Short-latency Somatosensory Evoked Potentials Research Articles

A case of autoimmune glial fibrillary acidic protein astrocytopathy with excessive startle response and cortical hyperexcitability

AbstractWe herein report a 60‐year‐old man with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP‐A) with excessive startle response (ESR), or hyperekplexia. Short‐latency somatosensory evoked potentials (SSEPs) revealed high‐amplitude potentials of the early cortical component. Anti‐GFAPα antibodies in the spinal fluid were positive. The hyperekplexia, other clinical symptoms, and SSEP abnormalities were resolved by corticosteroid therapy. The present case demonstrates that ESR can be associated with GFAP‐A, and its pathophysiology may be cortical hyperexcitability.

Promoting the process of determining brain death through standardized training.

This study aims to explore the training mode for brain death determination to ensure the quality of subsequent brain death determination. A four-skill and four-step (FFT) training model was adopted, which included a clinical neurological examination, an electroencephalogram (EEG) examination, a short-latency somatosensory evoked potential (SLSEP) examination, and a transcranial Doppler (TCD) examination. Each skill is divided into four steps: multimedia theory teaching, bedside demonstration, one-on-one real or dummy simulation training, and assessment. The authors analyzed the training results of 1,577 professional and technical personnel who participated in the FFT training model from 2013 to 2020 (25 sessions), including error rate analysis of the written examination, knowledge gap analysis, and influencing factors analysis. The total error rates for all four written examination topics were < 5%, at 4.13% for SLSEP, 4.11% for EEG, 3.71% for TCD, and 3.65% for clinical evaluation. The knowledge gap analysis of the four-skill test papers suggested that the trainees had different knowledge gaps. Based on the univariate analysis and the multiple linear regression analysis, among the six factors, specialty categories, professional and technical titles, and hospital level were the independent influencing factors of answer errors (p < 0.01). The FFT model is suitable for brain death (BD) determination training in China; however, the authors should pay attention to the professional characteristics of participants, strengthen the knowledge gap training, and strive to narrow the difference in training quality.

Evoked potential response in patients with idiopathic Parkinson’s disease and atypical parkinsonian syndromes: A comparative study

Patients with idiopathic Parkinson&amp;rsquo;s disease (IPD) and atypical parkinsonian syndromes (APSs) suffer from a range of disorders, especially in balance and locomotion, which necessitate visual, auditory, and somatosensory inputs. In this study, IPD patients, APS patients, and healthy controls (HCs) (n = 50 per group) underwent a series of assessments for visual evoked potentials (VEP), brainstem auditory evoked response (BAER), and short-latency somatosensory evoked potentials (SSEP). Results showed that VEP P100 latency was prolonged in multiple system atrophy-cerebellar type (MSA-C), multiple system atrophy-parkinsonian type (MSA-P), and corticobasal ganglionic degeneration (CBD) patients. The latency of peaks III and V was prolonged in IPD, MSA-C, dementia with Lewy bodies (DLB), and Parkinson&amp;rsquo;s disease dementia (PDD). BAER I-III and I-V interpeak latency were prolonged in IPD, DLB, and PDD, whereas BAER I-III, III-V, and I-V interpeak latencies were increased and the V/I amplitude ratio was decreased in MSA-C. The central sensory conduction time (N20-N13) was increased in MSA-P and MSA-C in SSEP. IPD patients had prolonged VEP P100 latency (P &lt; 0.001), lower VEP N75-P100 amplitude (P &lt; 0.001), prolonged BAER I, II, II, IV, V peak latencies (P &lt; 0.001), I-III, I-V interpeak latencies (P &lt; 0.001), lower BAER V/I amplitude ratio (P &lt; 0.001), and prolonged SSEP N13, N20, central sensory conduction time (N20-N13) (P &lt; 0.001) than HCs. IPD patients also had prolonged BAER I, II, II, IV, V peak latencies (P &lt; 0.001), prolonged I-III, I-V interpeak latencies (P &lt; 0.001), and shorter SSEP N13, N20, central sensory conduction time (N20-N13) (P &lt; 0.001) than APS patients. Moreover, APS patients had prolonged VEP P100 and N145 latencies (P &lt; 0.001) and decreased N75-N145 amplitude (P &lt; 0.001) compared to HCs. APS patients also had prolonged BAER II, II, IV, V peak latencies (P &lt; 0.001), prolonged I-III, III-V, I-V interpeak latencies (P &lt; 0.001), decreased V/I amplitude ratio, and prolonged SSEP N13, N20, central sensory conduction time (N20-N13) (P &lt; 0.001) than HCs. Postural instability and gait disorder (PIGD) IPD had significantly prolonged BAER III, V peak latencies (P &lt; 0.05), and prolonged III-V interpeak latencies (P &lt; 0.05) compared to tremor-dominant IPD. Overall, the IPD and APS patients had significant VEP, BAER, and SSEP abnormalities of demyelination and axonal variety in the visual, auditory, and somatosensory pathways. The changes were also correlated with the disease duration and severity. Although the diseases are predominantly motor disorders with significant non-motor components, these electrophysiological abnormalities might open a new avenue to assess the non-motor symptoms.

Effect of guipizide maleate with hyperbaric oxygen therapy on neurophysiology and coagulation indices in patients with severe craniocerebral injury

Purpose: To assess the effect of guipizide maleate combined with hyperbaric oxygen therapy on neurophysiological and coagulation indices in patients with heavy craniocerebral injury.Methods: The study involved a total of 80 patients with craniocerebral injuries who were admitted to The 900th Hospital of China Joint Logistic Support Force, Fuzhou, China from January 2017 to June 2021. Patients were randomly divided into study group and a control group comprising 40 patients each. The study group received guipizidine maleate combined with hyperbaric oxygen therapy while control group received hyperbaric oxygen therapy. Differences in neurophysiological and coagulation indices were recorded for the two groups after treatment.Results: Short latency somatosensory evoked potential (SLSEP) N20 wave amplitude of the study group was significantly greater than that of control group (p &lt; 0.05). At 3 months follow-up, Glasgow outcome score (GOS), Karnofsky performance status (KPS) score, and Barthel index in the study group were significantly lower than in control group (p &lt; 0.05). The combined incidence of complications in the study group was 5 % (2/40), which was lower than in control group, 17.50 % (7/40)Conclusion: The combination of guipizide maleate with hyperbaric oxygen has good therapeutic effect on patients with severe craniocerebral injury. It significantly improves neuro-physiological and coagulation indices, reduces the incidence of complications during treatment, and improves neurological function. However, further clinical trials are required to validate these findings

The role of the electroencephalogram and evoked potentials after cardiac arrest.

In comatose cardiac arrest survivors, the electroencephalogram (EEG) is the most widely used test to assess the severity of hypoxic-ischemic brain injury (HIBI) and guide antiseizure treatment. However, a wide variety of EEG patterns are described in literature. Moreover, the value of postarrest seizure treatment is uncertain. Absent N20 waves of short-latency somatosensory-evoked potentials (SSEPs) are a specific predictor of irreversible HIBI. However, the prognostic significance of the N20 amplitude is less known. The increasing adoption of standardized EEG pattern classification identified suppression and burst-suppression as 'highly-malignant' EEG patterns, accurately predicting irreversible HIBI. Conversely, continuous normal-voltage EEG is a reliable predictor of recovery from postarrest coma. A recent trial on EEG-guided antiseizure treatment in HIBI was neutral but suggested potential benefits in specific subgroups. A prognostic approach based on the amplitude rather than on the presence/absence of the N20 SSEP wave recently showed greater sensitivity for poor outcome prediction and added potential for predicting recovery. Standardized EEG terminology and quantitative approach to SSEP are promising for improving the neuroprognostic accuracy of these tests. Further research is needed to identify the potential benefits of antiseizure treatment after cardiac arrest.

Sensorimotor integration and motor learning during a novel visuomotor tracing task in young adults with attention-deficit/hyperactivity disorder.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that has noted alterations to motor performance and coordination, potentially affecting learning processes and the acquisition of motor skills. This work will provide insight into the role of altered neural processing and sensorimotor integration (SMI) while learning a novel visuomotor task in young adults with ADHD. This work compared adults with ADHD (n = 12) to neurotypical controls (n = 16), using a novel visuomotor tracing task, where participants used their right-thumb to trace a sinusoidal waveform that varied in both frequency and amplitude. This learning paradigm was completed in pre, acquisition, and post blocks, where participants additionally returned and completed a retention and transfer test 24 h later. Right median nerve short latency somatosensory-evoked potentials (SEPs) were collected pre and post motor acquisition. Performance accuracy and variability improved at post and retention measures for both groups for both normalized (P < 0.001) and absolute (P < 0.001) performance scores. N18 SEP: increased in the ADHD group post motor learning and decreased in controls (P < 0.05). N20 SEP: increased in both groups post motor learning (P < 0.01). P25: increased in both groups post motor learning (P < 0.001). N24: increased for both groups at post measures (P < 0.05). N30: decreased in the ADHD group and increased in controls (P < 0.05). These findings suggest that there may be differences in cortico-cerebellar and prefrontal processing in response to novel visuomotor tasks in those with ADHD.NEW & NOTEWORTHY Alterations to somatosensory-evoked potentials (SEPs) were present in young adults with attention-deficit/hyperactivity disorder (ADHD), when compared with neurotypical controls. The N18 and N30 SEP peak had differential changes between groups, suggesting alterations to olivary-cerebellar-M1 processing and SMI in those with ADHD when acquiring a novel visuomotor tracing task. This suggests that short-latency SEPs may be a useful biomarker in the assessment of differential responses to motor acquisition in those with ADHD.

NIMG-100. THE MEDIAN NERVE STIMULATION INDUCES LONG LATENCY GAMMA MODULATIONS IN THE PRIMARY SOMATOSENSORY CORTEX, WHICH DIFFERENTIATES THE CONSCIOUS STATE

Abstract OBJECTIVE While the intraoperative assessment of the short-latency somatosensory evoked potentials (SSEPs) phase reversal in electrocorticogram (ECoG) is routinely used to locate the central sulcus (CS), its spatial-spectral patterns in the primary sensorimotor cortex and the relation to consciousness is not well characterized. Our goal was to evaluate the functional utility of using median nerve stimulation-induced ECoG sub-band modulations in pre-and post-CS to differentiate between anesthetized and awake states. Method: SSEPs were recorded from the sensorimotor cortex with ECoG during routine intraoperative cortical mapping of 8 patients in the anesthetized and awake states. We conducted a time-frequency analysis on the SSEP trace in each state to extract the spectral modulations up to 900Hz and contrasted their intensity in M1 and S1 to discern awake from anesthetized states. RESULTS We observed late gamma activity ranging from 60-250Hz, starting approximately 50ms after stimulation onset and extending up to 250ms. The late gamma activity was suppressed in the anesthetized state in both M1 (p&amp;lt; 0.01) and S1 (p=0.0369). Whiles in the awake state, the late gamma power increased significantly with respect to baseline both in M1 (p=0.0180) and S1 (p&amp;lt; 0.01). The difference in late gamma power between the anesthetized and the awake state was highly significant for M1 (p&amp;lt; 0.01) and for S1 (p&amp;lt; 0.01). CONCLUSION The results show that besides CS delineation, SSEPs long latency gamma modulations can serve as an additional biomarker to monitor the level of consciousness in neurosurgical practice.

Amplitude of Somatosensory Evoked Potentials (SEPs) Recorded in Short-Latency SEP Condition Is 80% of That in Giant SEP Condition.

Giant somatosensory evoked potentials (SEPs) with enhanced long-loop reflex (C-reflex) are useful to detect cortical motor hyperexcitability in patients with myoclonic epilepsy. The recording conditions of giant SEPs are different from those of short-latency SEPs (SSEPs). We investigated the waveform characteristics obtained for each condition. Forty-eight upper limbs of 24 adult normal subjects (12 men, age 35.5 ± 9.7 years [mean ± SD]) were investigated. Somatosensory evoked potentials of each subject were recorded in both conditions on the same day. The main differences in recording conditions were reference electrodes (SSEP: Fz vs. giant SEP: the earlobe electrode ipsilateral to the stimulated limb), stimulus rate (5 vs. 1 Hz), and bandpass filter (20 Hz-3 kHz vs. 1 Hz-1 kHz). Somatosensory evoked potentials were elicited by unilateral percutaneous electrical stimulation of the median nerve at the wrist with intensity of 110% of the movement threshold and recoded at C3'/C4'. The amplitudes of N20 onset-N20 and N20-P25 were significantly larger in giant SEP condition than in SSEP condition ( p < 0.001). The mean + 3SD of N20-P25 amplitude was 10.0 μV in giant SEP condition and 7.8 μV in SSEP condition. The N20-P25 amplitude was significantly correlated between giant SEP condition and SSEP condition ( R = 0.64, p < 0.001). C-reflex was not elicited. The amplitude of SEPs in SSEP condition is equivalent to 80% of that in giant SEP condition. The information is useful for detecting cortical hyperexcitability in various neurological disorders including myoclonic epilepsy.

Prediction of Cross-Clamp-Induced Cerebral Ischemia During Carotid Endarterectomy Using Arterial Blood Flow Assessment

BackgroundCross-clamping during carotid endarterectomy (CEA) is associated with the risk of cerebral ischemia. Various studies have evaluated different criteria for detecting cerebral ischemia, but difficulties arise when ischemic changes appear after the carotid artery is cross-clamped and incised. Here, we explored a parameter that can predict cerebral ischemia prior to cross-clamping during CEA using a blood-flow meter. MethodsThe carotid arterial blood flow was measured directly (direct ABF) in the common carotid artery prior to cross-clamping. The anatomical information in preoperative magnetic resonance imaging, cerebral blood flow in xenon-enhanced computed tomography, and carotid peak systolic flow velocity by carotid echo from the skin surface were also evaluated. A decrease in the short-latency somatosensory evoked potentials (SSEP) during cross-clamping to insert a shunt was assessed, and a decrease in amplitude of ≥ 50% was considered an indicator for cerebral ischemia. Surgery was performed under general anesthesia, and a shunt was inserted in all cases. ResultsOf 156 CEA patients between April 2013 and March 2020, 30 had decreased SSEP during cross-clamping. The baseline characteristics and intra- and postoperative findings were not significantly different between patients with and without a decrease in SSEP. Among the evaluated parameters, only the direct-ABF ratio (ABF-internal carotid artery/ABF-common carotid artery) differed significantly between the 2 groups (P = 0.011). The direct-ABF ratio ≤ 0.58 was predictive of cerebral ischemia during CEA. ConclusionsDirect-ABF measurement with an ultrasonic blood-flow meter can be useful for predicting cerebral ischemia prior to carotid artery cross-clamping during CEA.

Neural excitability and sensory input determine intensity perception with opposing directions in initial cortical responses.

Perception of sensory information is determined by stimulus features (e.g., intensity) and instantaneous neural states (e.g., excitability). Commonly, it is assumed that both are reflected similarly in evoked brain potentials, that is, larger amplitudes are associated with a stronger percept of a stimulus. We tested this assumption in a somatosensory discrimination task in humans, simultaneously assessing (i) single-trial excitatory post-synaptic currents inferred from short-latency somatosensory evoked potentials (SEPs), (ii) pre-stimulus alpha oscillations (8-13 Hz), and (iii) peripheral nerve measures. Fluctuations of neural excitability shaped the perceived stimulus intensity already during the very first cortical response (at ~20 ms) yet demonstrating opposite neural signatures as compared to the effect of presented stimulus intensity. We reconcile this discrepancy via a common framework based on the modulation of electro-chemical membrane gradients linking neural states and responses, which calls for reconsidering conventional interpretations of brain potential magnitudes in stimulus intensity encoding.

Unsupervised machine learning can delineate central sulcus by using the spatiotemporal characteristic of somatosensory evoked potentials

Objective. Somatosensory evoked potentials (SSEPs) recorded with electrocorticography (ECoG) for central sulcus (CS) identification is a widely accepted procedure in routine intraoperative neurophysiological monitoring. Clinical practices test the short-latency SSEPs for the phase reversal over strip electrodes. However, assessments based on waveform morphology are susceptible to variations in interpretations due to the hand area’s localized nature and usually require multiple electrode placements or electrode relocation. We investigated the feasibility of unsupervised delineation of the CS by using the spatiotemporal patterns of the SSEP captured with the ECoG grid. Approach. Intraoperatively, SSEPs were recorded from eight patients using ECoG grids placed over the sensorimotor cortex. Neurosurgeons blinded to the electrophysiology identified the sensory and motor gyri using neuronavigation based on sulcal anatomy. We quantified the most discriminatory time points in SSEPs temporal profile between the primary motor (M1) and somatosensory (S1) cortex using the Fisher discrimination criterion. We visualized the amplitude gradient of the SSEP over a 2D heat map to provide visual feedback for the delineation of the CS based on electrophysiology. Subsequently, we employed spectral clustering using the entire the SSEP waveform without selecting any time points and grouped ECoG channels in an unsupervised fashion. Main results. Consistently in all patients, two different time points provided almost equal discrimination between anterior and posterior channels, which vividly outlined the CS when we viewed the SSEP amplitude distribution as a spatial 2D heat map. The first discriminative time point was in proximity to the conventionally favored ∼20 ms peak (N20), and the second time point was slightly later than the markedly high ∼30 ms peak (P30). Still, the location of these time points varied noticeably across subjects. Unsupervised clustering approach separated the anterior and posterior channels with an accuracy of 96.3% based on the time derivative of the SSEP trace without the need for a subject-specific time point selection. In contrast, the raw trace resulted in an accuracy of 88.0%. Significance. We show that the unsupervised clustering of the SSEP trace assessed with subdural electrode grids can delineate the CS automatically with high precision, and the constructed heat maps can localize the motor cortex. We anticipate that the spatiotemporal patterns of SSEP fused with machine learning can serve as a useful tool to assist in surgical planning.

Electroencephalography and somatosensory evoked potentials in Covid-19 patients. Experience in recording and using telemedicine technologies to analyze results

A new coronavirus COVID-19 has led to the development of a global pandemic. It is characterized by a high risk of developing pneumonia and multiple organ failure along with its capability to influence the central nervous system. The main methods of instrumental assessment of the functional state of the brain are electroencephalography (EEG) and somatosensory evoked potentials (SEPs), which have been routinely used with patients in critical care units.We recorded the EEGs and short-latency SEPs of 31 COVID-19 patients, all were treated at the N. V. Sklifosovsky Research Institute of Emergency Care in 2020. The combined data was used to analyse the following outcome.We detected abnormal EEGs in 23 COVID-19 patients (74 %). Seven (30.4 %) patients showed EEGs consisting of diffuse non-specific slowing, 4 patients had lateralized hemispheric slowing (17.4 %) and one patient (4,3 %) had frontal intermittent delta activity (FIRDA). Three (13 %) patients in comas had “burst-suppression» pattern, three (13 %) had isoelectric EEGs and two (8,7 %) had areactive alpha rhythm, regarded as an electrographic manifestation of alpha coma. Two patients had evidence of epileptiform discharges (9 %), triphasic waves were presented in one patient (4.3 %).EEG and SEPs with the median nerve stimulation in COVID-19 patients do not reveal specific changes, nevertheless they are informative instrumental methods for assessing the functional state of the brain to identify biomarkers of epileptic seizures and to prognosticate survival and recovery in comatose patients.

Short-latency somatosensory-evoked potentials demonstrate cortical dysfunction in patients with Angelman syndrome.

BackgroundAngelman syndrome (AS) is neurodevelopmental disorder, causal gene of which is maternally expressed UBE3A. A majority of patients results from the large deletion of relevant chromosome which includes GABAA receptor subunit genes (GABARs) as well as UBE3A (AS Del). We previously reported aberrantly desynchronized primary somatosensory response in AS Del by using magnetoencephalography. The purpose of this study is to estimate cortical and subcortical involvement in the deficit of primary somatosensory processing in AS.MethodsWe analyzed short-latency somatosensory-evoked potentials (SSEPs) in 8 patients with AS Del. SSEPs were recorded on a 4-channel system comprising of two cortical electrodes which were placed on the frontal and centro-parietal areas. The peak and onset latency of each component were measured to compare latency and interval times.ResultsThe first-cortical peak latency (N20, P20), and N13-N20 peak interval times were significantly prolonged in AS Del compared to healthy controls. In contrast, there was no difference in latencies between subcortical components up to N20 onset or for N11-N20 onset interval times.ConclusionHighly desynchronized first-cortical SSEP components and normal latencies of subcortical components indicated cortical dysfunction rather than impairment of afferent pathways in AS Del patients, which might be attributed to GABAergic dysfunction due to loss of UBE3A function and heterozygosity of GABARs

Predicting the prognosis for severe brain injury patients: short-latency somatosensory evoked potential combined with electroencephalogram reactivity

Objective: To explore the the effectiveness of using short-latency somatosensory evoked potential(SLSEP) combined with electroencephalogram(EEG) reactivity to predict the prognosis of severe brain injury(SBI) patients. Methods: Consecutive patients with SBI admitted in neurosurgery intensive care unit(NSICU) at Xiangya Hospital of Central South University from July 2018 to January 2019 were prospectively collected. SLSEP and EEG were recorded in these patients in NSICU within two weeks after injury onset. EEG reactivity(EEG-R) was tested during EEG signal stabilization. In addition, the concentrations of serum neuron-specific enolase (NSE) and S100 protein were also detected. All patients were evaluated with Glasgow Outcome Scale(GOS) during 12 months' follow-up. GOS grade 3 to 5 was defined as favorable group, and GOS grade 1 to 2 was defined as unfavorable group. The association of relevant predictors with patient's prognosis was assessed. The area under the receiver operating characteristic (ROC) curve (AUC) was used to evaluate each potential predictor. Results: Forty-three patients were included in the study, with 26 patients of favorable outcomes and 17 patients with unfavorable prognosis. Univariate analysis revealed that the Glasgow Coma Scale (GCS) score, the concentration of serum NSE, EEG-R, the amplitude of SLSEP were all associated with the prognosis after 12 months' follow-up. Moreover, the AUC for prediction of favorable prognosis by GCS, NSE, EEG-R, SLSEP was 0.661(95%CI: 0.493-0.829), 0.697(95%CI: 0.531-0.862), 0.718(95%CI: 0.557-0.879) and 0.758(95%CI: 0.609-0.907) respectively. However, there was no significant difference of age, gender, pupillary light reflex and S100 protein between the two groups. Furthermore, multiple logistic regression analysis showed that only SLSEP amplitude (OR=2.058, 95%CI: 0.867-4.888) and EEG-R(OR=3.748, 95%CI: 0.857-16.394) were independent predictors of favorable prognosis, and the prognostic model containing these two variables yielded an predictive performance with an AUC of 0.798. Conclusion: The higher amplitude of SLSEP and the existence of EEG-R are predictors of good prognosis in SBI patients, and the combined use of SLSEP and EEG-R in predicting the prognosis of SBI patients is more reliable.

Neurophysiology and neuroimaging accurately predict poor neurological outcome within 24 hours after cardiac arrest: The ProNeCA prospective multicentre prognostication study

AimsTo investigate the ability of 30-min electroencephalogram (EEG), short-latency somatosensory evoked potentials (SEPs) and brain computed tomography (CT) to predict poor neurological outcome (persistent vegetative state or death) at 6 months in comatose survivors of cardiac arrest within 24 h from the event. MethodsProspective multicentre prognostication study in seven hospitals. SEPs were graded according to the presence and amplitude of their cortical responses, EEG patterns were classified according to the American Clinical Neurophysiology Society terminology and brain oedema on brain CT was measured as grey/white matter (GM/WM) density ratio. Sensitivity for poor outcome prediction at 100% specificity was calculated for the three tests individually and in combination. None of the patients underwent withdrawal of life-sustaining treatments before the index event occurred. ResultsA total of 346/396 patients were included in the analysis. At 6 months, 223(64%) had poor neurological outcome; of these, 68 were alive in PVS. Bilaterally absent/absent-pathological amplitude cortical SEP patterns, a GM/WM ratio<1.21 on brain CT and isoelectric/burst-suppression EEG patterns predicted poor outcome with 100% specificity and sensitivities of 57.4%, 48.8% and 34.5%, respectively. At least one of these unfavourable patterns was present in 166/223 patients (74.4% sensitivity). Two unfavourable patterns were simultaneously present in 111/223 patients (49.7% sensitivity), and three patterns in 38/223 patients (17% sensitivity). ConclusionsIn comatose resuscitated patients, a multimodal approach based on results of SEPs, EEG and brain CT accurately predicts poor neurological outcome at 6 months within the first 24 h after cardiac arrest.

P1-5-09. The effect of weight load added to thumb on short-latency somatosensory evoked potentials

This study examined the effects of unilateral and bilateral holding tasks with weight loads added to the thumbs on short-latency somatosensory evoked potentials (SSEP). Nine healthy volunteers participated in this study. The participants assumed a supine position with the forearms supinated. During palmar adduction, a 250 g weight was loaded onto the phalanx of the thumb. The holding tasks consisted of maintaining the joint angle of the thumb of the right hand, left hand, or bilateral hands. SSEP following right median nerve stimulation was recorded, and the amplitudes of N9, N13, N20, and N20-P25 components were analyzed. The amplitudes of N9 and N13 did not change during any tasks, whereas the amplitudes of N20 and N20-P25 were significantly lower in the task with right hand loaded. It is thought that the excitability of the motor-related area that activated with voluntary movement suppressed sensory input to the somatosensory area. These results suggest that the high excitability of the left motorrelated area that occurred with right hand movement suppressed the sensory input to the somatosensory area more than when bilateral hands were used.

Use of somatosensory evoked potentials for preoperative assessment in patients with severe aneurysmal subarachnoid hemorrhage before surgical or interventional treatment: a prospective observational cohort study

To explore the application value of short latency somatosensory evoked potentials (SLSEP) as a tool for preoperative assessment of surgical or interventional treatment in patients with severe aneurysmal subarachnoid hemorrhage (aSAH). A prospective observational cohort study was conducted. The patients with severe aSAH with a WFNS grade of IV or V admitted to intensive care unit (ICU) of Beijing Tiantan Hospital of Capital Medical University from November 2016 to April 2017 were enrolled. The patients received SLSEP monitoring within 12 hours after onset, and the monitoring results were classified according to the Judson scale. Meanwhile, the findings on cerebral CT scans at admission were evaluated by the modified Fisher classification. The follow-up was performed at 3 months after aSAH ictus based on the modified Rankin scale (mRS), and a mRS score 0-3 was defined as favorable outcome, 4-6 was defined as unfavorable outcome. For statistical evaluation, demographic, clinical, neuroimaging and SLSEP data were evaluated by univariate analysis to identify the risk factors associated with prognosis; afterwards, those factors were analyzed by multivariate Logistic regression; also the validity was assessed by calculating the respective sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). A total of 41 patients with aSAH were selected, of which 7 were excluded because of the interference of the SLSEP monitoring results, 34 patients with aSAH were enrolled finally. Among them, 21 were classified in the unfavorable outcome group, while the rest (n = 13) were allocated into the favorable outcome group. No significant difference was found in gender, age, body mass index (BMI), time delay from ictus to treatment or the options for therapeutic methods between the two groups. The findings of univariate analysis, however, showed statistically differences in WFNS grade, the modified Fisher scale and Judson scale of SLSEP between the two groups. Yet, the further validity evaluation for these predictors demonstrated that the sensitivity, specificity, PPV and NPV of WFNS grade of V and modified Fisher scale of IV were all less than 85%, whereas the results for SLSEP Judson scale of III were much better (sensitivity: 90.5% vs. 71.4% and 71.4%, specificity: 84.6% vs. 69.2% and 76.9%, PPV: 90.5% vs. 79.0% and 83.3%). In the following multivariate Logistic analysis, only Judson scale of III was identified to be the independent risk factor for poor outcome [odds ratio (OR) = 45.73, 95% confidence interval (95%CI) = 4.25-499.31, P = 0.002], while the WFNS grade of V (OR = 1.14, 95%CI = 0.12-13.06, P = 0.912) and the modified Fisher scale of IV (OR = 7.22, 95%CI = 0.51-113.20, P = 0.160) were merely associated with poor outcomes without significant independence. In comparison with WFNS grade and the modified Fisher scale, SLSEP seems more accurate in the prediction of long-term outcome of severe aSAH prior to surgical or interventional treatment, and thus may be applied as an effective aid in preoperative assessment.

The determination of brain death in coma children with Glasgow coma scale score 3

Objective To summarize the clinical features and technical key points on brain death during decision-made process in children with suspected brain death. Methods Twenty-four coma children with Glasgow coma scale score 3 and no spontaneous respiration were collected from May 2015 to February 2017 in Beijing Children′s Hospital, Capital Medical University to make the brain death determination.All children received at least one confirmatory test.According to the Chinese standards for determining brain death (pediatric), all patients were divided into brain death group and non-compliance group.The clinical features were analyzed.The sensitivity, specificity, false positive rate and false negative rate of electroencephalogram (EEG), short latency somatosensory evoked potential (SLSEP) and transcranial Doppler sonography (TCD) were calculated. Results Among these 24 cases, there were 16 males and 8 females, aged 5.6 (2.0, 8.8) years old.Ten cases met the criteria of brain death.Twelve (50%, 12/24 cases) cases received autonomic breathing test.A total of 25 tests were conducted, of which 21 were successful.The completion rates of EEG, TCD and SLSEP were 100.0% (24/24 cases), 83.3% (20/24 cases) and 54.2% (13/24 cases), respectively.EEG had the highest sensitivity (100%) and specificity (79%). SLSEP had good sensitivity (100%), but the specificity was only 40%.The combination of EEG with SLSEP had the highest specificity and sensitivity, both of which were 100%, and the false positive rate and false negative rate were 0. Conclusions The key to determine brain death successfully is to make adequate preparations, to receive formal training and to apply standard operation.In the determination of brain death in children, EEG has a good sensitivity and specificity in single confirmation test, which is the priority item.The combination of EEG with SLSEP is the most advantageous. Key words: Glasgow coma scale; Coma; Child; Brain death

The potential role of pain-related SSEPs in the early prognostication of long-term functional outcome in post-anoxic coma

Cardiac arrest (CA) is a common cause of disability. Multimodal evaluation has improved prognosis but precocious biomarkers are not appropriate in determining long-term functional outcome. To identify early prognostication markers of long-term functional outcome in post-anoxic coma. Retrospective assessment of outcomes. Individuals older than 18 years with post-anoxic coma hospitalized in intensive care units after cardiac arrest (CA) regardless of cause (cardiac or non-cardiac) and location of event (in or out-of-hospital). Clinical, biological and neurophysiological data were collected within 48 hours from CA. Clinical data included time of no and low flow, CA rhythm, pupillary reflex, Glasgow motor score at admission and hyperthermia. Biological marker was the highest creatinine level. Neurophysiological parameters included EEG pattern and reactivity, Somatosensory Evoked Potential (SSEP), and Middle-Latency (ML) SSEP evoked at low (10 mA) and high (50 mA) intensity stimulation. Level of Cognitive Functioning Scale (LCFS), Disability Rating Scale and recovery from coma (Revised coma Recovery Scale [CRS-R]) were collected at 12 months. A LASSO multiple regression analysis was fitted to data to investigate the best predictors of LCF, DRS and CRS-R. In-sample prediction was obtained to verify the quality of fitting, and accuracy indices (i.e., total error rate) produced. Presence of short and medium latency SSEPs with low and high stimulation intensity were identified as prognostic predictors of outcome for all the scales. Error rate was 4.5% for CRS and LCF, and 9.1% for DRS. Middle latency somatosensory evoked potentials associated with short latency somatosensory evoked potentials during the first 48 hours after a cardiac arrest are strong predictors of functional outcome at 12 months from the event. Replication on larger cohorts is needed to support their routine use as prognostic markers. These markers could inform more appropriate allocation of resources, provide a basis for realistic goal-setting, and help the family to adjust its expectations.

Short-Latency Somatosensory Evoked Potentials in Restless Leg Syndrome

Short-Latency Somatosensory Evoked Potentials in Restless Leg Syndrome