Showing papers in "Neurophysiologie Clinique-clinical Neurophysiology in 2022"
TL;DR: In this article , the drift diffusion model (DDM) was used to evaluate the impact of tDCS on cognitive performance via DDM measures, such as non-decision time, bias for decision, and speed of information processing.
Abstract: Performance accuracy and reaction time in cognitive tasks are routinely used to evaluate the efficacy of tDCS to affect cognitive task performance. tDCS alters the excitability of targeted brain areas and thereby alters performance of cognitive tasks. The drift diffusion model (DDM) provides some additional measures to explore information processing style, such as (non)decision time, bias for decision, and speed of information processing. DDM parameters are informative for the study of cognitive impairments in children with ADHD. In the present study, we aimed to evaluate the impact of tDCS on cognitive performance via DDM measures.This study conducted DDM modeling and reanalysis of two exploratory, single-blinded, within-subject design experiments, which were published earlier. In the first experiment, twenty- four children with ADHD performed a Go/ No- Go task during anodal or sham tDCS over the right dlPFC. In the second experiment, twenty- five children with ADHD performed the 1- back working memory task during anodal or sham tDCS over the left dlPFC. We reanalyzed the data after DDM modeling.The conventional performance measures revealed no significant effect of tDCS on No- Go accuracy in the first experiment and 1-back accuracy in the second experiment. The 1-back reaction time and speed-accuracy tradeoff were however improved under the real stimulation condition. The DDM measures identified increased No-Go- bias and decision time with respect to inhibitory control, and an increased threshold and amount of information required for response in the 1- back test.In children with ADHD, anodal tDCS over the right dlPFC induces more conservative and less impulsive decisions. Furthermore, anodal tDCS over the left dlPFC enhanced efficacy of working memory performance with respect to agility and capacity. The experimental results show that drift diffusion modeling is useful for evaluation of the impact of tDCS on the style of information processing.
7 citations
TL;DR: In this article , the inter-rater reliability of MScanFit MUNE using a "Round Robin" research design was assessed using the measures of Limits of Agreement (LOA) and Coefficient of Variation (COV).
Abstract: To assess the inter-rater reliability of MScanFit MUNE using a "Round Robin" research design.Twelve raters from different centres examined six healthy study participants over two days. Median, ulnar and common peroneal nerves were stimulated, and compound muscle action potential (CMAP)-scans were recorded from abductor pollicis brevis (APB), abductor digiti minimi (ADM) and anterior tibial (TA) muscles respectively. From this we calculated the Motor Unit Number Estimation (MUNE) and "A50", a motor unit size parameter. As statistical analysis we used the measures Limits of Agreement (LOA) and Coefficient of Variation (COV). Study participants scored their perception of pain from the examinations on a rating scale from 0 (no pain) to 10 (unbearable pain).Before this study, 41.6% of the raters had performed MScanFit less than five times. The mean MUNE-values were: 99.6 (APB), 131.4 (ADM) and 126.2 (TA), with LOA: 19.5 (APB), 29.8 (ADM) and 20.7 (TA), and COV: 13.4 (APB), 6.3 (ADM) and 5.6 (TA). MUNE-values correlated to CMAP max amplitudes (R2-values were: 0.463 (APB) (p<0.001), 0.421 (ADM) (p<0.001) and 0.645 (TA) (p<0.001)). The average perception of pain was 4.MScanFit indicates a high level of inter-rater reliability, even with only limited rater experience and is overall reasonably well tolerated by patients. These results may indicate MScanFit as a reliable MUNE method with potential as a biomarker in drug trials.
6 citations
TL;DR: In this article , a literature search identified 22 original experiments that explored the effects of transcranial direct current stimulation (tDCS) on attention bias in health and disease with different parameters and conditions, but the contribution of these factors to the magnitude and directionality of effects has not been comprehensively reviewed.
Abstract: Attention bias is a tendency to preferably detect, orient and select emotionally valued stimuli, as compared to neutral stimuli, and plays a crucial role in the psychopathology of various psychiatric disorders. Transcranial direct current stimulation (tDCS) has been applied for the alteration of attention bias in health and disease with different parameters and conditions, but the contribution of these factors to the magnitude and directionality of effects has not previously been comprehensively reviewed. In this review, we aimed to systematically explore the effects of tDCS on attention bias in different tasks, tDCS conditions, and health states. Data were collected in accordance with the PRISMA approach. A literature search identified 22 original experiments that explored the effects of tDCS on attention bias. Determinants of tDCS effects on attention bias were cortical target areas, the specific task under study, stimulation parameters, and the presence of psychopathology. Relevant cortical areas for modification of attention bias via tDCS were the dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC). The observed heterogeneity of the impact of tDCS on the modulation of attention bias can be explained by the area of stimulation, valence of stimuli, task characteristics, and the intensity of stimulation.
5 citations
TL;DR: In this paper , the effects of bifrontal tDCS on subjective and objective sleep measures were evaluated in patients with multiple sclerosis (PwMS) using the Epworth Sleepiness Scale (ESS) and actigraphy.
Abstract: Sleep complaints are commonly reported by patients with multiple sclerosis (PwMS). Several pharmacological and alternative interventions have been tried, but are usually faced by limited efficacy. Hence, exploring other methods such as transcranial direct current stimulation (tDCS), might be of interest. The aim of this study was to assess the effects of bifrontal tDCS on subjective (i.e., Epworth Sleepiness Scale (ESS)) and objective sleep measures (i.e., actigraphy).Seven patients completed the study. Patients randomly received two blocks of five daily sessions each in a crossover design (active and sham, with a washout interval of three weeks). The anode and cathode were placed over the left and right dorsolateral prefrontal cortices, respectively. Sleep assessment included ESS, sleep onset latency, total sleep duration, time in bed, sleep efficiency, waking after sleep onset, and number of awakenings.Compared to baseline scores (11.14 ± 4.06), significant decrease in ESS was obtained after active intervention (7.86 ± 4.18; p = 0.011), but not after sham intervention (9.57 ± 5.62; p = 0.142). No significant changes were observed with regards to actigraphy measures. Sessions were well tolerated, and no serious side-effects were reported at any time.Bifrontal tDCS resulted in significant improvement in daytime sleepiness, but did not yield any effect on objective sleep measures in PwMS. This discrepency might be explained by the modest association that could exist between objective and subjective sleep measures. In addition, it could be assumed that modulating objective sleep measures would require a larger sample size, more stimulation sessions, or modulation of other cortical areas.
5 citations
TL;DR: A systematic literature search of PubMed, Web of Science, Cochrane Library, VHL, EMBASE, PsycINFO, OVID, and CINAHL databases was carried out on articles published until July 2021 as discussed by the authors .
Abstract: To evaluate the effect of tDCS on tinnitus distress, loudness and psychiatric symptoms.A systematic literature search of PubMed, Web of Science, Cochrane Library, VHL, EMBASE, PsycINFO, OVID, and CINAHL databases was carried out on articles published until July 2021. Inclusion criteria were published controlled trials using tDCS intervention with tinnitus patients, using a sham/control group, and measuring tinnitus loudness, distress and/or psychiatric symptoms. A meta-analysis was performed for the overall effect as well as to compare subgroups according to tDCS target (left temporoparietal area (LTA) and dorsolateral prefrontal cortex (DLPFC)).Fourteen articles with 1031 participants were included. Six studies applied tDCS over the DLPFC, six over the LTA and two over both areas. Although the overall meta-analysis showed that tDCS significantly decreased tinnitus loudness (SMD=-0.35; 95%CI=-0.62 to -0.08, p = 0.01) and distress (SMD=-0.50, 95%CI=-0.91 to -0.10, p = 0.02).The subgroup analysis showed a significant effect only for tDCS over LTA for loudness (SMD=-0.46, 95%CI=-0.80 to -0.12, p = 0.009), and no other area resulted in significant change. There was no significant effect of treatment on psychiatric symptoms.tDCS may improve tinnitus loudness and distress with a small to moderate effect size. Despite the overall positive effect, only LTA tDCS yielded a significant effect. Further well-controlled studies with larger sample sizes and broader exploration of tDCS montages and doses are warranted.
5 citations
TL;DR: The posterior superior insula (PSI) has been shown to be a safe and potentially effective target for neuromodulation in peripheral neuropathic pain (PNP) in humans and animal models as discussed by the authors .
Abstract: The posterior-superior insula (PSI) has been shown to be a safe and potentially effective target for neuromodulation in peripheral neuropathic pain (PNP) in humans and animal models. However, it remains unknown whether there is a measurable responder profile to PSI stimulation. Two factors were hypothesized to influence the response of repetitive transcranial magnetic stimulation (rTMS) of the PSI: differences in rTMS target (discrete subregions of the PSI) or PNP phenotype.This is a secondary analysis from a randomized, double-blind, sham-controlled, cross-over trial assessing PSI-rTMS in PNP (N = 31, 5 days rTMS) (10.1016/j.neucli.2021.06.003). Active PSI-rTMS true responders (>50% pain reduction from baseline after active but not after sham series of treatment) were compared with not true responders, to determine whether they differed with respect to 1) rTMS neuro-navigational target coordinates, and/or 2) specific neuropathic pain symptom inventory (NPSI) clusters (pinpointed pain, evoked pain, and deep pain) at baseline.Mean rTMS target coordinates did not differ between true (n = 45.1%) and not true responders (p = 0.436 for X, p = 0.120 for Y, and p = 0.116 for Z). The Euclidian distance between true and not true responders was 4.04 mm. When comparing differences in responders between NPSI clusters, no participant within the evoked pain cluster was a true responder (p = 0.024).Response to PSI-rTMS may depend on pain cluster subtype rather than on differences in targeting within the PSI.
4 citations
TL;DR: In this paper , the authors used high density electroencephalography (hd-EEG) to identify markers of Parkinson's disease (PD) related anxiety, using 108 patients participated in the study and were divided into two groups: with and without clinically relevant anxiety, according to their score on the Parkinson Anxiety Scale.
Abstract: To identify markers of Parkinson's disease (PD) related anxiety, using high density electroencephalography (hd-EEG).108 patients participated in the study. They were divided into two groups: with and without clinically relevant anxiety, according to their score on the Parkinson Anxiety Scale. Resting-state hd-EEG was recorded. Spectral and functional connectivity characteristics were compared between the two groups.Thirty-three patients (31%) had significant anxiety symptoms. In the spectral analysis, relative power in the alpha1 frequency band in the right prefrontal cortex was lower in patients with anxiety than without. Functional connectivity analysis showed a stronger connectivity between the left insula and several regions of the right prefrontal cortex in patients with anxiety than in those without.This study shows the pivotal role of the insula and frontal cortex in the pathophysiology of anxiety in PD and extends the results of previous studies using magnetic resonance imaging or positron emission tomography imaging.
4 citations
TL;DR: In this article , the effects of multisite anodal transcranial direct current stimulation (tDCS) combined with cognitive stimulation (CS) over 2 months on cognitive performance and brain activity, and the relationship between them, in patients with Alzheimer's disease (AD) were examined.
Abstract: We aimed to examine the effects of multisite anodal transcranial direct current stimulation (tDCS) combined with cognitive stimulation (CS) over 2 months on cognitive performance and brain activity, and the relationship between them, in patients with Alzheimer's disease (AD).Patients with AD were randomly assigned to an active tDCS+CS (n=18) or a sham tDCS+CS (n=18) group. Cognitive performance was assessed using the Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-cog) and brain activity using EEG (spectral power and coherence analysis) before and after the intervention. Multisite anodal tDCS (2 mA, 30 min) was applied over six brain regions [left and right dorsolateral prefrontal cortex (F3 and F4), Broca's area (F5), Wernicke's area (CP5), left and right somatosensory association cortex (P3 and P4)] for 24 sessions (three times a week). Both groups performed CS during tDCS.Anodal tDCS+CS delays cognitive decline (ADAS-cog change) to a greater extent than sham tDCS+CS (-3.4±1.1 vs. -1.7±0.4; p=.03). Bilateral EEG coherence at high and low frequencies was greater for the active tDCS+CS than sham+CS group for most electrode pairs assessed (p < .05). The post-intervention ADAS-cog change score was predictive for EEG coherence at different sites (R²=.59 to .68; p < .05) in the active but not in the sham tDCS+CS group.Anodal tDCS+CS improved overall cognitive function and changed EEG brain activity compared to sham tDCS+CS. Changes in cognitive performance were associated with changes in EEG measures of brain activity. Anodal tDCS+CS appears to be a promising therapeutic strategy to modulate cortical activity and improve cognitive function in patients with AD.
4 citations
TL;DR: In this article , the authors compared autonomic function in Parkinson's disease (PD) associated with the leucine-rich repeat kinase (LRRK2) G2019S mutation and non-LRB2-PD, by the study of heart rate variability (HRV) and sympathetic skin responses (SSR).
Abstract: We aimed to assess and compare autonomic function in Parkinson's disease (PD) associated with the leucine-rich repeat kinase (LRRK2) G2019S mutation (LRRK2-PD) and non-LRRK2 PD, by the study of heart rate variability (HRV) and sympathetic skin responses (SSR).In a cross-sectional three-year study, fifty LRRK2-PD and fifty clinically matched non-LRRK2 PD patients were included. Cardiac parasympathetic functions were assessed using heart rate variation to deep breathing (HR-DB), to the Valsalva maneuver (HR-V) and to standing (HR-S) and the sympathetic autonomic system by sympathetic skin responses (SSR).Neurophysiological, parasympathetic and sympathetic dysautonomia were found in 78%, 69% and 37% of all PD patients respectively. Rates of dysautonomia in the LRRK2-PD and non-LRRK2 PD patient subgroups were 76% vs 80% (p = 0.405) for neurophysiological, 62% vs 76% (p = 0.123) for parasympathetic and 38% vs 36% (p = 0.500) for sympathetic dysautonomia. HR-S was the most frequently altered parameter in both groups, and was significantly associated with the tremor-dominant (TD) motor phenotype of PD in the total cohort (p = 0.004) and in LRRK2-PD (p = 0.015). In LRRK2-PD patients, female gender was associated with parasympathetic dysfunction (p = 0.024), and with altered HR-DB (p = 0.022). Early-onset parkinsonism was also significantly associated with preserved neurophysiological autonomic functions (p = 0.044) in LRRK2-PD. In non-LRRK2 PD patients, male gender was associated with early parasympathetic (p = 0.043) and sympathetic dysfunction (p = 0.007).Our study showed a roughly similar neurophysiological autonomic profile in non-LRRK2 PD and LRRK2-PD. The latter had some peculiarities with more marked parasympathetic dysfunction and more altered HR-DB in females, more altered HR-S in the TD-motor phenotype, and preserved autonomic functions in early-onset parkinsonism. These preliminary findings would require further investigations on larger genetically homogeneous cohorts to explore the multiple facets of autonomic dysfunction in PD.
3 citations
TL;DR: In this article , the effect of kinesiophobia and pain catastrophizing on pain-induced corticomotor modulation was assessed with the slopes of recruitment curves measured from the first dorsal interosseous elicited by transcranial magnetic stimulation before and during pain induced by capsaicin application on the forearm.
Abstract: Several studies suggest that acute pain decreases corticomotor excitability. However, the variability between patients remains important and unexplained. The aim of this study was to unveil potential sources of variation by looking at the effect of kinesiophobia and pain catastrophizing on pain-induced corticomotor modulation.Corticomotor excitability was assessed with the slopes of recruitment curves measured from the first dorsal interosseous elicited by transcranial magnetic stimulation before and during pain induced by capsaicin application on the forearm. Participants completed the Tampa Scale for Kinesiophobia (TSK) and the Pain Catastrophizing Scale (PCS).Twenty-four persons participated in the study. There was a moderate and positive correlation between individual changes in the slope of the recruitment curves and TSK questionnaire scores (rs=0.47; p = 0.02). During the painful condition, unlike those with higher TSK scores, participants with lower TSK scores demonstrated recruitment curves with reduced slopes compared to baseline. There was a difference between changes in the slopes of recruitment curves between individuals with "highest" vs. "lowest" kinesiophobia scores (p = 0.01). No relationship was observed between changes in the slopes of the recruitment curves and PCS scores (p = 0.20).The results suggest that kinesiophobia may affect neuromotor processes and influence the corticomotor pain response.Higher kinesiophobia scores during experimental induced pain were associated with smaller decreases in the slopes of recruitment curves. These findings suggest that there is less inhibition of corticospinal excitability in participants with greater TKS scores.
2 citations
TL;DR: In this article , the global effect of two high-frequency protocols of electric-field navigated repetitive transcranial magnetic stimulation (rTMS) targeted to functional facial motor cortex and comparing their efficacy and tolerability in patients with chronic facial pain was conducted.
Abstract: We conducted an open-label cross-over study assessing the global effect of two high-frequency protocols of electric-field navigated repetitive transcranial magnetic stimulation (rTMS) targeted to functional facial motor cortex and comparing their efficacy and tolerability in patients with chronic facial pain. Outcome predictors were also assessed.We randomized twenty consecutive patients with chronic facial pain (post-traumatic trigeminal neuropathic pain, n=14; persistent idiopathic facial pain, n=4; secondary trigeminal neuralgia, n=2) to receive two distinct 5-day rTMS interventions (10Hz, 2400 pulses and 20Hz, 3600 pulses) separated by six weeks. The target area was assessed by mapping of lower face representation. The primary endpoint was the change in weekly mean of pain intensity (numeric rating scale, NRS) between the baseline and therapy week (1st week), and follow-up weeks (2nd and 3rd weeks) for each rTMS intervention. Response was defined using a combination scale including the patient's global impression of change and continuance with maintenance treatment.Overall, pain intensity NRS decreased from 7.4 at baseline to 5.9 ten weeks later, after the second rTMS intervention (p=0.009). The repetition of the treatment had a significant effect (F=4.983, p=0.043) indicating that the NRS scores are lower during the second four weeks period. Eight (40%) patients were responders, 4 (20%) exhibited a modest effect, 4 (20%) displayed no effect, and 4 (20%) experienced worsening of pain. High disability and high pain intensity (>7) predicted a better outcome (p=0.043 and p=0.045). Female gender, shorter duration of pain and low Beck Anxiety Inventory scores showed a trend towards a better outcome (p=0.052, 0.060 and 0.055, respectively).High-frequency rTMS targeted to face M1 alleviates treatment resistant chronic facial pain. Repeated treatment improves the analgesic effect. A protocol with higher frequency (above 10Hz), longer session duration (more than 20 minutes) and higher number of pulses (above 2400 pulses/session) did not improve the outcome. The results support early consideration of rTMS.
TL;DR: In this article , the authors used intraoperative neurophysiological monitoring (IONM) in predicting immediate and 3-month postoperative neurological new deficit (or deterioration) in patients benefiting from spinal cord (SC) surgery; and to identify factors associated with a higher risk of postoperative clinical worsening.
Abstract: To assess the accuracy of intraoperative neurophysiological monitoring (IONM) in predicting immediate and 3-month postoperative neurological new deficit (or deterioration) in patients benefiting from spinal cord (SC) surgery; and to identify factors associated with a higher risk of postoperative clinical worsening.Consecutive patients who underwent SC surgery with IONM were included. Pre and postoperative clinical (modified McCormick scale), radiological (lesion-occupying area ratio), and electrophysiological features were collected.A total of 99 patients were included: 14 (14.1%) underwent extradural surgery, 50 (50.5%) intradural extramedullary surgery, and 35 (35.4%) intramedullary surgery. Cumulatively, multimodal IONM (motor and somatosensory evoked potentials, D-wave whenever possible) significantly predicted postoperative deficits (p<0.001), with a sensitivity, specificity, positive predictive value, and negative predictive value of 0.81, 0.93, 0.83, and 0.92, respectively. Sixty (60.6%) patients displayed no IONM change, whereas 39 (39.4%) displayed IONM worsening. In multivariate analysis, predictors for postoperative clinical worsening were: abnormal preoperative electrophysiological assessment (p=0.03), intramedullary tumor (p<0.001), lesion-occupying area ratio ≥0.7 (p<0.001), and IONM alterations (p<0.001). Three months after the surgical procedure, in patients presenting at least one of the risk factors described above, 45/81 (55.6%) and 19/81 (23.5%) were clinically and electrophysiologically improved, respectively; while 13/81 (16.0%) and 10/81 (12.3%) were clinically and electrophysiologically worsened.Multimodal IONM is an essential tool to guide SC surgery, and enables the accurate prediction of postoperative neurological outcome. Specific attention should be given to patients presenting with preoperative electrophysiological abnormalities, large tumor volume, and intramedullary tumor location.
TL;DR: In this paper , the authors investigated differences in beat-to-beat systolic blood pressure variability (SBPV) in people with secondary progressive MS, clinically isolated syndrome (pwCIS) and healthy controls (HC).
Abstract: To investigate differences in beat-to-beat systolic blood pressure variability (SBPV) in people with secondary progressive MS (pwSPMS), clinically isolated syndrome (pwCIS) and healthy controls (HC). This retrospective case-control study included 46 pwSPMS, 46 pwCIS and 44 HC. A semi-automated software made with MATLAB R2019b (The MathWorks, Inc.) was used for the evaluation of SBPV. The frequency domain characteristics observed were the power spectrum in the LF and HF bands and the LF/HF ratio. Data is expressed in absolute power (mmHg2) of LF and HF and ratio (LF/HF) during both supine and tilt-up phases of testing. There were no significant differences in mean systolic (sBP) or diastolic blood pressure (dBP) values during supine and tilt-up phases of testing between groups. During the supine phase of testing LF and LF/HF were significantly lower in the SPMS group (4.17±5.38 and 3.52±2.34, respectively) compared to the CIS (5.42±3.59, p = 0.015 and 5.92±4.63, p = 0.029, respectively) and HC group (6.03±4.55, p = 0.011 and 6.52 ± 5.09, p = 0.010, respectively), while during the tilt-up phase, LF was significantly lower compared to both the CIS and HC group, and HF was significantly lower only compared to the CIS group. SBPV is altered in pwSPMS compared to pwCIS and normal controls. Further research in the field of MS related dysautonomia is warranted not only because of its relevance to comorbidities and MS symptoms, but also because of its likely involvement in the pathophysiology of MS.
TL;DR: A global regularity score is proposed, easily derived from visual EEG inspection, that may be a reliable prognostic tool for patients with post-anoxic coma and is strongly associated with poor outcome.
TL;DR: The authors compared the effect of age and cerebellar transcranial direct current stimulation (CRB-tDCS) on motor learning in two different manual dexterity tasks, visuomotor force control vs. effector selection (independent finger movements).
Abstract: The role of the cerebellum in motor learning of dexterous control and interaction with aging remains incompletely understood. We compared the effect of age and cerebellar transcranial direct current stimulation (CRB-tDCS) on motor learning in two different manual dexterity tasks, visuomotor force control vs. effector selection (independent finger movements).Twenty younger and 20 older adults were randomized (double-blinded) to anodal or sham CRB-tDCS during dexterity training over three consecutive days, and followed-up at day 10. Motor learning was measured as (i) overall learning (across 10 days), (ii) within-day (short-term) learning, (iii) between-day learning (consolidation), and (iv) retention (long-term learning; day 3 to day 10).Younger and older subjects showed significant overall learning in both tasks. Subjects with poor initial performance showed stronger learning. No effects of CRB-tDCS were observed in younger adults. A significant Age*CRB-tDCS interaction showed that CRB-tDCS improved within-day learning in finger independence (improved reaction time in effector selection) in older adults. However, a significant Age*CRB-tDCS interaction showed that CRB-tDCS impacted consolidation negatively in older subjects. No stimulation effects were found on retention. Finally, we found that degree of within-day learning in finger independence (change in reaction times) correlated with baseline (pre-training) reaction times in both young and old subjects.The results suggest that CRB-tDCS may improve short-term learning of manual dexterity in older adults in a task-dependent manner, specifically in difficult tasks requiring effector (action) selection. However, cerebellar tDCS stimulation may also interfere with consolidation in older subjects. These results need confirmation in a larger sample.
TL;DR: In this paper , the authors investigated the impact of exercise and high frequency repetitive nerve stimulation (RNS) following changes induced by 75 min of immobility, and found that RNS had no effect and cycling exercise reduced H-reflex latencies and decreased homosynaptic depression at 2 Hz.
Abstract: The excitability of lower motor neurons can be explored non-invasively by several neurophysiological techniques, e.g., F-wave and H-reflex studies after a period of immobility and then after subsequent exercise. The aim of this study is to investigate the impact of exercise and high frequency repetitive nerve stimulation (RNS) following changes induced by 75 min of immobility.We studied 10 healthy subjects following 75 min lower limb immobility, then randomized to RNS or cycling on different days. The neurophysiological studies of M-response, F-wave latency, F/M amplitude ratio and persistence; H-reflex threshold and latency, H/M amplitude ratio, and homosynaptic depression were performed at baseline, after immobility and immediately following the intervention, using stimulation of posterior tibial and peroneal nerves.After immobility F-wave latencies were delayed and homosynaptic depression at 2 Hz was increased (p < 0.025). RNS had no effect, but cycling exercise reduced H-reflex latencies (p = 0.025) and decreased homosynaptic depression at 2 Hz.Our findings suggest that both proprioceptive stimulation and supraspinal pathways modulate intraspinal physiological changes after immobility. These observations suggest that specific exercise protocols may be useful in managing patients recovering from periods of immobility.
TL;DR: In this article , an electrophysiological marker of proprioceptive spino-cortical tracts integrity based on corticokinematic coherence (CKC) was developed in young children with unilateral cerebral palsy (UCP), in which behavioral measures are not applicable.
Abstract: To develop an electrophysiological marker of proprioceptive spino-cortical tracts integrity based on corticokinematic coherence (CKC) in young children with unilateral cerebral palsy (UCP), in whom behavioral measures are not applicable.Electroencephalography (EEG) signals from 12 children with UCP aged 19 to 57 months were recorded using 128-channel EEG caps while their fingers were moved at 2 Hz by an experimenter, in separate sessions for the affected and non-affected hands. The coherence between movement kinematics and EEG signals (i.e., CKC) was computed at the sensor and source (using a realistic head model) levels. Peaks of CKC obtained for the affected and non-affected hands were compared for location and strength. The relation between CKC strength on the lesion-side, the lesion-type (cortico-subcortical vs. subcortical) and the level of manual ability were studied with 2-way repeated-measures ANOVA.At the individual level, a significant CKC peak at the central area contralateral to the moved hand was found in all young children with their non-affected hand and in 8 out of 12 children with their affected hand. At the group level, CKC to the affected hand movements was weaker than CKC to the non-affected hand movements. This difference was influenced by the type of lesion, the effect being predominant in the subgroup (n = 5) with cortico-subcortical lesions.CKC is measurable with EEG in young children with UCP and provides electrophysiological evidence for altered proprioceptive spino-cortical tracts on the lesioned brain hemisphere, particularly in children with cortico-subcortical lesions.
TL;DR: In this article , a multimodal intraoperative neurophysiologic monitoring (IONM) protocol is used for stratifying patients according to the risk of spinal cord ischemia at the end of the vascular phase of surgery.
Abstract: Despite the introduction of several adjuncts to improve spinal perfusion, spinal cord ischemia (SCI) remains a devastating complication of thoracoabdominal aortic aneurysm (TAAA) repair. Our aim was to assess the effects on clinical outcome of interventions triggered by motor evoked potentials (MEP) alerts. Furthermore, we want to assess whether a multimodal intraoperative neurophysiologic monitoring (IONM) protocol is helpful for stratifying patients according to the risk of SCI at the end of the vascular phase of surgery.We prospectively studied one-hundred consecutive patients who underwent TAAA repair. We applied a multimodal IONM including MEP, somatosensory evoked potentials (SEP) and peripheral nerve monitoring techniques. Signal deteriorations were classified as reversible/irreversible according to whether they recovered or not at the end of monitoring (EOM), set at the end of the vascular phase of surgery. Significant MEP changes drove a series of corrective measures aimed to improve spinal perfusion.The rate of immediate postoperative motor deficits consistent with SCI was significantly higher with irreversible MEP deteriorations compared to reversible ones. The interpretation of MEP findings at the EOM led to the development of risk categories for SCI, based on the association between MEP results and motor outcome.Our data seem to justify interventions made to reverse MEP deterioration in order to improve the clinical outcome. A multimodal IONM protocol could improve MEP interpretation at the end of the vascular phase of surgery, supporting the surgeon in their decision-making, before concluding vascular maneuvers.
TL;DR: In this paper , a randomized crossover study was conducted on 22 patients with major depression and 21 healthy volunteers who received 20 min of active and sham 40 Hz gamma tACS over bilateral dorsolateral prefrontal cortex during a computerized n-back task in a cross-over design.
Abstract: Gamma transcranial alternating current stimulation (gamma tACS) is considered a non-invasive brain stimulation technique for modulation of cognitive performance and for treatment of psychiatric disorders. There is heterogeneous data on its effectiveness in improving working memory.In this randomized crossover study, we tested 22 patients with major depression and 21 healthy volunteers who received 20 min of active and sham 40 Hz gamma tACS over bilateral dorsolateral prefrontal cortex during a computerized n-back task in a cross-over design.We showed no improvement in reaction time and accuracy of working memory during active or sham stimulation in both groups, and no interaction between cognitive load and stimulation conditions.The present study suggests that a single session of gamma tACS does not affect cognition in depression. However, the bilateral electrode montage and learning or ceiling effects may have affected results. Overall, this study is in line with the heterogeneous results of previous gamma tACS studies, emphasizing that methodologies and study designs should be harmonized.
TL;DR: In this paper , the effects of one versus two daily sessions of anodal transcranial direct current stimulation (a-tDCS) delivered to the left dorsolateral prefrontal cortex (DLPFC) for 10 days in a cohort of 30 women with chronic migraine (CM, disease duration: 37.8±48.41 month).
Abstract: We compared the effects of one versus two daily sessions of anodal transcranial direct current stimulation (a-tDCS) delivered to the left dorsolateral prefrontal cortex (DLPFC) for 10 days in a cohort of 30 women (mean age 28.0±6.92) with chronic migraine (CM, disease duration: 37.8±48.41 month). Participants were randomly allocated to three groups: a-tDCS 1-s Group received one daily a-tDCS session; a-tDCS 2-s Group received two daily a-tDCS sessions; Group SHAM received one daily session with a simulated (placebo) current. All participants were assessed before, after and one month after treatment, using the Migraine Disability Assessment, Montreal Cognitive Assessment, d2 Test of Attention, Trail Making Test (part B), Sequence of Letters and Numbers of the Wechsler Adult Intelligence Scale – III, and Nine Hole Peg Test. We found no difference between groups in the cognitive measures and motor dexterity. However, after treatment, a significant decrease in migraine-related disability was found for the a-tDCS 1-s Group. For all variables, no cumulative effects were observed in a-tDCS 2-s compared to the a-tDCS 1-s Group. The study findings provide preliminary results for future clinical trials designed to compare different intervals between tDCS sessions in CM.
TL;DR: In this article , the authors evaluate the resulting value of jitter measured from a simulated examination recording and analyze its dependence on both the number of SFPs contributing either to the triggering peak or the non-triggered peak, and time shifting (delays of triggering at the end-plate) of individual SFP in these paired potentials.
Abstract: The aim of this simulation study was to evaluate the resulting value of jitter measured from a simulated examination recording and to analyze its dependence on both the number of SFPs contributing either to the triggering peak or the non-triggered peak, and time shifting (delays of triggering at the end-plate) of individual SFPs in these paired potentials.We simulated potentials recorded using a concentric needle electrode with two well separated peaks, and performed a simulated examination (consisting of 50 trains of 100 discharges) with an assumed number of fibers forming peaks. For each train, fiber diameters were chosen at random within the allowed ranges. For each discharge the delay of triggering for each fiber at the end-plate was selected at random from an assumed range. The mean jitter values were calculated, together with the median and 95% quantile.The results suggest that jitter is related to the mean of the individual SFP shifts.These findings extend the understanding of reduced jitter measurements using a concentric needle electrode. If more than one fiber forms the peak, then jitter decreases due to averaging of individual time shifts of potentials constituting the peak, rather than due to detection of the SFP with the earliest peak.
TL;DR: In this article , clinical and neurophysiological predictors of motor event-related desynchronization (ERD) and synchronization (ERS) in patients with chronic pain due to knee osteoarthritis (KOA) were examined.
Abstract: The study aimed to examine the clinical and neurophysiological predictors of motor event-related desynchronization (ERD) and synchronization (ERS) in patients with chronic pain due to knee osteoarthritis (KOA). We performed a cross-sectional analysis of our cohort study (DEFINE cohort), KOA arm, with 71 patients, including demographic, functionality, genetic and neurophysiological measures. ERD/ERS was evaluated during hand motor tasks (motor execution, active and passive observation, and imagery). Multivariate regression models were used to explore predictors of ERD/ERS. Although we found an altered ERD/ERS pattern during motor execution and active observation, the ERS pattern could only be clearly differentiated after passive observation.`. We found no predictors of ERD (excitatory biomarker). For ERS (inhibitory biomarker), our results showed that the main predictors differ across EEG frequency bands. Considering pain measures, we found that visual analogue scale (VAS, right knee) and chronicity of pain negatively predict low beta and high beta ERS, respectively. Pain threshold was positively correlated with alpha ERS, while 36-Item Short Form Survey (SF-36) emotional domain positively predicted beta ERS. Regarding transcranial magnetic stimulation (TMS) markers, intracortical inhibition (ICF) negatively predicted beta and low beta ERS, and left hemisphere cortical silent period (CSP) negatively predicted low beta ERS. Considering that higher power of ERS indicates a stronger cortical organization and inhibitory drive, our results show that limitation of activities due to emotional factors, lower pain threshold, higher VAS pain, and longer duration of pain are associated with lower ERS power (in alpha and beta frequencies), thus indicating a lower inhibitory drive. In the same direction, a lower inhibitory drive as indicated by higher ERS power is associated with higher ICF amplitude. Although there was a negative association between ERS and CSP, this may indicate that ICF values are adjusting CSP results. Our findings support the idea that a less organized cortical response as indicated by changes to the ERS is associated with higher pain correlates in subjects with KOA.
TL;DR: In this article , the authors investigated the predictors of clinical outcomes in unresponsive patients with acquired brain injuries and found that mismatch negativity (MMN) amplitude at electrode Fz (FzMMNA; p < 0.001), EEG pattern (p = 0.015), sleep spindles (p= 0.018), EEG reactivity (EEG-R), p <0.001) and P3a latency (P3a) were significantly correlated with patient prognosis, with an area under the receiver operating characteristic curve (AUC) of 0.884.
Abstract: To investigate the predictors of clinical outcomes in unresponsive patients with acquired brain injuries.Patients with coma or disorders of consciousness were enrolled from August 2019 to March 2021. A retrospective analysis of demographics, etiology, clinical score, diagnosis, electroencephalography (EEG), and event-related potential (ERP) data from 1 week to 2 months after coma onset was conducted. Findings were assessed for predicting favorable outcomes at 6 months post-coma, and functional outcomes were determined using the Glasgow Outcome Scale-Extended (GOS-E).Of 68 patients, 22 patients had a good neurological outcome at 6 months, while 11 died. Univariate analysis showed that motor response (Motor-R; p < 0.001), EEG pattern (p = 0.015), sleep spindles (p = 0.018), EEG reactivity (EEG-R; p < 0.001), mismatch negativity (MMN) amplitude at electrode Fz (FzMMNA; p = 0.001), P3a latency (p = 0.044), and P3a amplitude at electrode Cz (CzP3aA; p < 0.001) were significantly correlated with patient prognosis. Multivariable logistic regression analysis showed that FzMMNA, CzP3aA, EEG-R, and Motor-R were significant independent predictors of a favorable outcome. The sensitivity and specificity of FzMMNA (dichotomized at 1.16 μV) were 86.4% and 58.5%, and of CzP3aA (cut-off value 2.76 μV) were 90.9% and 70.7%, respectively. ERP amplitude (ERP-A), a combination of FzMMNA and CzP3aA, improved prediction accuracy, with an area under the receiver operating characteristic curve (AUC) of 0.884. A model incorporating Motor-R, EEG-R, and ERP-A yielded an outstanding predictive performance (AUC=0.921) for a favorable outcome.ERP-A and the prognostic model resulted in the efficient prediction of a favorable outcome in unresponsive patients.
TL;DR: In this paper , the authors compared intra-epidermal electrical stimulation (IES) compared to contact heat stimulation in healthy controls, and explore the feasibility and potential added value of IES in the diagnosis of spinal disorders.
Abstract: To test the robustness and signal-to-noise ratio of pain-related evoked potentials following intra-epidermal electrical stimulation (IES) compared to contact heat stimulation in healthy controls, and to explore the feasibility and potential added value of IES in the diagnosis of spinal disorders.Pain-related evoked potentials induced by IES (custom-made, non-invasive, concentric triple pin electrode with steel pins protruding 1 mm from the anode, triangularly separated by 7-10 mm respectively) and contact heat stimulation were compared in 30 healthy subjects. Stimuli were applied to four different body sites. Two IES intensities, i.e., high (individually adapted to contact heat painfulness) and low (1.5 times pain threshold), were used. Additionally, a 40-year-old patient with unilateral dissociated sensory loss due to a multi-segmental syringohydromyelia was assessed comparing IES and contact heat stimulation.Both IES and contact heat stimulation led to robust pain-related evoked potentials recorded in all healthy subjects. Low intensity IES evoked potentials (14.1-38.0 µV) had similar amplitudes as contact heat evoked potentials (11.8-32.3 µV), while pain ratings on the numeric rating scale were lower for IES (0.8-2.5, compared to 1.5-3.9 for contact heat stimulation). High intensity IES led to evoked potentials with higher signal-to-noise ratio than low intensity IES and contact heat stimulation. The patient case showed impaired pain-related evoked potentials in segments with hypoalgesia for both IES modes. IES evoked potentials were preserved, with delayed latencies, while contact heat evoked potentials were abolished.IES evoked robust pain-related cortical potentials, while being less painful in healthy controls. The improved signal-to-noise ratio supports the use of IES for objective segmental testing of nociceptive processing. This was highlighted in a spinal syndrome case, where IES as well as contact heat stimulation reliably detected impaired segmental nociception.
TL;DR: In this paper , a study was conducted to differentiate individuals with early-onset Alzheimer's disease (EOAD) and identify differences of functional connectivity in resting-state EEG between individuals with EOAD and late onset AD (LOAD) in comparison with both healthy young and elderly individuals.
Abstract: The aim of this study was to differentiate individuals with early-onset Alzheimer's disease (EOAD) and identify differences of functional connectivity in resting-state EEG between individuals with EOAD and late-onset AD (LOAD) in comparison with both healthy young and elderly individuals.Forty EOAD and 56 LOAD patients were included along with 51 demographically matched young, and 54 elderly healthy individuals as controls to the EOAD and LOAD groups. Four minutes of resting-state EEG were recorded during the eyes-closed condition. The absolute value of imaginary coherence (ICoh) was measured for connectivity. The maximum values of ICoh were measured at delta (0.5-3.5 Hz), theta (4-7.5Hz), alpha (8-13 Hz), alpha-1 (8-10 Hz), alpha-2 (10.5-13 Hz), beta (13-30 Hz), beta-1 (13-20 Hz), and beta-2 (20.5-30 Hz) frequency bands.Individuals with EOAD showed higher coherence values in all frequency bands than LOAD patients. Compared to young healthy controls (YHC), EOAD had increased ICoh values in theta and beta-2 bands, whereas LOAD had lower ICoh values in the alpha-1 band than elderly healthy controls (EHC). Lastly, patients with EOAD demonstrated negative moderate correlations between language domains and beta-1 ICoh values.To the authors' knowledge, this is the first study evaluating coherence alterations among early-and late-onset AD patients and the diagnostic value of coherence measures. It was suggested that EOAD patients had more severe pathological changes compared with LOAD.
TL;DR: In this article , a parallel threshold-tracking SICI protocol, with 6 stimuli per inter-stimulus interval (ISI), was proposed to reduce time and stimulus numbers by 40% without appreciable loss of accuracy.
Abstract: Reduced short-interval intracortical inhibition (SICI) in motor neuron disease has been demonstrated by amplitude changes (A-SICI) and threshold-tracking (T-SICI) using 10 stimuli per inter-stimulus interval (ISI). To test whether fewer stimuli would suffice, A-SICI and T-SICI were recorded twice from 30 healthy subjects using 6 and 10 stimuli per ISI. Using fewer stimuli increased mean A-SICI variances by 23.8% but the 7.3% increase in T-SICI variance was not significant. We conclude that our new parallel threshold-tracking SICI protocol, with 6 stimuli per ISI, can reduce time and stimulus numbers by 40% without appreciable loss of accuracy.
TL;DR: In this paper , the effect of common transcranial magnetic stimulation (TMS) waveforms (monophasic and biphasic) on resting motor threshold, active motor threshold (RMT), and motor evoked potential (MEP) amplitudes in the biceps and first dorsal interosseous (FDI) was determined.
Abstract: The purpose of this study was to determine the effect of common transcranial magnetic stimulation (TMS) waveforms (monophasic and biphasic) on resting motor threshold (RMT), active motor threshold (AMT), and motor evoked potential (MEP) amplitudes in the biceps and first dorsal interosseous (FDI) because waveforms may affect motor targets differently. We also determined test-retest reliability. Ten individuals participated in two sessions of TMS delivered to the motor cortex. Monophasic stimulation to induce a posterior–anterior current in the brain (monoPA) and biphasic posterior–anterior then anterior-posterior (biPA-AP) were applied in each session in random order. In each session, there were four blocks of measurements (2 muscles × 2 waveforms) of RMT, AMT and MEPs at the hotspot location. MEPs were normalized to the maximum EMG signal. RMTs and AMTs were lower for monoPA compared to biPA-AP stimulation for the biceps (p<0.01) and FDI (p<0.01). Normalized MEPs were greater for monoPA compared to biPA-AP stimulation in the FDI (p=0.01) and not different in the biceps (p=0.86). Motor thresholds were not different between sessions suggesting high reliability (p<0.01). Normalized MEPs had very low reliability across sessions in the FDI, and moderate reliability in the biceps. Preliminary investigation suggests the effect of TMS waveform on motor thresholds is similar in upper limb proximal and distal muscles, but the effect differs per motor target for MEPs. Further, test–retest reliability of waveform effects was sensitive to target muscle. These findings may contribute to improve the efficacy and reliability of TMS for clinical use.
TL;DR: In this article , a stereological evaluation of autonomic fibers and sweat glands has been performed to identify structural evidence of denervation in patients with ALS, and the results showed that the degenerative process in autonomic nerve fibers is relatively slow compared to the rate of motor neuron degeneration in this condition.
Abstract: Previous studies have identified autonomic dysfunction in amyotrophic lateral sclerosis (ALS) using mostly neurophysiological techniques. In this study, stereological evaluation of autonomic fibers and sweat glands has been performed to identify structural evidence of autonomic denervation in patients with ALS. In this study, 29 ALS patients were compared to 29 controls using COMPASS-31 questionnaire, sympathetic skin response (SSR), and heart rate variability (HRV) at rest. From the same cohorts, 20 ALS patients and 15 controls were further evaluated using staining of autonomic nerve fibers and sweat glands in skin biopsies. SSR and resting HRV were repeated in the ALS patient cohort one year later. COMPASS-31 total score, gastrointestinal- and urinary-sub scores were higher in ALS patients than controls (P = 0.004, P = 0.005, and P = 0.049, respectively). In the ALS patient cohort, SSR amplitudes in hands and feet were lower than in controls (P<0.0001 and P = 0.0009, respectively), but there was no difference in resting HRV (P>0.05). While there was no change in nerve fibers innervating sweat glands, their density was lower in ALS patients than controls, and semi-quantitative analysis also showed structural damage (P = 0.02 and P = 0.001, respectively). SSR and resting HRV of ALS patients remained stable during the one-year follow-up period (P>0.05). Supporting abnormal neurophysiological tests, stereological analysis revealed direct evidence of autonomic denervation in ALS patients. However, the degenerative process in autonomic nerve fibers is relatively slow, compared to the rate of motor neuron degeneration in this condition.