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1.

Objectives

Patients with chronic disorders of consciousness (DOC) may show alterations of autonomic function; however, in this clinical population, no data are available on the specific effects of nociceptive stimuli on cardiac autonomic control. Thus, we aimed at investigating the effects of a noxious stimulation on heart rate variability (HRV) in a population of patients with chronic DOC, taking into account different states of consciousness (vegetative state/unresponsive wakefulness syndrome, VS/UWS and minimally conscious state, MCS).

Methods

We enrolled twenty-four DOC patients (VS/UWS, n?=?12 and MCS, n?=?12). ECG and respiration were recorded during baseline, immediately after the nociceptive stimulus and, finally, during the recovery period. Linear and nonlinear HRV measures were used to evaluate the cardiac autonomic control.

Results

In DOC patients, nonlinear HRV analysis showed that nociceptive stimuli are able to elicit a change of autonomic function characterized by an increased sympathetic and a reduced vagal modulation. A significant reduction of autonomic complexity has also been detected. More interestingly, VS/UWS patients showed a less complex dynamics compared to MCS patients.

Conclusions

Cardiac autonomic responses are able to significantly differentiate the autonomic function between VS/UWS and MCS patients.

Significance

Nonlinear HRV analysis may represent a useful tool to characterize the cardiac autonomic responses to nociceptive stimuli in a chronic DOC population.  相似文献   

2.

Objective

We tested the feasibility of deploying a commercially available EEG-based brain-computer interface (BCI) in the intensive care unit (ICU) to detect consciousness in patients with acute disorders of consciousness (DoC) or locked-in syndrome (LIS).

Methods

Ten patients (9 DoC, 1 LIS) and 10 healthy subjects (HS) were enrolled. The BCI utilized oddball auditory evoked potentials, vibrotactile evoked potentials (VTP) and motor imagery (MoI) to assess consciousness. We recorded the assessment completion rate and the time required for assessment, and we calculated the sensitivity and specificity of each paradigm for detecting behavioral signs of consciousness.

Results

All 10 patients completed the assessment, 9 of whom required less than 1?h. The LIS patient reported fatigue before the end of the session. The HS and LIS patient showed more consistent BCI responses than DoC patients, but overall there was no association between BCI responses and behavioral signs of consciousness.

Conclusions

The system is feasible to deploy in the ICU and may confirm consciousness in acute LIS, but it was unreliable in acute DoC.

Significance

The accuracy of the paradigms for detecting consciousness must be improved and the duration of the protocol should be shortened before this commercially available BCI is ready for clinical implementation in the ICU in patients with acute DoC.  相似文献   

3.

Objective

Previous electrophysiological and psychophysical tests have suggested that somatosensory integration is abnormal in dystonia. Here, we hypothesised that this abnormality could relate to a more general deficit in pre-attentive error/deviant detection in patients with dystonia. We therefore tested patients with dystonia and healthy subjects using a mismatch negativity paradigm (MMN), where evoked potentials generated in response to a standard repeated stimulus are subtracted from the responses to a rare “odd ball” stimulus.

Methods

We assessed MMN for somatosensory and auditory stimuli in patients with cervical dystonia and healthy age matched controls.

Results

We found a significant group?1?oddball type interaction effect (F (1, 34)?=?4.5, p?=?0.04, ρI?=?0.63). A follow up independent t-test for sMMN data, showed a smaller sMMN amplitude in dystonic patients compared to controls (mean difference control-dystonia: ?1.0?µV ± 0.3, p?<?0.00, t?=??3.1). However the amplitude of aMMN did not differ between groups (mean difference control-dystonia: ?0.2?µV ± 0.2, p?=?0.24, t?=??1.2). We found a positive correlation between somatosensory MMN and somatosensory temporal discrimination threshold.

Conclusion

These results suggest that pre-attentive error/deviant detection, specifically in the somatosensory domain, is abnormal in dystonia. This could underlie some previously reported electrophysiological and psychophysical abnormalities of somatosensory integration in dystonia.

Significance

One could hypothesize a deficit in pre-conscious orientation towards potentially salient signals might lead to a more conservative threshold for decision-making in dystonia.  相似文献   

4.

Objectives

Brain-computer interfaces (BCIs) allow users to operate a device or application by means of cognitive activity. This technology will ultimately be used in real-world environments which include the presence of distractors. The purpose of the study was to determine the effect of visual distractors on BCI performance.

Methods

Sixteen able-bodied participants underwent neurofeedback training to achieve motor imagery-guided BCI control in an online paradigm using electroencephalography (EEG) to measure neural signals. Participants then completed two sessions of the motor imagery EEG-BCI protocol in the presence of infrequent, small visual distractors. BCI performance was determined based on classification accuracy.

Results

The presence of distractors was found to affect motor imagery-specific patterns in mu and beta power. However, the distractors did not significantly affect the BCI classification accuracy; across participants, the mean classification accuracy was 81.5?±?14% for non-distractor trials, and 78.3?±?17% for distractor trials.

Conclusion

This minimal consequence suggests that the BCI was robust to distractor effects, despite motor imagery-related brain activity being attenuated amid distractors.

Significance

A BCI system that mitigates distraction-related effects may improve the ease of its use and ultimately facilitate the effective translation of the technology from the lab to the home.  相似文献   

5.

Objective

The aim of this study was to evaluate how the motor unit number index (MUNIX) is related to the adapted multiple point stimulation (AMPS) technique.

Methods

MUNIX and AMPS technique were prospectively performed on thenar muscles in 20 consecutive patients referred to our neurophysiological laboratory with the clinical diagnosis of a possible motoneurone disorder (MND). The clinical and paraclinical assessment confirmed the diagnosis of MND in 13 out of 20 patients, amyotrophic lateral sclerosis (ALS) in 9 (with MND group). In the other 7 patients, there were neither evidence of MND, nor of any peripheral nervous system disease (without MND group).

Results

AMPS and MUNIX data were significantly (p?<?0.001) lower in patients with MND than in patients without MND. There was a strong significant positive linear correlation between AMPS and MUNIX values (n?=?20; R?=?0.83; p?<?0.01).

Conclusion

Both MUNIX and AMPS methods could serve as a reliable marker to document the motor unit loss.

Significance

The present paper constitutes one more clue of MUNIX reliability.  相似文献   

6.

Objective

Although it is believed that patients with Unresponsive Wakefulness Syndrome (UWS) do not feel pain, recent neuroimaging and neurophysiologic studies have demonstrated some residual traces of nociceptive processing.

Methods

To confirm this growing evidence, we evaluated 21 patients suffering from chronic disorders of consciousness (DOC) (both UWS, n = 11, and Minimally Conscious State – MCS –, n = 10), using an Event-Related Potential (ERP) Low-Resolution Brain Electromagnetic Tomography (LORETA) approach, based on nociceptive repeated laser stimulation (RLS). We delivered laser stimuli to the dorsum of both hands and analysed the γ-band LORETA activations and the ERP γ-power magnitude induced by laser stimulation, as well as the heart rate variability (HRV).

Results

We found partially preserved cortical activations and ERP γ-power magnitude in all MCS and two UWS individuals. These effects were paralleled by a purposeful behaviour, and a reduced HRV concerning nociceptive stimulation, whereas the two UWS individuals showed no more than reflex behaviours, besides a strong limbic activation.

Conclusions

Some UWS patients may somehow perceive the affective components of nociceptive stimulation.

Significance

The diagnosis of functional locked-in syndrome should be taken into account when dealing with DOC differential diagnosis.  相似文献   

7.

Objective

To assess the specificity of cortical inhibitory deficits in cervical dystonia patients.

Methods

A systematic test battery was developed to assess spatial and temporal aspects of cortical inhibition, in motor and somatosensory systems of the hand. We tested 17 cervical dystonia (CD) patients and 19 controls assessing somatosensory spatial inhibition (grating orientation test, interdigital feedforward subliminal inhibition), somatosensory temporal inhibition (temporal discrimination threshold, feedforward subliminal inhibition), motor spatial inhibition (surround inhibition), and motor temporal inhibition (short interval intracortical inhibition).

Results

A significant deficit in CD was observed in both measures of somatosensory spatial inhibition, with a trend in the same direction in our measure of motor spatial inhibition. We found no significant group differences in temporal inhibition measures. Importantly, statistical comparison of effect sizes across the different measures showed that deficits in tests of spatial inhibition were greater than those in tests of temporal inhibition.

Conclusion

Our results suggest that CD is associated with abnormal function of local inhibitory cortical circuits subserving spatial sensory processing. Importantly, this abnormality relates to the somatotopic representation of an unaffected body part.

Significance

These results clarify the nature of deficits in cortical inhibitory function in dystonia.  相似文献   

8.

Objective

Electrical median nerve somatosensory stimulation leads to a distinct modulation of cortical oscillations. Initial high frequency and gamma augmentation, as well as modulation of beta and alpha oscillations have been reported. We aimed at investigating the involvement of the subthalamic nucleus in somatosensory processing by means of local field potential recordings, since recordings during passive movements and peripheral somatosensory stimulation have suggested a prominent role.

Methods

Recordings of subthalamic neuronal activity following median nerve stimulation in 11 Parkinson’s disease patients were performed. Time-frequency analysis from 1 to 500?Hz was averaged and analyzed.

Results

Several oscillatory components in response to somatosensory stimulation were revealed in the time-frequency analysis: (I) prolonged increase in alpha band power, followed by attenuation; (II) initial suppression of power followed by a subsequent rebound in the beta band; (III) early broad-frequency increase in gamma band power; (IV) and sustained increase of 160?Hz frequency oscillations throughout the trial.

Conclusions

These results further corroborate the involvement of the subthalamic nucleus in somatosensory processing.

Significance

The present results not only support the notion of somatosensory processing in the subthalamic nucleus. Moreover, an improvement of somatosensory processing during subthalamic deep brain stimulation in Parkinson’s disease might be accounted for by enhancement of prevailing high frequency oscillations.  相似文献   

9.
10.

Objectives

Spinal Cord Injured (SCI) persons with and without Central Neuropathic Pain (CNP) show different oscillatory brain activities during imagination of movement. This study investigates whether they also show differences in movement related cortical potentials (MRCP).

Methods

SCI paraplegic patients with no CNP (n?=?8), with CNP in their lower limbs (n?=?8), and healthy control subjects (n?=?10) took part in the study. EEG clustering involved independent component analysis, equivalent current dipole fitting, and Measure Projection to define cortical domains that have functional modularity during the motor imagery task.

Results

Three domains were identified: limbic system, sensory-motor cortex and visual cortex. The MRCP difference between the groups of SCI with and without CNP was reflected in a domain located in the limbic system, while the difference between SCI patients and control subjects was in the sensorimotor domain. Differences in MRCP morphology between patients and healthy controls were visible for both paralysed and non paralysed limbs.

Conclusion

SCI but not CNP affects the movement preparation, and both SCI and CNP affect sensory processes.

Significance

Rehabilitation strategies of SCI patients based on MRCP should take into account the presence of CNP.  相似文献   

11.

Objective

We assessed sleep patterns in 85 patients with chronic disorders of consciousness (DOC) in order to reveal any relationship with the degree of the impairment.

Methods

Nocturnal polysomnography (PSG) was scored in patients classified as being in an unresponsive wakefulness syndrome/vegetative state (UWS/VS; n?=?49) or a minimally conscious state (MCS; n?=?36) in accordance with the rules of the American Academy of Sleep Medicine. The PSG data in the two diagnostic groups were compared, and the PSG parameters associated with the degree of impairment were analysed.

Results

In 19/49 UWS/VS patients, signal attenuation was the only EEG pattern detectable in sleep. Non-REM 2 (NREM2) and slow-wave sleep (SWS) (but not REM) stages were more frequent in the MCS patients. The presence of SWS was the most appropriate factor for classifying patients as UWS/VS or MCS, and the duration of SWS was the main factor that significantly correlated with revised Coma Recovery Scale scores.

Conclusion

The presence of NREM sleep (namely SWS) reflects better preservation of the circuitry and structures needed to sustain this stage of sleep in DOC patients.

Significance

PSG is a simple and effective technique, and sleep patterns may reflect the degree of impairment in chronic DOC patients.  相似文献   

12.

Objective

To investigate whether changes in the somatosensory temporal discrimination threshold (STDT) in Parkinson’s disease (PD) and dystonia reflect the involvement of specific neural structures or mechanisms related to tremor, and whether the STDT can discriminate patients with PD, dystonia or essential tremor (ET).

Methods

We tested STDT in 223 patients with PD, dystonia and ET and compared STDT values in patients with PD and dystonia with tremor with those of PD and CD without tremor. Data were compared with those of age-matched healthy subjects.

Results

STDT values were high in patients with dystonia and PD but normal in ET. In PD, STDT values were similar in patients with resting or postural/action tremor and in those without tremor. In dystonia, STDT values were higher in patients with tremor than in those without tremor. The ROC curve showed that STDT discriminates tremor in dystonia from ET.

Conclusions

In PD, STDT changes likely reflect basal ganglia abnormalities and are unrelated to tremor mechanisms. In dystonia, the primary somatosensory cortex and cerebellum play an additional role.

Significance

STDT provides information on the pathophysiological mechanisms of patients with movement disorders and may be used to differentiate patients with dystonia and tremor from those with tremor due to ET.  相似文献   

13.

Objective

The somatosensory temporal discrimination threshold (STDT), defined as the shortest time interval required for two tactile stimuli to be perceived as separate, is longer in patients with Parkinson’s disease (PD). In this review, we discuss STDT findings in healthy subjects and in PD patients and the relationship between altered STDT and motor disturbances.

Methods

A search was conducted on PubMed for papers dealing with PD and temporal discrimination published from January 1990 to July 2017.

Results

Abnormal STDT in PD correlates with disease duration, disease severity and degree of nigrostriatal dopamine loss, and responds to dopaminergic medication. In PD, a prolonged STDT does not correlate, or only marginally correlates, with clinically assessed bradykinesia of finger tapping. By contrast, a prolonged STDT correlates with the variability in amplitude and speed of finger tapping as assessed by means of neurophysiological techniques and may contribute to impaired finger dexterity in PD.

Conclusions

We suggest that abnormal temporal processing of sensory information in PD generates incorrect signals for the execution and control of voluntary movements.

Significance

This review sheds light on unsolved questions regarding the relationship between STDT alterations and motor disturbances in PD and proposes directions for future research on this topic.  相似文献   

14.

Objective

Current Brain-Computer Interface (BCI) systems typically flash an array of items from grey to white (GW). The objective of this study was to evaluate BCI performance using uniquely colored stimuli.

Methods

In addition to the GW stimuli, the current study tested two types of color stimuli (grey to color [GC] and color intensification [CI]). The main hypotheses were that in a checkboard paradigm, unique color stimuli will: (1) increase BCI performance over the standard GW paradigm; (2) elicit larger event-related potentials (ERPs); and, (3) improve offline performance with an electrode selection algorithm (i.e., Jumpwise).

Results

Online results (n = 36) showed that GC provides higher accuracy and information transfer rate than the CI and GW conditions. Waveform analysis showed that GC produced higher amplitude ERPs than CI and GW. Information transfer rate was improved by the Jumpwise-selected channel locations in all conditions.

Conclusions

Unique color stimuli (GC) improved BCI performance and enhanced ERPs. Jumpwise-selected electrode locations improved offline performance.

Significance

These results show that in a checkerboard paradigm, unique color stimuli increase BCI performance, are preferred by participants, and are important to the design of end-user applications; thus, could lead to an increase in end-user performance and acceptance of BCI technology.  相似文献   

15.

Objective

The aim of the paper is to objectively demonstrate that amputees implanted with intraneural interfaces are truly able to feel a sensation in the phantom hand by recording “phantom” somatosensory evoked potentials from the corresponding brain areas.

Methods

We implanted four transverse intrafascicular multichannel electrodes, available with percutaneous connections to a multichannel electrical stimulator, in the median and ulnar nerves of two left trans-radial amputees. Two channels of the implants that were able to elicit sensations during intraneural nerve stimulation were chosen, in both patients, for recording somatosensory evoked potentials.

Results

We recorded reproducible evoked responses by stimulating the median and the ulnar nerves in both cases. Latencies were in accordance with the arrival of somatosensory information to the primary somatosensory cortex.

Conclusion

Our results provide evidence that sensations generated by intraneural stimulation are truly perceived by amputees and located in the phantom hand. Moreover, our results strongly suggest that sensations perceived in different parts of the phantom hand result in different evoked responses.

Significance

Somatosensory evoked potentials obtained by selective intraneural electrical stimulation in amputee patients are a useful tool to provide an objective demonstration of somatosensory feedback in new generation bidirectional prostheses.  相似文献   

16.

Objectives

To evaluate whether the task-specific neural coupling mechanism during the performance of cooperative hand movements is preserved in tetraplegic subjects.

Methods

Recordings of ipsilateral and contralateral electromyographic reflex responses in activated forearm muscles and bilateral somatosensory potentials (SSEP) to unilateral ulnar nerve stimulations during rest, cooperative and non-cooperative hand movements.

Results

Contralateral reflex responses were present in almost all patients during cooperative hand movements but small in amplitude when hand function was severely impaired. Ipsilateral SSEP potentials were enhanced during both cooperative and, in contrast to healthy subjects, also non-cooperative bimanual movements.

Conclusions

Both results indicate a strong involvement of ipsilateral non-damaged cervical tracts and hemispheres in the control of bimanual hand movements in tetraplegic subjects.

Significance

This study on the neural control of bimanual movements in patients suffering a cervical injury allows designing therapeutic approaches for the improvement of hand function that are based on physiological insights.  相似文献   

17.

Objective

Sudoscan provides a rapid assessment of sudomotor function based on the measurement of electrochemical skin conductance (ESC), which is thought to be proportional to small nerve fibres innervating the sweat glands. However, the relationship between ESC and small nerve fibre density on skin biopsy remains unclear.

Methods

In a retrospective single-centre study, we compared ESC measurements with autonomic sweat gland nerve fibre density (SGNFD) and somatic intraepidermal nerve fibre density (IENFD) in patients with polyneuropathy.

Results

63 patients were included (mean age: 60.6?±?13.3?years). ESC was more strongly correlated with SGNFD (r?=?0.49; p?=?0.0005) than with IENFD (r?=?0.42; p?=?0.0005). Foot ESC was lower in patients with abnormal SGNFD (1.0?±?0.3 µS/kg versus 0.7?±?0.4 µS/kg; p?=?0.0419) or abnormal IENFD (1.1?±?0.3 µS/kg versus 0.8?±?0.3 µS/kg; p?=?0.0425).

Conclusion

ESC measurement is a novel method of potential value for assessing sudomotor function. More studies are required to define its place beside ancient well-established techniques.

Significance

The weak correlation of ESC with skin biopsy results suggests that mechanisms other than the loss of innervating fibres may be responsible for sweat gland dysfunction in polyneuropathies.  相似文献   

18.

Objectives

To report Somatosensory Evoked Potentials (SEPs) and Central Motor Conduction Times (CMCT) in children with dystonia and to test the hypothesis that these parameters predict outcome from Deep Brain Stimulation (DBS).

Methods

180 children with dystonia underwent assessment for Globus pallidus internus (GPi) DBS, mean age 10?years (range 2.5–19). CMCT to each limb was calculated using Transcranial Magnetic Stimulation. Median and posterior tibial nerve SEPs were recorded over contralateral and midline centro-parietal scalp. Structural abnormalities were assessed with cranial MRI. One-year outcome from DBS was assessed as percentage improvement in Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS-m).

Results

Abnormal CMCTs and SEPs were found in 19% and 47% of children respectively and were observed more frequently in secondary than primary dystonia. Of children proceeding to DBS, better outcome was seen in those with normal (n?=?78/89) versus abnormal CMCT (n?=?11/89) (p?=?0.002) and those with normal (n?=?35/51) versus abnormal SEPs (n?=?16/51) (p?=?0.001). These relationships were independent of dystonia aetiology and cranial MRI findings.

Conclusions

CMCTs and SEPs provide objective evidence of motor and sensory pathway dysfunction in children with dystonia and relate to DBS outcome.

Significance

CMCTs and SEPs can contribute to patient selection and counselling of families about potential benefit from neuromodulation for dystonia.  相似文献   

19.

Objective

To investigate the association between the frequency and intensity of fasciculations with clinical measures of disease progression in amyotrophic lateral sclerosis (ALS).

Methods

Twenty-four consecutive patients with ALS underwent clinical review and neuromuscular ultrasound assessment to detect intensity of fasciculations. Results were correlated with clinical markers of disease severity, as measured by the ALS Functional Rating Scale-revised (ALSFRS-R) and rate of disease progression (ΔFS), in addition to assessment of cortical motor function.

Results

Disease duration negatively correlated (R?=??0.530, p?<?0.01) with fasciculation intensity, while the ΔFS positively correlated with the fasciculation number (R?=?0.626, p?<?0.01). In terms of potential central contributions to ectopic impulse generation, patients were classified into cohorts based on their fasciculation intensity and short interval intracortical inhibition (SICI). ΔFS was significantly higher in patients with established hyperexcitability (low SICI) with high fasciculation intensity compared to those patients with minimal SICI change.

Conclusions

Fasciculation intensity appears linked to disease progression and separately to markers of cortical dysfunction, specifically the advent of cortical hyperexcitability.

Significance

Assessment of the intensity of patient fasciculations is a noninvasive approach that may provide further insight disease pathophysiology in ALS.  相似文献   

20.

Objectives

The present aging study investigated the impact of a multisession anodal-tDCS protocol applied over the primary motor cortex (M1) during motor sequence learning on generalization of motor learning and plasticity-dependent measures of cortical excitability.

Methods

A total of 32 cognitively-intact aging participants performed five consecutive daily 20-min sessions of the serial-reaction time task (SRTT) concomitant with either anodal (n?=?16) or sham (n?=?16) tDCS over M1. Before and after the intervention, all participants performed the Purdue Pegboard Test (PPT) and Transcranial Magnetic Stimulation (TMS) measures of cortical excitability were collected.

Results

Relative to sham, participants assigned to the anodal-tDCS intervention revealed significantly greater performance gains on both the trained SRTT and the untrained PPT as well as a greater disinhibition of long-interval cortical inhibition (LICI). Generalization effects of anodal-tDCS significantly correlated with LICI disinhibition.

Conclusion

Anodal-tDCS facilitates motor learning generalisation in an aging population through intracortical disinhibition effects.

Significance

The current findings demonstrate the potential clinical utility of a multisession anodal-tDCS over M1 protocol as an adjuvant to motor training in alleviating age-associated motor function decline. This study also reveals the pertinence of implementing brain stimulation techniques to modulate age-associated intracortical inhibition changes in order to facilitate motor function gains.  相似文献   

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