The Utility of EEG,SSEP, and Other Neurophysiologic Tools to Guide Neurocritical Care

Neuromonitoring is an emerging field that aims to characterize real-time neurophysiology to tailor therapy for acute injuries of the central nervous system. While cardiac telemetry has been used for decades among patients requiring critical care of all kinds, neurophysiology and neurotelemetry has only recently emerged as a routine screening tool in comatose patients. The increasing utilization of electroencephalography in comatose patients is primarily due to the recognition of the common occurrence of nonconvulsive seizures among comatose patients, the development of quantitative measures to detect regional ischemia, and the appreciation of electroencephalography phenotypes that indicate prognosis after cardiac arrest. Other neuromonitoring tools, such as somatosensory evoked potentials have a complementary role, surveying the integrity of the neuroaxis as an indicator of prognosis or illness progression in both acute brain and spinal injuries.     

Initial Troponin Level as a Predictor of Prognosis in Patients with Intracerebral Hemorrhage

Objective

It has been suggested that elevated cardiac troponin T (cTnT) level is a marker of increased risk of mortality in acute ischemic stroke and subarachnoid hemorrhage (SAH). However, the association of serum cTnT level and prognosis of intracerebral hemorrhage (ICH) has been sparsely investigated. The aim of this study was to identify the relationship between cTnT level and the outcome in patients with spontaneous ICH.

Methods

We retrospectively investigated 253 patients identified by a database search from records of patients admitted in our department for ICH between January 1, 2003 and December 31, 2007. The patients were divided into 2 groups; the patients in group 1 (n=225) with serum cTnT values of 0.01 ng/mL or less, and those in group 2 (n=28) with serum cTnT values greater than 0.01 ng/mL.

Results

The serum cTnT level was elevated in 28 patients. There were significant differences in sex, hypertension, creatine kinase-myocardial band, midline shift, side of hematoma, and presence of intraventricular hemorrhage between the 2 groups. Logistic regression analysis identified the level of consciousness on admission, cTnT and midline shift as independent predictors of hospital mortality.

Conclusion

Theses results suggest that increased serum cTnT level at admission is associated with in-hospital mortality and the addition of a serum cTnT assay to routine admission testing should be considered in patients with ICH.     

Serum Neuron-Specific Enolase Levels from the Same Patients Differ Between Laboratories: Assessment of a Prospective Post-cardiac Arrest Cohort

Background

In comatose post-cardiac arrest patients, a serum neuron-specific enolase (NSE) level of >33 μg/L within 72 h was identified as a reliable marker for poor outcome in a large Dutch study (PROPAC), and this level was subsequently adopted in an American Academy of Neurology practice parameter. Later studies reported that NSE >33 μg/L is not a reliable predictor of poor prognosis. To test whether different clinical laboratories contribute to this variability, we compared NSE levels from the laboratory used in the PROPAC study (DLM-Nijmegen) with those of our hospital’s laboratory (ARUP) using paired blood samples.

Methods

We prospectively enrolled cardiac arrest patients who remained comatose after resuscitation. During the first 3 days, paired blood samples for serum NSE were drawn at a median of 10 min apart. After standard preparation for each lab, one sample was sent to ARUP laboratories and the other to DLM-Nijmegen.

Results

Fifty-four paired serum samples from 33 patients were included. Although the serum NSE measurements correlated well between laboratories (R = 0.91), the results from ARUP were approximately 30 % lower than those from DLM-Nijmegen. Therapeutic hypothermia did not affect this relationship. Two patients had favorable outcomes after hypothermia despite NSE levels measured by DLM-Nijmegen as >33 μg/L.

Conclusions

Absolute serum NSE levels of comatose cardiac arrest patients differ between laboratories. Any specific absolute cut-off levels proposed to prognosticate poor outcome should not be used without detailed data on how neurologic outcomes correspond to a particular laboratory’s method, and even then only in conjunction with other prognostic variables.     

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.     

A priority treatment of the intraventricular hemorrhage (IVH) should be performed in the patients suffering intracerebral hemorrhage with large IVH

Background

In patients suffering from intracerebral hemorrhage (ICH) with ventricular hemorrhage (IVH), the IVH severity is thought to be associated with prognosis. Therefore, treating IVH may be a beneficial therapeutic target. In this study, by examining the associations among IVH severity, hydrocephalus, initial level of consciousness and prognosis, we attempted to identify which grade of IVH severity should be considered for surgical treatment.

Methods

One hundred twenty-nine patients with spontaneous supratentorial ICH treated in our hospital between 2005 and 2006 were screened in this study. Of these patients, 100 with an ICH volume less than 60 ml were categorized into either the ICH patients without IVH (no-IVH) group (n = 65) or the ICH patients with IVH (IVH) group (n = 35). The Karnofsky Performance Status (KPS) scale assessed at the time of discharge was employed as an outcome index, and a KPS score of ≤40 was defined as the bedridden state. Age, gender, hemorrhage location, volume of ICH, IVH grade (according to the Graeb score), acute hydrocephalus, surgical ICH removal, and ventricular drainage were selected for univariate analyses with logistic regression.

Results

Elderly patients, IVH volume, acute hydrocephalus, and poor initial level of consciousness were significantly associated with an unfavorable prognosis in the IVH group. Poor level of consciousness was significantly dependent on acute hydrocephalus, and significantly more occurrences of acute hydrocephalus were found in patients with a high IVH volume (Graeb score ≥6) than in patients with low to moderate IVH volume (Graeb score ≤6).

Conclusions

IVH severity influenced the occurrence of acute hydrocephalus and initial level of consciousness, which was significantly associated with prognosis. Our results suggest that priority treatment of the IVH should be given to those ICH patients with IVH admitted with a Graeb score of 6 or more.     

Early EEG Monitoring for Detecting Postanoxic Status Epilepticus during Therapeutic Hypothermia: A Pilot Study

Objective  

To determine whether routine electroencephalography (EEG) detected electrical status epilepticus (ESE), masked by neuromuscular blockade, in comatose cardiac-arrest survivors receiving therapeutic hypothermia.     

Clinical Outcome After a Reactive Hypothermic EEG Following Cardiac Arrest

Background

Reactive electroencephalography (EEG) background during therapeutic hypothermia (TH) is related to favorable prognosis after cardiac arrest (CA), but its predictive value is not 100 %. The aim of this study was to investigate outcome predictors after a first reactive EEG recorded during TH after CA.

Methods

We studied a cohort of consecutive comatose adults admitted between February 2008 and November 2012, after successful resuscitation from CA, selecting patients with reactive EEG during TH. Outcome was assessed at three months, and categorized as survivors and non-survivors (no patient was in vegetative state). Demographics, clinical variables, EEG features, serum neuron-specific enolase (NSE) and procalcitonin, were compared using uni- and multivariable analyses.

Results

A total of 290 patients were treated with TH after cardiac arrest; 146 had an EEG during TH, which proved reactive in 90 of them; 77 (86 %) survived and 13 (14 %) died (without recovery from coma). The group of non-survivors had a higher occurrence of discontinuous EEG (p = 0.006; multivariate analysis p = 0.026), and a higher serum NSE peak (p = 0.021; multivariate analysis p = 0.014); conversely, demographics, and other clinical variables including serum procalcitonin did not differ.

Conclusions

A discontinuous EEG and high serum NSE are associated with mortality after CA in patients with poor outcome despite a reactive hypothermic EEG. This suggests more severe cerebral damage, but not to higher extent of systemic disease.     

Brain Injuries during Intraoperative Ventriculostomy in the Aneurysmal Subarachnoid Hemorrhage Patients

Objective

Intraoperative ventriculostomy is widely adopted to make the slack brain. However, there are few reports about hemorrhagic or parenchymal injuries after ventriculostomy. We tried to analyze and investigate the incidence of these complications in a consecutive series of patients with aneurysmal subarachnoid hemorrhage (SAH).

Methods

From September 2006 to June 2007, 43 patients underwent surgical clipping for aneurysmal SAH at our hospital. Among 43 patients, we investigated hemorrhagic or parenchymal injuries after intraoperative ventriculostomy using postoperative computed tomographic scan in 26 patients. After standard pterional craniotomy, ventriculostomy catheter was inserted perpendicular to the cortical surface along the bisectional imaginary line from Paine''s point.

Results

Hemorrhagic injuries were detected in 12 of 26 patients (46.2%). Mean systolic blood pressure during anesthesia was with in statistically significant parameter related to hemorrhage (p = 0.006). On the other hand, parenchymal injuries were detected in 11 of 26 patients (42.3%). Female and the amount of infused mannitol during anesthesia showed statistically significant parameters related to parenchymal injury (p = 0.005, 0.04, respectively). However, there were no ventriculostomy-related severe complications.

Conclusion

In our series, hemorrhagic or parenchymal injuries after intraoperative ventriculostomy occurred more commonly than previously reported series in aneurysmal SAH patients. Although the clinical outcomes of complications are generally favorable, neurosurgeon must keep in mind the frequent occurrence of brain injury after intraoperative ventriculostomy in the acute stage of aneurysmal SAH.     

Frequency and Timing of Nonconvulsive Status Epilepticus in Comatose Post-Cardiac Arrest Subjects Treated with Hypothermia

Background  

Therapeutic hypothermia (TH) improves outcomes in comatose patients resuscitated from cardiac arrest. However, nonconvulsive status epilepticus (NCSE) may cause persistent coma. The frequency and timing of NCSE after cardiac arrest is unknown.     

Cardiac Troponin T Elevation After Stroke: Relationships Between Elevated Serum Troponin T, Stroke Location, and Prognosis

Background and Purpose

Elevation of serum cardiac troponin T (cTnT) is regarded as a specific marker of acute coronary syndrome. Serum cTnT can be increased in patients with acute ischemic stroke, but its clinical implications remain unclear. The aim of this study was to identify the relationships between elevated cTnT and stroke severity, location, and prognosis.

Methods

From January 2005 to December 2006, this study recruited 455 consecutive patients who were admitted to Kangbuk Samsung Hospital due to acute ischemic stroke within 3 days of onset, which was confirmed by diffusion magnetic resonance imaging. A total of 416 patients was finally included and divided into 2 groups: an elevated cTnT group (n=45) and a normal cTnT group (n=371). The short-term prognosis was assessed by 30-day modified Rankin Scale responder analysis was compared between the two groups.

Results

Serum cTnT was elevated in 10.8% of cases, with elevated cTnT associated with greater stroke severity, as assessed by the National Institutes of Health Stroke Scale score, Insular-lobe involvement was more common in patients with elevated cTnT than in the normal cTnT group. Short-term prognosis was more unfavorable in the elevated cTnT group than in the normal cTnT group. Multivariate regression analysis indicated that elevated cTnT was independently related to insular involvement, cardioembolism, and unfavorable outcome.

Conclusions

Elevated cTnT in acute ischemic stroke was associated with severe neurological deficits at stroke onset and damages to the insular lobe. The outcome of acute ischemic stroke was worse for patients with elevated cTnT than for those with normal cTnT. The pathomechanism underlying acute ischemic stroke and subclinical myocardial damage warrants further study.     

Clinical MRI Interpretation for Outcome Prediction in Cardiac Arrest

Background

In clinical practice, magnetic resonance imaging (MRI) is commonly used to assess the severity of a cardiac arrest patient??s cerebral injury, utilizing treating neurologists?? imaging interpretation. We sought to determine whether clinical interpretation of diffusion-weighted imaging (DWI) helps to determine poor outcome in comatose cardiac arrest patients.

Methods

We analyzed 80 consecutive MRIs from patients in coma following cardiac arrest. Each study was graded as ??normal?? or ??abnormal restricted diffusion?? in pre-specified brain regions by two blinded stroke neurologists. Poor outcome was defined as a modified Rankin Scale (mRS) score >4 at 3?months. Formal interpretations of neuroimaging by non-blinded neuroradiologists were compared with the blinded reviews by the stroke neurologists.

Results

DWI abnormalities were highly sensitive (98.5?%) but only modestly specific (46.2?%) for predicting poor neurological outcome. Inter-observer reliability was moderate (kappa?=?0.49?±?0.32), with 91?% agreement between study observers, and no significant differences in study observers?? interpretations (p?=?0.125). There were, however, significant differences between the study observers and the clinical neuroradiologists in identifying studies showing evidence of global hypoxic-ischemic injury (p?=?0.001).

Conclusions

The qualitative evaluation of imaging abnormalities by stroke physicians in comatose cardiac arrest patients is a highly sensitive method of predicting poor outcome, but with limited specificity.     

Large inter-rater variability on EEG-reactivity is improved by a novel quantitative method

Objective

To assess inter-rater agreement on EEG-reactivity (EEG-R) in comatose patients and compare it with a quantitative method (QEEG-R).

高血压脑出血昏迷患者脑功能状态监测的临床研究

目的 探讨高血压脑出血后昏迷患者脑功能状态监测的应用及其对预后评估的作用. 方法 回顾性分析119例基底节区高血压脑出血后昏迷患者的临床资料及脑功能状态监测数据,根据随访3个月的预后情况将患者分为清醒、昏迷及死亡3组,比较各组患者在入院时、入院后第3天、第7天及第14天时脑状态指数(CSI)的差异性及变化情况. 结果 119例患者入院时的CSI值与GCS评分呈正相关关系(Spearman相关系数rp=0.816,P=0.000).各组患者发病后不同时间CSI值有差别,清醒组CSI值最高,昏迷组最低,统计分析显示各组患者在入院时、入院后第3天、第7天及第14天时CSI值差异均有统计学意义(P＜0.05). 结论 脑功能状态监测可以反映患者的脑功能状态水平,在临床上应用CSI值连续监测高血压脑出血后昏迷患者的脑功能状态有助于预后评估及指导诊治.     

Proving cortical death after vascular coma: Evoked potentials,EEG and neuroimaging

Objectives

Several studies have shown that bilateral abolition of somatosensory evoked potentials after a nontraumatic coma has 100% specificity for nonawakening with ethical consequences for active care withdrawal. We propose to evaluate the prognostic value of bilateral abolished cortical components of SEPs in severe vascular coma.

Therapeutic Hypothermia after Cardiac Arrest: Performance Characteristics and Safety of Surface Cooling with or without Endovascular Cooling

Introduction

Various methods are available to induce and maintain therapeutic hypothermia after cardiac arrest, but little data is available comparing device-mediated cooling to simple surface methods in this setting.

Methods

To assess the performance characteristics of simple surface cooling with or without an endovascular cooling catheter system, we retrospectively reviewed all cases of hypothermia for comatose survivors of cardiac arrest treated at a single academically affiliated urban hospital. Forty two comatose survivors of cardiac arrest were treated over a 3.5-year period. Hypothermia was induced and maintained by simple surface methods (ice packs, cooling blankets) with or without placement of an endovascular cooling catheter system with automated temperature feedback regulation.

Results

Overall, the rate of active cooling was not different between patients treated with endovascular catheter-assisted hypothermia and patients treated with surface cooling alone. However, use of a larger (14 F) catheter was associated with faster cooling rates. Maintenance of goal temperature (33°C) was far better controlled with the use of a cooling catheter. Use of surface cooling alone was associated with significant temperature overshoot. Patients treated with surface cooling alone spent more time bradycardic.

Conclusion

Use of an endovascular cooling catheter as part of a treatment protocol for hypothermia after cardiac arrest provides better control during maintenance of hypothermia, preventing temperature overshoot. Active cooling rates may be enhanced by the use of a larger cooling catheter.     

Predisposing Factors Related to Shunt-Dependent Chronic Hydrocephalus after Aneurysmal Subarachnoid Hemorrhage

Objective

Hydrocephalus is a common sequelae of aneurysmal subarachnoid hemorrhage (SAH) and patients who develop hydrocephalus after SAH typically have a worse prognosis than those who do not. This study was designed to identify factors predictive of shunt-dependent chronic hydrocephalus among patients with aneurysmal SAH, and patients who require permanent cerebrospinal fluid diversion.

Methods

Seven-hundred-and-thirty-four patients with aneurysmal SAH who were treated surgically between 1990 and 2006 were retrospectively studied. Three stages of hydrocephalus have been categorized in this paper, i.e., acute (0-3 days after SAH), subacute (4-13 days after SAH), chronic (≥14 days after SAH). Criteria indicating the occurrence of hydrocephalus were the presence of significantly enlarged temporal horns or ratio of frontal horn to maximal biparietal diameter more than 30% in computerized tomography.

Results

Overall, 66 of the 734 patients (8.9%) underwent shunting procedures for the treatment of chronic hydrocephalus. Statistically significant associations among the following factors and shunt-dependent chronic hydrocephalus were observed. (1) Increased age (p < 0.05), (2) poor Hunt and Hess grade at admission (p < 0.05), (3) intraventricular hemorrhage (p < 0.05), (4) Fisher grade III, IV at admission (p < 0.05), (5) radiological hydrocephalus at admission (p < 0.05), and (6) post surgery meningitis (p < 0.05) did affect development of chronic hydrocephalus. However the presence of intracerebral hemorrhage, multiple aneurysms, vasospasm, and gender did not influence on the development of shunt-dependent chronic hydrocephalus. In addition, the location of the ruptured aneurysms in posterior cerebral circulation did not correlate with the development of shunt-dependent chronic hydrocephalus.

Conclusion

Hydrocephalus after aneurysmal SAH seems to have a multifactorial etiology. Understanding predisposing factors related to the shunt-dependent chronic hydrocephalus may help to guide neurosurgeons for better treatment outcomes.     

EEG hyper-connectivity in high-risk infants is associated with later autism

Background

It has been previously reported that structural and functional brain connectivity in individuals with autism spectrum disorders (ASD) is atypical and may vary with age. However, to date, no measures of functional connectivity measured within the first 2 years have specifically associated with a later ASD diagnosis.

Methods

In the present study, we analyzed functional brain connectivity in 14-month-old infants at high and low familial risk for ASD using electroencephalography (EEG). EEG was recorded while infants attended to videos. Connectivity was assessed using debiased weighted phase lag index (dbWPLI). At 36 months, the high-risk infants were assessed for symptoms of ASD.

Results

As a group, high-risk infants who were later diagnosed with ASD demonstrated elevated phase-lagged alpha-range connectivity as compared to both low-risk infants and high-risk infants who did not go on to ASD. Hyper-connectivity was most prominent over frontal and central areas. The degree of hyper-connectivity at 14 months strongly correlated with the severity of restricted and repetitive behaviors in participants with ASD at 3 years. These effects were not attributable to differences in behavior during the EEG session or to differences in spectral power.

Conclusions

The results suggest that early hyper-connectivity in the alpha frequency range is an important feature of the ASD neurophysiological phenotype.

Electronic supplementary material

The online version of this article (doi:10.1186/1866-1955-6-40) contains supplementary material, which is available to authorized users.     

Standards of Scoring,Monitoring, and Parameter Targeting in German Neurocritical Care Units: A National Survey

Background

Optimal management of physiological parameters in neurological/neurosurgical intensive care units (NICUs) is largely unclear as high-quality evidence is lacking. The aim of this survey was to investigate if standards exist in the use of clinical scores, systemic and cerebral monitoring and the targeting of physiology values and in what way this affects clinical management in German NICUs.

Methods

National survey, on-line anonymized questionnaire. German departments stating to run a neurological, neurosurgical or interdisciplinary neurological/neurosurgical intensive care unit were identified by a web-based search of all German hospitals and contacted via email.

Results

Responses from 78 German NICUs were obtained. Of 19 proposed clinical/laboratory/radiological scores only 5 were used regularly by >60 %. Bedside neuromonitoring (NM) predominantly consisted of transcranial Doppler sonography (94 %), electroencephalography (92 %) and measurement of intracranial pressure (ICP) (90 %), and was installed if patients had or were threatened by elevated ICP (86 %), had specific diseases like subarachnoid hemorrhage (51 %) or were comatose (35 %). Although mean trigger values for interventions complied with guidelines or wide-spread customs, individual trigger values varied widely, e.g., for hyperglycemia (maximum blood glucose between 120 and 250 mg/dl) or for anemia (minimum hemoglobin values between 5 and 10 g/dl).

Conclusions

Although apparently aiming for standardization in neurocritical care, German NICUs show substantial differences in NM and monitoring-associated interventions. In terms of scoring and monitoring methods, German NICUs seem to be quite conservative. These survey results suggest a need of prospective and randomized interventional trials in neurocritical care to help define standards and target values.     

Time to epileptiform activity and EEG background recovery are independent predictors after cardiac arrest

Objective

Investigate the temporal development of EEG and prognosis.