Clinical Neurophysiology最新文献

Objective: Non-invasive neuromodulation techniques, particularly transcranial direct current stimulation (tDCS), are promising for drug-resistant epilepsy (DRE), though the mechanisms of their efficacy remain unclear. This study aims to (i) investigate tDCS neurophysiological mechanisms using a personalized multichannel protocol with magnetoencephalography (MEG) and (ii) assess post-tDCS changes in brain connectivity, correlating them with clinical outcomes.

Methods: Seventeen patients with focal DRE underwent three cycles of tDCS over five days, each consisting of 40-minute stimulations targeting the epileptogenic zone (EZ) identified via stereo-EEG. MEG was performed before and after sessions to assess functional connectivity (FC) and power spectral density (PSD),estimated at source level (beamforming).

Results: Five of fourteen patients experienced a seizure frequency reduction > 50 %. Distinct PSD changes were seen across frequency bands, with reduced FC in responders and increased connectivity in non-responders (p < 0.05). No significant differences were observed between EZ network and non-involved networks. Responders also had higher baseline FC, suggesting it could predict clinical response to tDCS in DRE.

Conclusions: Personalized multichannel tDCS induces neurophysiological changes associated with seizure reduction in DRE.

Significance: These results provide valuable insights into tDCS effects on epileptic brain networks, informing future clinical applications in epilepsy treatment.

Objective: Autism is linked to a strong need for sameness and difficulties in social communication, associated with atypical brain responses to voices and changes. This study aimed to characterize neural adaptation in autistic adults using a Roving paradigm and assess how vocal vs. non-vocal, as well as neutral vs. emotional sounds, influence this adaptation.

Methods: Neural adaptation was measured in 20 autistic and 20 non-autistic adults using a Roving paradigm, where sounds were repeated 4, 8, or 14 times. Neural responses and Repetition Positivity (RP) amplitudes were analyzed as indices of adaptation.

Results: RP amplitudes showed no significant differences between groups for vocal or non-vocal sounds, but adaptation dynamics varied. Non-autistic adults adapted more quickly to non-vocal (5-8 repetitions) compared to vocal sounds (12-14 repetitions). In contrast, autistic adults adapt faster to vocal than to non-vocal sounds. Moreover emotional prosodic content influenced RP amplitude in autistic adults only, suggesting heightened sensitivity to emotional cues in social contexts.

Conclusions: The study highlights how atypical neural adaptation in autism how emotional content impacts social communication deficits. These insights enhance understanding of autism-related adaptation challenges.

Objective: Seizure suppression using the neurofeedback (NFB) method by self-regulation of scalp-recorded slow cortical potential (SCP) is effective for patients with refractory focal epilepsy. However, the prolonged training period required prevents it from wider implementation as the standard treatment in clinical practice. Therefore, we examined whether it would be appropriate to shorten the training period, in spite of the small number of patients.

Methods: 12 patients participated the NFB training. 1 course of NFB training consisted of 35 sessions divided into 2 phases. After each phase we evaluated whether each patient acquired NFB control, and seizure reduction was assessed compared to that before training.

Results: Of 11 patients who completed the first training phase, 4 showed reduced post-training seizure frequency, of whom 3 could regulate the SCP polarity (NFB control). Of the remaining 7, 2 acquired NFB control during the second training phase but seizure frequency did not decrease. Furthermore, the other 5 did not acquire NFB control, and seizure frequency did not decrease.

Conclusions: Patients who acquired NFB control within a short period, i.e., 3 weeks, were more likely to exhibit a lower post-training seizure frequency.

Significance: SCP self-regulation can be acquired within a short period and is associated with seizure reduction.

Objective: Deep brain stimulation (DBS) targeting the subthalamic nucleus (STN) is a common treatment for motor symptoms of Parkinson's disease but its influence on non-motor symptoms is less clear. Sleep spindles are known to be reduced in patients with Parkinson's disease, but the effect of STN DBS is unknown. The objective of our study was to address this knowledge gap.

Method: Polysomnograms were recorded for three consecutive nights in 15 patients with advanced Parkinson's disease (11 male, 4 female; age: 53-75 years), including at least one night each of unilateral STN DBS stimulation ON and OFF. Stimulation ON was set to 70 % of clinical amplitude to mitigate sleep being altered via changing motor symptoms or due to patient awareness of stimulation. Sleep spindles were detected in electroencephalogram (EEG) data by two previously published, validated automated sleep spindle detection algorithms: Ferrarelli et al. (2007) and Martin et al. (2013).

Results: Sleep spindle density was higher during stimulation ON than OFF nights in 11 of 12 subjects using either sleep spindle detection algorithm (p<=0.01, Wilcoxon rank sum). Stimulation ON versus OFF had no statistically significant effect on sleep spindle duration or amplitude.

Conclusion: Our analysis indicates that a single night of sub-optimal STN stimulation significantly increases sleep spindle density in Parkinson's disease patients.

Significance: These results further our understanding of how DBS impacts non-motor symptoms of Parkinson's disease.

Objective: To explore the ultrasonographic characteristics of SLE-related peripheral neuropathy (PN) using nerve ultrasound.

Methods: Patients with SLE were recruited consecutively between December 2022 and June 2023. Detailed clinical assessment and nerve ultrasound were conducted on each SLE patient and healthy control (HC) at predetermined sites of peripheral nerves. The upper limit of the CSA for each nerve location was defined as 95th percentile in healthy controls for the identification of nerve enlargement. Nerve conduction studies (NCS) and relevant ancillary examinations were conducted on all SLE patients for comparisons.

Results: A total of 32 SLE female patients and age- and gender-marched 52 HC were finally recruited. At M6 (P = 0.041) point of median nerve, U1 (P < 0.001) and U6-10 (P < 0.001, =0.008, <0.001, <0.001, <0.001, respectively) points of ulnar nerve, the CSA in SLE patients were remarkably higher than that in HC. Mild and moderate nerve enlargement were detected in 12 and 20 SLE patients, respectively. Only 12 tested nerves showed both axonal damage in electrophysiological studies and nerve enlargement under ultrasound.

Conclusion: Nerve enlargement was extremely common in SLE patients, mainly in the forms of mild to moderate and focal thickening in upper limbs. There was significant inconsistency between NCS and ultrasound in detecting peripheral nerve involvement and a combined examination using NCS and nerve ultrasound might be more effective in detecting SLE-related PN.

Objective: To examine the blood oxygen level-dependent (BOLD) responses in the default mode network (DMN) and subcortical regions in relation to epileptic events in scalp EEG and intracranial EEG (iEEG).

Methods: We retrospectively compared BOLD responses in the DMN and subcortical regions to interictal epileptiform discharge (IED) characteristics of the scalp and iEEG in consecutive patients with focal epilepsy. All voxels were used as the denominator to assess the positive and negative BOLD ratios in each region, and the percentage of voxels with significant activation or deactivation was assessed.

Results: Seventy-one EEG-fMRI studies were included. The widespread IED group showed a higher negative BOLD ratio in the DMN than did the focal IED group. Spike and ripple spreads in iEEG positively correlated with a positive BOLD ratio in the DMN and subcortical regions and a negative BOLD ratio in the DMN. Fast ripple spread showed no correlation with the BOLD ratio in any region.

Conclusions: IEDs affect local regions, as well as distant neocortical (DMN) and subcortical regions, depending on their localization and characteristics.

Significance: Our findings showed both positive and negative IED-related BOLD responses in subcortical regions and new evidence of network dysfunction related to focal epileptic activity.

Objective: Interictal cognitive disturbances are frequent in patients with focal epilepsies and the links with alteration of resting state brain oscillations are not well known. Changes in theta oscillations, may contribute to cognitive impairment. This study aimed to investigate whether changes in theta activity are related to cognitive disturbances.

Methods: Retrospective data of 23 patients with temporal/frontal lobe epilepsy were included. Theta connectivity, power and interictal spikes rate from five-minute interictal resting state stereoelectroencephalography datasets were computed. Cognitive performances were assessed by Wechsler Intelligence Scale (WAIS-IV) and Weschler Memory Scale (WMS-III). Linear regression was performed to evaluate effect of interictal activity and seizure related parameters on cognitive scores.

Results: WAIS-IV working memory score in patients with epilepsy showed negative correlation with frontotemporal theta connectivity (F(1,17) = 5,239, p = 0,036, R² = 0,200, β = -0,497). Moreover, theta connectivity was correlated with mesial temporal spike rate and theta power (F(2,17) = 10,967, p = 0,001, adj.R² = 0,540).

Conclusions: Patients with focal epilepsy often encounter compromised cognitive functions, particularly notable in the domain of working memory. This impairment might be attributed to physiological mechanisms involving increased theta connectivity within the frontotemporal regions and interictal spiking.

Significance: Our study highlights the relation between theta connectivity and working memory impairments in patients with focal epilepsy.

Objective: Assessment of cortical function with threshold tracking transcranial magnetic stimulation (TT-TMS) has developed as a biomarker to inform disease pathophysiology, particularly in neurodegenerative disease and dementia. At present, a fully integrated testing system does not exist. To advance clinical utility, and to streamline software design to integrate with diagnostic approaches in an outpatient setting, the present series of studies assessed the effects of altering diagnostic paradigms to measure interstimulus interval (ISI) including serial ascending [T-SICIs] and parallel [T-SICIp] methodologies as measures of cortical motor function (the MagXite software).

Methods: Cortical excitability was assessed in 30 healthy controls with a figure-of-eight coil, using an integrated approach compared to previously established experimental paradigms. Motor evoked responses were recorded over the contralateral abductor pollicis brevis muscle. Short interval intracortical inhibition (SICI) was recorded with each testing paradigm and validated in a healthy control cohort.

Results: The integrated system determined a robust measure of T-SICIs between ISI 1-to-7 ms (16.6 ± 2.2 %) that was comparable to previously established testing paradigms (P = 0.34), but greater than T-SICIp (MagXite 10.7 ± 1.5 %, P = 0.016; Sydney TT-TMS 8.7 ± 1.4 %, P = 0.03). SICI peaks at ISI 1 and 2.5-to-3 ms were evident with both protocols. Significant correlations were evident between mean T-SICIs-_MagXite and T-SICIp-_MagXite (R = 0.599, P < 0.001).

Conclusion: The present series validates a fully integrated motor cortical functional assessment to provide reproducible measures of SICI, with data obtained for intracortical inhibition that is more prominent when assessed using the method of serial ascending order.

Significance: An integrated system for transcranial magnetic stimulation of the human motor system has been validated for clinical practice, suitable for the assessment of cortical function in neurological disease in an outpatient clinic setting.

Objective: In craniotomies requiring motor evoked potential (MEP) monitoring, avoiding neuromuscular blockade (NMB) is preferable, but its complete avoidance poses risks of unexpected movement. This retrospective study investigates the application of a post-tetanic MEP augmentation technique to enhance baseline recording of transcranial stimulation MEP (Tc-MEP) under partial NMB during craniotomy.

Methods: Twenty-six patients were included. The level of partial NMB was maintained at a train-of-four ratio of approximately 40 %. Monophasic constant-current stimulation was applied on the craniotomy side with + 20 % of the threshold intensity. Post-tetanic Tc-MEP, involving tetanic stimulation of the median nerve 1 s before transcranial stimulation, was performed on patients who failed to record using conventional baseline recording.

Results: The post-tetanic Tc-MEP technique successfully improved the success rate of baseline recording from 61.5 % to 100 %. Application of post-tetanic Tc-MEP significantly increased amplitudes in both the upper (p = 0.04) and lower limbs (p < 0.01) compared to before post-tetanic Tc-MEP. No patients had unexpected movements.

Conclusions: This study indicates that post-tetanic Tc-MEP enhanced the success rate of baseline recording during craniotomy under partial NMB.

Significance: The combination of partial NMB and post-tetanic Tc-MEP could be a useful regimen for craniotomy with MEP monitoring, addressing both safety concerns and successful baseline recording.