predefined frequency bands in the interictal thalamic iEEGs were evaluated in ambulatory daily recordings collected postimplant.

Results: Two clusters in frequency characteristics were clearly distinguished by time of day (daytime vs. nighttime). The time series evolution for points in the two clusters was not generally correlated, and sometimes diverged. Clusters were more prominent on some channels than others, even between adjacent electrode contacts on the same leads, perhaps reflecting the anatomic location.

Conclusions: These results suggest that thalamic iEEG data can potentially be used to identify wake/sleep states electrographically without traditional sleep studies. This could enable state-dependent neuromodulation therapy. The observed changes in sleep/wake clusters over time could represent neuromodulation-driven changes in thalamocortical networks and warrant further investigation.

Purpose: Antiseizure medication is the first-line treatment for new-onset-epilepsy, leading to seizure control in 70% to 80% of patients. An early identification of an appropriate treatment is extremely important to avoid seizure relapses, and biomarkers for relapse risk are needed to avoid any delays. The authors investigated electroencephalography (EEG)-based brain connectivity and microstates between patients with new-onset epilepsy who responded to treatment (SZ-FREE) and patients who relapsed (SZ-REL), to link potential differences to treatment response.

Methods: Sixty-two patients with new-onset epilepsy for whom an EEG was performed before treatment initiation, after a first seizure event. The authors computed EEG connectivity for delta, theta, alpha, beta, and gamma frequencies, and microstates. By performing mixed-model analyses, the authors tested connectivity differences across frequency bands and microstate characteristic changes between SZ-FREE and SZ-REL.

Results: After treatment, 51 patients remained seizure free while 11 relapsed within 6 months. The authors observed a significant interaction between frequency bands and groups (P < 0.001). Post hoc tests showed delta (P = 0.006) and theta (P = 0.012) decreases, and alpha increases (P < 0.001) for patients with SZ-REL compared with patients with SZ-FREE. Microstate C had a significantly higher global explained variance for patients with SZ-REL than patients with SZ-FREE (P = 0.021), while microstates A occurred more frequently in SZ-REL (P = 0.031).

Conclusions: EEG connectivity and microstates in the first EEG within 24 hours after the initial seizure hold valuable information related to the drug responsiveness in patients with new-onset epilepsy.

Significance: EEG connectivity and microstates are potential markers of treatment response.

Purpose: Aim of the study was to examine the associations between abductor pollicis brevis (APB) muscle stiffness evaluated by shear wave elastography and electrodiagnostic study findings in patients with carpal tunnel syndrome. The association between shear wave elastography and APB muscle echogenicity was also examined.

Methods: This prospective study included patients who were referred to electrodiagnostic studies because of upper limb symptoms. The electrodiagnostic studies consisted of nerve conduction studies and needle-electromyography. Abductor pollicis brevis muscle shear wave velocity was measured, and muscle echogenicity assessed using the Heckmatt grading scale.

Results: In total, 97 hands were included in the nerve conduction studies. Of these, 53 APB muscles were further examined with needle-electromyography. Shear wave velocity correlated positively with the neurophysiologic severity of carpal tunnel syndrome ( r = 0.449, P = 0.028, N = 26). Mean shear wave velocity was faster in the APB muscles with neurogenic findings (mean 2.72 m/second, ±SD 0.36) than muscles with normal findings (2.48 m/second, ±SD 0.34, P = 0.036). In receiver operating characteristic analysis, the best shear wave velocity cutoff value was 2.66 m/second. With this cutoff value, the sensitivity was 0.692, while the 1-specificity was 0.233. Only seven APB muscles showed increased echogenicity.

Conclusions: Shear wave velocity of APB muscle is positively associated with the neurophysiologic severity of carpal tunnel syndrome. Carpal tunnel syndrome-related axonal damage also seems to increase shear wave velocity in APB muscle; however, according to the receiver operating characteristic analysis, the method is not yet suitable for clinical use to define muscle denervation. The findings of this study show that shear wave elastography has potential as an additional clinical tool in the diagnostics of carpal tunnel syndrome.

Purpose: Continuous electroencephalography (cEEG) is used in the critical care setting for seizure detection and treatment, sedation management, and ischemia detection. Further evidence is needed to support whether early cEEG use can improve outcomes. We examined whether time from admission to cEEG initiation affects outcomes.

Methods: This is a single-center cohort study of critically ill adults (age > 18 years) who underwent cEEG monitoring within 7 days of admission from January to December 2019. Patients with anoxic brain injury were excluded. Time (hours) from admission to cEEG was recorded. Outcomes were in-hospital mortality and poor discharge modified Rankin Score (4-6). Results are reported as median [quartile range] and odds ratio (OR) [confidence intervals, CI].

Results: In total, 464 patients met eligibility. Median time to cEEG was 23 hours [13, 52]. On multivariable analysis, increasing time to cEEG was associated with discharge mortality (OR, 1.006 [CI, 1.0002-1.013], 0.1%/hour [CI, 0.02-0.2]) and poor outcome (OR, 1.013 [CI, 1.005-1.020], 0.2%/hour [CI, 0.07-0.3]). Median time to cEEG initiation in patients with clinical concern for seizures/status at presentation ( n = 121) was 12 hours [6, 17] and in patients without clinical concern for seizures at presentation ( n = 343) was 31 hours [18, 66]. In patients without clinical concern for seizures/status epilepticus at presentation, time to cEEG continued to be associated with mortality (OR, 1.007 [CI, 1.001-1.014)] and poor outcome (OR, 1.012 [CI, 1.003-1.021]).

Conclusions: Increasing time to cEEG initiation was associated with higher mortality and worse outcomes. We hypothesize earlier cEEG results in timely interventions including treatment escalation and de-escalation that may improve outcomes.