Absence Of Somatosensory Evoked Potentials Research Articles

Intra-operative Neurophysiological Monitoring in Patients Undergoing Posterior Spinal Correction Surgery with Pre-operative Neurological Deficit: Its Feasibility and High-risk Factors for Failed Monitoring.

Considering spinal deformity patients with pre-operative neurological deficit were associated with more intra-operative iatrogenic neurological complications than those without, intra-operative neurophysiological monitoring (IONM) has been used for detecting possible iatrogenic injury timely. However, the IONM waveforms are often unreliable. To analyze the performance of intra-operative neurophysiological monitoring (IONM) including somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) in patients with pre-operative neurological deficit undergoing posterior spinal correction surgery, and to identify the high-risk factors for failed IONM. Patients with pre-operative neurological deficit undergoing posterior spinal correction surgery between October 2017 and January 2022 were retrospectively reviewed. The presence or absence of SEP and MEP of target muscles were separately recorded. The P37/N50 latency and amplitude of SEP, and the MEP amplitude were measured. Any IONM alerts were also recorded. The IONM performance was compared among patients with different etiologies, levels responsible for neurological deficit, and strength of IONM-target muscles. Patients' demographics were analyzed using the descriptive statistics and were presented with mean ± standard deviation. Comparison analysis was performed using χ2 -test and statistically significant difference was defined as p < 0.05. A total of 270 patients (147 males, 123 females) with an average age of 48.4 ± 36.7 years were involved. The SEP records were available in 371 (68.7%) lower extremities while MEP records were available in 418 (77.4%). SEP alerts were reported in 31 lower extremities and MEP alerts in 22, and new neurological deficit at post-operation was observed in 11. The etiologies of neuromuscular and syndromic indicated relatively lower success rates of IONM, which were 44.1% and 40.5% for SEP, and 58.8% and 59.5% for MEP (p < 0.001). In addition, patients with pre-operative neurological deficit caused by cervical spine and muscle strength lower than grade 4 suffered from higher risk of failed IONM waveforms (p < 0.001). Patients with pre-operative neurological deficit suffered from a higher incidence of failed IONM results. The high-risk for failed IONM waveforms included the neuromuscular and syndromic etiologies, neurological deficit caused by cervical spine, muscle strength lower than grade 4 in patients with pre-operative neurological deficit undergoing posterior spinal correction surgery.

A Novel Approach to Screen for Somatosensory Evoked Potentials in Critical Care.

Somatosensory evoked potentials (SSEPs) help prognostication, particularly in patients with diffuse brain injury. However, use of SSEP is limited in critical care. We propose a novel, low-cost approach allowing acquisition of screening SSEP using widely available intensive care unit (ICU) equipment, specifically a peripheral "train-of-four" stimulator and standard electroencephalograph. The median nerve was stimulated using a train-of-four stimulator, and a standard 21-channel electroencephalograph was recorded to generate the screening SSEP. Generation of the SSEP was supported by visual inspection, univariate event-related potentials statistics, and a multivariate support vector machine (SVM) decoding algorithm. This approach was validated in 15 healthy volunteers and validated against standard SSEPs in 10 ICU patients. The ability of this approach to predict poor neurological outcome, defined as death, vegetative state, or severe disability at 6months, was tested in an additional set of 39 ICU patients. In each of the healthy volunteers, both the univariate and the SVM methods reliably detected SSEP responses. In patients, when compared against the standard SSEP method, the univariate event-related potentials method matched in nine of ten patients (sensitivity = 94%, specificity = 100%), and the SVM had 100% sensitivity and specificity when compared with the standard method. For the 49 ICU patients, we performed both the univariate and the SVM methods: a bilateral absence of short latency responses (n = 8) predicted poor neurological outcome with 0% FPR (sensitivity = 21%, specificity = 100%). Somatosensory evoked potentials can reliably be recorded using the proposed approach. Given the very good but slightly lower sensitivity of absent SSEPs in the proposed screening approach, confirmation of absent SSEP responses using standard SSEP recordings is advised.

Abstract WP113: Cerebrospinal Creatine Kinase BB Isoenzyme: A Biomarker For Predicting Never Awakening In Patients Treated With Therapeutic Hypothermia After Cardiac Arrest

Introduction: Creatine kinase BB isoenzyme (CK-BB) levels in CSF after cardiac arrest (CA) have been shown to predict never awakening though have not been evaluated in patients treated with therapeutic hypothermia (TH). Clinically, CSF CK-BB is tested in those who have not already awakened and are suspected of having a poor prognosis. We aimed to evaluate CSF CK-BB as a prognostic biomarker in the era of TH. Methods: We performed a retrospective cohort study at a single institution of CA patients admitted between 2010 and 2020 and with CSF CK-BB assayed between 36 and 84 hours after CA. We examined the proportion of patients who awakened at hospital discharge and latest follow up in the electronic health record for various CSF CK-BB thresholds. We examined concordance and additive value somatosensory evoked potentials (SSEP). Awakening was defined as following commands or having comprehensible speech. Results: Among 214 eligible patients, mean age was 55 ± 15 years, 72% were male, 33% were non-white, 17% had initial ventricular fibrillation or tachycardia, 90% were out-of-hospital CA, and 83% had TH. A total of 19 (9%) awoke at a mean of 22 ± 28 days. Two patients in a vegetative state at discharge later awoke at 73 (CSF CK-BB 163 U/L) and 101 days (228 U/L). A CSF CK-BB cut-off of ≥ 230 U/L predicted never awakening with a specificity of 100% (binomial 95% CI 82-100%) and a sensitivity of 69% (95% CI 62-76%). When combined with bilaterally absent SSEP, the specificity remained 100% while the sensitivity increased to 80% (95% CI 73-85%). Results were similar after excluding 165 (77%) who had withdrawal of life-sustaining treatment. Discordant findings among 149 patients who had both studies were seen in 13 (9%) with intact SSEP bilaterally but CSF CK-BB ≥ 230 U/L and in 20 (13%) with absent SSEP bilaterally but CSF CK-BB &lt; 230, none of whom awoke. Conclusion: CSF CK-BB levels accurately predict never awakening among CA survivors treated with TH. As part of multimodal prognostic testing with SSEP, the CSF CK-BB cutoff of 230 can optimize sensitivity while maintaining a specificity of 100%. These results are susceptible to a self-fulfilling prophecy, and specificity has a large confidence interval because only a small number of eligible patients awakened.

Editors' Note: Prediction of Regaining Consciousness Despite an Early Epileptiform EEG After Cardiac Arrest

Neuroprognostication after cardiac arrest often remains reliant on neurophysiologic and serologic testing. To better prognosticate outcomes among patients with early epileptiform activity on EEG, Dr. Barbella et al. modeled various EEG predictors of favorable outcome using updated neurophysiologic criteria. Early absence of epileptiform activity, continuous background amplitude with reactivity, and later stimulus-induced rhythmic periodic or ictal discharges (SIRPIDs) strongly predicted favorable long-term outcomes in these patients after cardiac arrest (area under the curve 0.96, 95% CI 0.91–1.00). In a reader response, Dr. Sethi highlights that SIRPIDs may indicate brain reactivity, but they are not associated with cerebral hyperperfusion (as in the case of seizures). Both the investigators and Dr. Sethi agree that later SIRPIDs need not be treated aggressively in these patients. This study adds considerably to the neuroprognostication literature by showing early epileptiform activity may not always be a poor prognostic marker after cardiac arrest. Even in the presence of epileptiform activity, some features indicate a reasonable probability of functional recovery. As the investigators note in their methods—intensive care withdrawal was considered in patients with treatment-resistant myoclonus or status epilepticus, absent somatosensory-evoked potentials, incomplete return of brainstem reflexes, and elevated neuron specific enolase levels. Unsurprisingly, each of these findings strongly predicted poor outcomes. Therefore, the high sensitivity and specificity of the NEC2RAS score for predicting poor outcome does not disentangle it from the possibility of it contributing to the self-fulfilling prophecy. Neuroprognostication after cardiac arrest often remains reliant on neurophysiologic and serologic testing. To better prognosticate outcomes among patients with early epileptiform activity on EEG, Dr. Barbella et al. modeled various EEG predictors of favorable outcome using updated neurophysiologic criteria. Early absence of epileptiform activity, continuous background amplitude with reactivity, and later stimulus-induced rhythmic periodic or ictal discharges (SIRPIDs) strongly predicted favorable long-term outcomes in these patients after cardiac arrest (area under the curve 0.96, 95% CI 0.91–1.00). In a reader response, Dr. Sethi highlights that SIRPIDs may indicate brain reactivity, but they are not associated with cerebral hyperperfusion (as in the case of seizures). Both the investigators and Dr. Sethi agree that later SIRPIDs need not be treated aggressively in these patients. This study adds considerably to the neuroprognostication literature by showing early epileptiform activity may not always be a poor prognostic marker after cardiac arrest. Even in the presence of epileptiform activity, some features indicate a reasonable probability of functional recovery. As the investigators note in their methods—intensive care withdrawal was considered in patients with treatment-resistant myoclonus or status epilepticus, absent somatosensory-evoked potentials, incomplete return of brainstem reflexes, and elevated neuron specific enolase levels. Unsurprisingly, each of these findings strongly predicted poor outcomes. Therefore, the high sensitivity and specificity of the NEC2RAS score for predicting poor outcome does not disentangle it from the possibility of it contributing to the self-fulfilling prophecy.

Are neurophysiologic tests reliable, ultra-early prognostic indices after cardiac arrest?

ObjectivesDetermining early and reliable prognosis in comatose subjects after cardiac arrest is a central component of post–cardiac arrest care both for developing realistic prognostic expectations for families, and for better determining which resources are mobilized or withheld for individual patients. The aim of the study was to evaluate the prognostic accuracy of EEG and SEP patterns during the very early period (within the first 6 h) after cardiac arrest. MethodsWe retrospectively analysed comatose patients after CA, either inside or outside the hospital, in which prognostic evaluation was made during the first 6 h from CA. Prognostic evaluation comprised clinical evaluation (GCS and pupillary light reflex) and neurophysiological (electroencephalography (EEG) and somatosensory evoked potentials (SEP)) studies. Prognosis was evaluated with regards to likelihood of recovery of consciousness and also likelihood of failure to regain consciousness. ResultsForty-one comatose patients after cardiac arrest were included. All patients with continuous and nearly continuous EEG recovered consciousness. Isoelectric EEG was always associated with poor outcome. Burst-suppression, suppression and discontinuous patterns were usually associated with poor outcome although some consciousness recovery was observed. Bilaterally absent SEP responses were always associated with poor outcome. Continuous and nearly continuous EEG patterns were never associated with bilaterally absent SEP. ConclusionsDuring the very early period following cardiac arrest (first 6 h), EEG and SEP maintain their high predictive value to predict respectively recovery and failure of recovery of consciousness. A very early EEG exam allows identification of patients with very high probability of a good outcome, allowing rapid use of the most appropriate therapeutic procedures.

The Prognostic Value of Somatosensory Evoked Potentials in Children After Cardiac Arrest: The SEPIA Study.

Absent cortical somatosensory evoked potentials (SSEPs) reliably predict poor neurologic outcome in adults after cardiac arrest (CA). However, there is less evidence to support this in children. In addition, targeted temperature management, test timing, and a lack of blinding may affect test accuracy. A single-center, prospective cohort study of pediatric (aged 24 hours to 15 years) patients in which prognostic value of SSEPs were assessed 24, 48, and 72 hours after CA. Targeted temperature management (33-34°C for 24 hours) followed by gradual rewarming to 37°C was used. Somatosensory evoked potentials were graded as present, absent, or indeterminate, and results were blinded to clinicians. Neurologic outcome was graded as "good" (score 1-3) or "poor" (4-6) using the Pediatric Cerebral Performance Category scale 30 days after CA and blinded to SSEP interpreter. Twelve patients (median age, 12 months; interquartile range, 2-150; 92% male) had SSEPs interpreted as absent (6/12) or present (6/12) <72 hours after CA. Outcome was good in 7 of 12 patients (58%) and poor in 5 of 12 patients (42%). Absent SSEPs predicted poor outcome with 88% specificity (95% confidence interval, 53% to 98%). One patient with an absent SSEP had good outcome (Pediatric Cerebral Performance Category 3), and all patients with present SSEPs had good outcome (specificity 100%; 95% confidence interval, 51% to 100%). Absence or presence of SSEP was consistent across 24-hour (temperature = 34°C), 48-hour (t = 36°C), and 72-hour (t = 36°C) recordings after CA. Results support SSEP utility when predicting favorable outcome; however, predictions resulting in withdrawal of life support should be made with caution and never in isolation because in this very small sample there was a false prediction of unfavorable outcome. Further prospective, blinded studies are needed and encouraged.

Giant somatosensory evoked potentials are uncommon in patients with post-anoxic coma and paroxysmal electroencephalographic activity

Objectives Post-anoxic encephalopathy (PAE) is a severe neurological condition associated with poor outcome. As part of a multi-modal evaluation, electrophysiological investigations such as electroencephalography (EEG) and somatosensory evoked potentials (SSEPs) have been shown to be reliable outcome predictors in the assessment of comatose survivors, particularly with PAE [3] . The aim of the study was firstly to evaluate the feasibility of performing SSEPs in post-anoxic comatose patients with paroxysmal activity on EEG and secondly to assess the relationship between EEG cortical hyperexcitability and giant cortical N20 SSEPs responses. Methods In this retrospective study between 2016 and 2018, patients with PAE, paroxysmal activity on EEG and available median nerve SSEPs data were included in the analysis. Paroxysmal activity was identified on the EEG performed in the last 48 h preceding SSEPs. We evaluated the N20 amplitude from baseline, and P14-N20 and N20-P24 peak to peak amplitudes. Giant SSEPs were defined as a N20 exceeding 2.7 μV or N20–N24 exceeding 5.5 μV [2] or a late giant component exceeding 5 μV [1] . Results Twenty-one patients were included; 14 men (67%) mean age 66 ± 18 years. A total of 62% of PAE cases were due to cardiac arrest. Nineteen patients died following withdrawal of life support, one died spontaneously and one patient survived. Three patterns of EEG paroxysmal activity were identified: continuous rhythmic activity (n = 3), periodic generalized discharges (GPDs) on a low frequencies background (n = 12) and GPDs on a flat background (burst-suppression) (n = 6). SSEPs were giant in 3 patients (14%), normal in 7 patients (34%), reduced in 3 patients (14%) and absent bilaterally in 8 (38%). Conclusions Our study shows that performing SSEPs is feasible in PAE patients with EEG paroxysmal activity. Giant SSEPs are uncommon in these patients. The EEG cortical hyperexcitability reflects different stages of brain injury, as it can be associated with preserved (even giant), or absent SSEPs.

F108. The prognostic value of median nerve SSEP after cardiac arrest: Evaluation of severity of hypoxic-ischemic encephalopathy by brain autopsies

Introduction The severity of hypoxic-ischemic encephalopathy (HIE) strongly determines outcome after cardiac arrest (CA). Bilaterally absent cortical median nerve somatosensory evoked potentials (SSEPs) have been shown to accurately predict poor prognosis. However, self-fulfilling prophecy due to withdrawal of life-sustaining therapy is an important bias in prognostication studies on CA patients. Brain autopsies in patients who died after CA provide a unique opportunity to verify prognostic parameters such as SSEPs. Methods We retrospectively identified CA patients from university hospitals in Berlin, Germany, Lund, Sweden and Arhus, Denmark, who died after initially successful resuscitation and for whom SSEPs for neuro-prognostication and brain autopsy were available. We blindly determined presence/absence and, if applicable, cortical peak-to-peak SSEP amplitudes from original recordings. Severity of HIE was quantified histopathologically according to the selective eosinophilic neuronal death (SEND) score. Results We identified 58 CA autopsy patients who had been investigated with SSEP. All 21 patients with bilaterally absent SSEP and all 5 with cortical SSEP amplitudes below 0.5 μV had severe HIE (SEND 2–4 in cortical regions). The highest cortical SSEP amplitude in a patient with severe HIE was 2.7 μV, all 11 patients with higher amplitudes had no/moderate HIE (SEND 0–1 in cortical regions). Conclusion We did not find evidence for a self-fulfilling prophecy in the prediction of poor neurological outcome by SSEP after cardiac arrest. Bilaterally absent cortical SSEP and very low SSEP amplitudes indicated histopathologically severe HIE whereas cortical SSEP amplitudes above 2.7 μV indicated absence of severe HIE.

S24. The combination of electroencephalogram (EEG) and somatosensory evoked potentials (SSEP) for prognostication following anoxic brain injury – A pilot study from an Academic Hospital in Ireland

Introduction Clinical evaluation for prognosis of comatose patients following hypoxic ischaemic encephalopathy in the intensive care setting is difficult. Electroencephalogram (EEG) and somatosensory evoked potentials (SSEP) both hold value as predictive tools when assessing outcome following cardiac arrest (CA) and hypoxic brain injury. EEG may be used for diagnosis and prognostication on a poorly responsive patient following catastrophic brain injury. There is evidence that loss of EEG reactivity is a strong risk factor for mortality or poor neurological recovery following cardiac arrest, however, bilaterally absent SSEPs remain the most reliable predictor of poor outcome. SSEPs have not been widely available in Ireland as a component of neurophysiologic investigation following hypoxic ischaemic encephalopathy. The aim of this review is to assess and compare the predictive value of EEG and SSEP separately as single modality testing and then subsequently combine both tests for a multimodal approach to predict poor outcome following anoxic brain injury. Is a multimodal approach mandatory? Methods Seventeen cardiac arrest survivors were included in this review. We adopted a multimodal approach to neurophysiologic investigations in the ICU setting with prospective evaluation of patients of hypoxic ischaemic encephalopathy after CA. EEG and SSEPs were performed at normothermia. EEG background reactivity to painful stimulation was tested. Results Of the 17 patients included in the review, two survived to discharge and 15 subsequently died during hospitalisation. EEG was utilised as a marker for poor outcome combining malignant EEG patterns and absent reactivity of background rhythms. 11 out of 17 fitted into the “poor outcome” category for EEG, all of whom died. Bilateral absent N20 cortical responses were utilised for poor outcome, 9 out of 17 fitted into the “poor outcome” category, all of whom went on to die. However, there were eight patients included showing present N20s, this is not prognostic of a favourable outcome. A combination of EEG and SSEP was needed to predict outcome. The EEG showed malignant EEG patterns and unreactive background in 2 of the present N20 patients who subsequently went on to die. Conclusion The EEG represents a useful tool for prognostic assessment. Unreactive EEG background and malignant EEG patterns are incompatible with good long term recovery. In settings without access to SSEPs this can be helpful, however, a bilaterally absent somatosensory evoked potential is still the most reliable predictor for poor outcome. Throughout our review a multimodal approach is shown to be favourable when assessing Hypoxic Ischemic Encephalopathy. This approach, as described above, was necessary to predict outcome in cases where the N20 cortical response was present, thus optimising prognostic accuracy when assessing hypoxic brain injury in the ICU. Early identification of patients without the potential for recovery of brain function may result in unnecessary prolongation of medical therapy.

T87. EEG and simultaneously recorded SEPs in evaluation of newborns with hypoxic ischemic encephalopathy or stroke in the NICU

Introduction Differential diagnostics and outcome prediction in newborns presenting with seizures or encephalopathy remain difficult in the bedside. The objectives of the present study were (i) to determine the accuracy of simultaneously recorded EEG and somatosensory evoked potentials (SEPs) in differentiating between hypoxic-ischemic encephalopathy (HIE) and stroke as the underlying etiology of neonatal seizures or encephalopathy and (ii) to determine the accuracy of EEG and SEPs and their combination for predicting outcome in newborns with HIE or stroke. Methods The study comprised of 133 newborns (gestational age > 34 weeks) that underwent a clinically indicated EEG and simultaneous SEPs in the acute phase of their illness. 102 of the newborns had HIE and 31 had stroke. EEG background was scored as continuous (sleep stages identifiable and EEG continuous at least in active sleep or awake state) or discontinuous (sleep stages not identifiable and EEG not continuous at any time during the recording). The SEPs were classified as bilaterally absent, unilaterally absent, or bilaterally present. Outcome was evaluated from medical records at approximately 1–1.5 years age. Death, cerebral palsy, severe mental retardation, and epilepsy were considered as unfavorable outcomes. Normal or mildly abnormal development (e.g. mild motor or language delay) were considered as favorable outcomes. Results The combinations of EEG and SEP abnormalities were indicative of etiology (HIE vs stroke) and predictive of outcome. If the EEG was discontinuous, the etiology was always HIE (33 newborns) regardless of SEPs. Furthermore, if the EEG was continuous, but SEPs were uni- (9 newborns) or bilaterally (1 newborn) absent, the etiology was always stroke. Normal SEPs and continuous EEG occurred in 69 newborns with HIE and 21 newborns with stroke, and hence in these newborns the distinction between the etiologies could not be made with the present EEG-SEP criteria. This combination was, however, highly predictive of a favorable outcome regardless of the etiology: The outcome was favorable in 67/69 of those HIE and 20/21 of those with stroke. On the contrary, bi- or unilaterally absent SEPs were associated with poor outcome in all newborns with HIE (22/22) and all but two newborns with stroke (8/10). Furthermore, in newborns with HIE, even if the EEG was discontinuous but SEPs were bilaterally present, the outcome was likely to be favorable (8/11 newborns). Conclusion EEG-SEP is useful in bedside differential diagnostics between HIE and stroke in newborns presenting with seizures or general signs of encephalopathy. Furthermore, EEG-SEP is accurate in outcome prediction in both etiologies.

P 92 The prognostic value of somatosensory evoked potentials in patients with severe traumatic brain injury

Objective The prognosis after traumatic coma is often unclear. It can be difficult to predict the neurological outcome using clinical criteria or imaging techniques alone. In patients with severe traumatic brain injury (TBI) median somatosensory evoked potentials (SSEPs) serve as an accepted prognostic tool. They are widely available electrophysiological tests. We evaluated the prognostic value of SSEPs in comatous patients in the intensive care unit regarding longterm outcome. Methods We retrospectively analyzed 50 patients (18–75 years) with severe brain trauma (GCS Results Preliminary results demonstrate that 90% of the patients with bilaterally absent or abnormal SSEP results had fatal prognosis or severe neurological deficits. Unilaterally absent SSEP had a negative predictive value with a rather poor GOS. Patients with GOS 4 and 5 could be predicted by bilateral normal SSEP. Conclusion Somatosensory evoked potentials are widely available electrophysiological tests and can provide an objective biomarker of a neurological outcome and assist in reliable predicting of the prognosis in patients with TBI. They should therefore be used more often for intensive care unit patients.

Electroencephalography Predicts Poor and Good Outcomes After Cardiac Arrest: A Two-Center Study*

The prognostic role of electroencephalography during and after targeted temperature management in postcardiac arrest patients, relatively to other predictors, is incompletely known. We assessed performances of electroencephalography during and after targeted temperature management toward good and poor outcomes, along with other recognized predictors. Cohort study (April 2009 to March 2016). Two academic hospitals (Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; Mayo Clinic, Rochester, MN). Consecutive comatose adults admitted after cardiac arrest, identified through prospective registries. All patients were managed with targeted temperature management, receiving prespecified standardized clinical, neurophysiologic (particularly, electroencephalography during and after targeted temperature management), and biochemical evaluations. We assessed electroencephalography variables (reactivity, continuity, epileptiform features, and prespecified "benign" or "highly malignant" patterns based on the American Clinical Neurophysiology Society nomenclature) and other clinical, neurophysiologic (somatosensory-evoked potential), and biochemical prognosticators. Good outcome (Cerebral Performance Categories 1 and 2) and mortality predictions at 3 months were calculated. Among 357 patients, early electroencephalography reactivity and continuity and flexor or better motor reaction had greater than 70% positive predictive value for good outcome; reactivity (80.4%; 95% CI, 75.9-84.4%) and motor response (80.1%; 95% CI, 75.6-84.1%) had highest accuracy. Early benign electroencephalography heralded good outcome in 86.2% (95% CI, 79.8-91.1%). False positive rates for mortality were less than 5% for epileptiform or nonreactive early electroencephalography, nonreactive late electroencephalography, absent somatosensory-evoked potential, absent pupillary or corneal reflexes, presence of myoclonus, and neuron-specific enolase greater than 75 µg/L; accuracy was highest for early electroencephalography reactivity (86.6%; 95% CI, 82.6-90.0). Early highly malignant electroencephalography had an false positive rate of 1.5% with accuracy of 85.7% (95% CI, 81.7-89.2%). This study provides class III evidence that electroencephalography reactivity predicts both poor and good outcomes, and motor reaction good outcome after cardiac arrest. Electroencephalography reactivity seems to be the best discriminator between good and poor outcomes. Standardized electroencephalography interpretation seems to predict both conditions during and after targeted temperature management.

Can somatosensory and visual evoked potentials predict neurological outcome during targeted temperature management in post cardiac arrest patients?

PurposesIn cardiac arrest patients treated with targeted temperature management (TTM), it is not certain if somatosensory evoked potentials (SEPs) and visual evoked potentials (VEPs) can predict neurological outcomes during TTM. The aim of this study was to investigate the prognostic value of SEPs and VEPs during TTM and after rewarming. MethodsThis retrospective cohort study included comatose patients resuscitated from cardiac arrest and treated with TTM between March 2007 and July 2015. SEPs and VEPs were recorded during TTM and after rewarming in these patients. Neurological outcome was assessed at discharge by the Cerebral Performance Category (CPC) Scale. ResultsIn total, 115 patients were included. A total of 175 SEPs and 150 VEPs were performed. Five SEPs during treated with TTM and nine SEPs after rewarming were excluded from outcome prediction by SEPs due to an indeterminable N20 response because of technical error. Using 80 SEPs and 85 VEPs during treated with TTM, absent SEPs yielded a sensitivity of 58% and a specificity of 100% for poor outcome (CPC 3–5), and absent VEPs predicted poor neurological outcome with a sensitivity of 44% and a specificity of 96%. The AUC of combination of SEPs and VEPs was superior to either test alone (0.788 for absent SEPs and 0.713 for absent VEPs compared with 0.838 for the combination). After rewarming, absent SEPs and absent VEPs predicted poor neurological outcome with a specificity of 100%. When SEPs and VEPs were combined, VEPs slightly increased the prognostic accuracy of SEPs alone. Although one patient with absent VEP during treated with TTM had a good neurological outcome, none of the patients with good neurological outcome had an absent VEP after rewarming. ConclusionAbsent SEPs could predict poor neurological outcome during TTM as well as after rewarming. Absent VEPs may predict poor neurological outcome in both periods and VEPs may provide additional prognostic value in outcome prediction.

Neonatal somatosensory evoked potentials persist during hypothermia.

Treatment with therapeutic hypothermia has challenged the use of amplitude-integrated electroencephalography in predicting outcomes after perinatal asphyxia. In this study, we assessed the feasibility and gain of somatosensory evoked potentials (SEP) during hypothermia. This retrospective study comprised neonates from 35+6 to 42+2 gestational weeks and treated for asphyxia or hypoxic-ischaemic encephalopathy at Helsinki University Hospital between 14 February 2007 and 23 December 2009. This period was partly before the introduction of routine therapeutic hypothermia, which enabled us to include normothermic neonates who would these days receive hypothermia treatment. We analysed SEPs from 47 asphyxiated neonates and compared the results between 23 normothermic and 24 hypothermic neonates. Our data showed that hypothermia led to SEP latencies lengthening by a few milliseconds, but the essential gain for predicting outcomes by SEPs was preserved during hypothermia. Of the 24 hypothermic neonates, bilaterally absent SEPs were associated with poor outcome in 2/2 neonates, normal SEPs were associated with good outcomes in 13/15 neonates and 5/7 neonates with unilaterally absent or grossly delayed SEPs had a poor outcome. Our findings indicated that SEPs were a reliable tool for evaluating the somatosensory system in asphyxiated neonates in both normothermic and hypothermic conditions.

79. Status epileptics and myoclonus in comatose patients after cardiac arrest: To treat or not to treat

Status epilepticus and myoclonus are common in comatose patients after cardiac arrest (Krumholz et al., 1988; Young et al., 1990). There is no consensus on when and for how long to treat this condition. This point became more relevant after introduction of therapeutic hypothermia (TH) because of some patients with MS treated with TH recovered consciousness (Rossetti et al., 2009). We propose a treatment protocol based on clinical-EEG features and somatosensory evoked potentials (SEPs) as prognostic indicator. In patients with absent SEPs we do not treat aggressively with AED considering the poor outcome. In patients with preserved SEPs we treat myoclonus if associated with GPEDs, convulsive status epilepticus and non convulsive status epilepticus (Beniczky et al., 2013). We use a combination of AED (valproate, levetiracetam) with sedation (propofol or midazolam). We present two representative cases in which we describe in more detail our therapeutic approach.

Neurological prognostication after cardiac arrest and targeted temperature management 33 °C versus 36 °C: Results from a randomised controlled clinical trial

BackgroundThe reliability of some methods of neurological prognostication after out-of-hospital cardiac arrest has been questioned since the introduction of induced hypothermia. The aim of this study was to determine whether different treatment temperatures after resuscitation affected the prognostic accuracy of clinical neurological findings and somatosensory evoked potentials (SSEP) in comatose patients. MethodsWe calculated sensitivity and false positive rate for Glasgow Coma Scale motor score (GCS M), pupillary and corneal reflexes and SSEP to predict poor neurological outcome using prospective data from the Target Temperature Management after Out-of-Hospital Cardiac Arrest Trial which randomised 939 comatose survivors to treatment at either 33°C or 36°C. Poor outcome was defined as severe disability, vegetative state or death (Cerebral Performance Category scale 3–5) at six months. Results313 patients (33%) were prognostically assessed; 168 in the 33°C, and 145 in the 36°C group. A GCS M ≤2 had a false positive rate of 19.1% to predict poor outcome due to nine false predictions. Bilaterally absent pupillary reflexes had a false positive rate of 2.1% and absent corneal reflexes had a false positive rate of 2.2% due to one false prediction in each group. The false positive rate for bilaterally absent SSEP N20-peaks was 2.6%. ConclusionsBilaterally absent pupillary and corneal reflexes and absent SSEP N20-peaks were reliable markers of a poor prognosis after resuscitation from out-of-hospital cardiac arrest but low GCS M score was not. The reliability of the tests was not altered by the treatment temperature.

Can we predict neurological outcome following out-of-hospital cardiac arrest (OHCA) and therapeutic hypothermia?

Can we predict neurological outcome following out-of-hospital cardiac arrest (OHCA) and therapeutic hypothermia?

Positive prognostication from median-nerve somatosensory evoked cortical potentials.

The bilateral absence of the cortical N20 median-nerve somatosensory evoked potential (SSEP) is a strong predictor of poor outcome from coma. However, when N20s are present, accurate prognostication is challenging. Here, we investigated the potential for later SSEP components to help disambiguate outcome in these cases. In a retrospective review of data from two intensive care units, the amplitudes and latencies of the N20, P25, and N35 components of 28 patients in coma were quantified and related to outcome at discharge from primary care (average 1-month post-injury). Only patients who had survived primary care were included in order to avoid self-fulfilling prophecies, and to focus outcome prediction on those patients with relatively present SSEPs. The amplitudes of the N20 and N35 components (averaged across hemispheres) significantly predicted the range of outcomes beyond death. Abnormal amplitudes of the N20 and N35--as derived from a healthy control group--were significantly associated with poor outcome. The relative latencies of the cortical components were not related to outcome. While it is well documented that absent SSEPs are highly predictive of poor outcome, the current data indicate that the relative preservation (absolute amplitude) of "present" N20 and N35 SSEP components can also provide predictive value and thereby inform clinicians and families with decision-making in coma. Further prospective study will elucidate the relative contributions of etiology to the predictive power of these SSEP measures.

Absent median somatosensory evoked potential is a predictor of type I complex regional pain syndrome after stroke

Purpose: The objective was to determine whether the abnormal finding of somatosensory evoked potentials (SEPs) associated with the development of type I complex regional pain syndrome (CRPS) after stroke. Methods: This was a retrospective study conducted from January, 2003, to December, 2007. Seventy patients were confirmed as CRPS type I, and one hundred and eighty-two patients were assigned to the control group. The initial clinical data were reviewed including age, gender, main type of stroke, lateralization and location of the lesion, presence of glenohumeral subluxation, and the development of CRPS. Somatosensory evoked potentials tests (SEP) in median nerve (N20) and posterior tibial nerve (P37) were performed. Results: CRPS groups revealed significantly higher incidence of the absent and abnormal hemiplegic median SEP, hemorrhagic stroke, and glenohumeral subluxation (GHS). Binary logistic regression analysis indicated that GHS (exp.(B) = 4.083, p < 0.01) with the absent median SEP (exp.(B) = 3.246, p < 0.01) were significant independent predictors of CRPS onset. Conclusions: In conclusion, GHS and the absent median SEP at sub-acute phase of stroke were primary predictors of the onset of post-stoke CRPS.Implications for RehabilitationRecent investigations have suggested that autonomic, motor and somatosensory abnormalities of CRPS are impairments involving the central nervous system (CNS) as well as the peripheral neurogenic inflammatory process. However, the understanding of the pathophysiology of CRPS is still far from complete.The absence of SEP at the sub-acute stage of stroke correlated with the onset of post-stroke CRPS type I.The SEP evaluation at the sub-acute period after stroke might be generally used for predicting the concomitant development of post-stroke CRPS type I as well as functional recovery after stroke.

The prognostic value of gray-white-matter ratio in cardiac arrest patients treated with hypothermia

BackgroundMild therapeutic hypothermia alters the validity of a number of parameters currently used to predict neurological outcome after cardiac arrest and resuscitation. Thus, additional parameters are needed to increase certainty of early prognosis in these patients. A promising new approach is the determination of the gray-white-matter ratio (GWR) in cranial computed tomography (CCT) obtained early after resuscitation. It is not known how GWR relates to established outcome parameters such as neuron specific enolase (NSE) or somatosensory evoked potentials (SSEP).MethodsCardiac arrest patients (n = 98) treated with hypothermia were retrospectively analyzed with respect to the prognostic value of GWR, NSE and SSEP.ResultsA GWR < 1.16 predicted poor outcome with 100% specificity and 38% sensitivity. In 62 patients NSE, SSEP and CCT were available. The sensitivity of poor outcome prediction by both NSE > 97 μg/L and bilateral absent SSEP was 43%. The sensitivity increased to 53% in a multi-parameter approach predicting poor outcome using at least two of the three parameters (GWR, NSE and SSEP).ConclusionOur results suggest a strong association of a low GWR with poor outcome following cardiac arrest. Determination of the GWR increases the sensitivity in a multi-parameter approach for prediction of poor outcome after cardiac arrest.