Diagnostic yield of electroencephalography in the medical and surgical intensive care unit

Diagnostic Approach to the Patient with Altered Mental Status

Acute encephalopathy is a common presenting symptom in the emergency room and complicates many hospital and intensive care unit admissions. The evaluation of patients with encephalopathy poses several challenges: limited history and examination due to the patient's mental status, broad differential diagnosis of systemic and neurologic etiologies, low yield of neurodiagnostic testing due to the high base rate of systemic causes, and the importance of identifying less common neurologic causes of encephalopathy that can be life-threatening if not identified and treated. This article discusses the differential diagnosis of acute encephalopathy, presents an approach to the history and examination in a patient with encephalopathy, reviews the literature on the yield of neurodiagnostic testing in this population, and provides a diagnostic framework for the evaluation of patients with altered mental status.

The Role of Routine Electroencephalography in the Diagnosis of Seizures in Medical Intensive Care Units

Seizures should be diagnosed and treated to ensure optimal health outcomes in critically ill patients admitted in the medical intensive care unit (MICU). Continuous electroencephalography is still infrequently used in the MICU. We investigated the effectiveness of routine EEG (rEEG) in detecting seizures in the MICU. A total of 560 patients admitted to the MICU between October 2018 and March 2023 and who underwent rEEG were reviewed. Seizure-related rEEG constituted 47% of all rEEG studies. Totally, 39% of the patients experienced clinical seizures during hospitalization; among them, 48% experienced the seizure, and 13% experienced their first seizure after undergoing an rEEG study. Seventy-seven percent of the patients had unfavorable short-term outcomes. Patients with cardiovascular diseases were the most likely to have the suppression/burst suppression (SBS) EEG pattern and the highest mortality rate. The rhythmic and periodic patterns (RPPs) and electrographic seizure (ESz) EEG pattern were associated with seizures within 24 h after rEEG, which was also related to unfavorable outcomes. Significant predictors of death were age > 59 years, the male gender, the presence of cardiovascular disease, a Glasgow Coma Scale score ≤ 5, and the SBS EEG pattern, with a predictive performance of 0.737 for death. rEEG can help identify patients at higher risk of seizures. We recommend repeated rEEG in patients with ESz or RPP EEG patterns to enable a more effective monitoring of seizure activities.

Evaluation of Paroxysmal Events in Critically Ill Patients: Relationship of Primary Diagnosis to Long-Term Electroencephalogram Yield

Continuous EEG (cEEG) is indicated for the workup of paroxysmal events. We aimed to assess whether primary admission diagnoses predict the yield of cEEG when ordered for evaluating paroxysmal events. We identified patients in the ICU who underwent at least 6 hours of cEEG monitoring to evaluate paroxysmal events. Primary admission diagnoses were categorized into neurological or non-neurological conditions. cEEG results were dichotomized into presence or absence of epileptiform discharges. We identified 159 recordings that were obtained for the evaluation of paroxysmal events. Most patients (n = 100, 63%) were admitted with primary admission diagnoses of neurological disorders, such as ischemic stroke, or intracranial hemorrhage. We found that patients with primary neurological conditions were more likely to have brain surgeries, abnormal brain imaging, and focal neurological deficits on examination compared to those with primary non-neurological conditions. However, there was no significant difference in the prevalence of epileptiform discharges in cEEG among patients with primary diagnoses of neurological or non-neurological disorders. These results suggest that cEEG is often necessary to evaluate paroxysmal events, even among patients without primary neurological disorders.

Prevalence of Electrographic Seizures in Hospitalized Patients With Altered Mental Status With No Significant Seizure Risk Factors Who Underwent Continuous EEG Monitoring: A Retrospective Study

OBJECTIVES

The objective of this study is to evaluate the prevalence of electrographic seizures in hospitalized patients with altered mental status and no significant risk factors for seizures.

METHODS

We retrospectively reviewed over a six-year period (2013-2019) the medical records of all adults admitted at Ohio State University Wexner Medical Center (OSUWMC), who underwent continuous electroencephalography (cEEG) monitoring for > 48 hours. Our primary objective was to identify the prevalence of electrographic seizures in patients with altered mental status and no significant acute or remote risk factors for seizures.

RESULTS

A total of 1966 patients were screened for the study, 1892 were excluded (96.2%) and 74 patients met inclusion criteria. Electrographic seizures were identified in seven of 74 patients (9.45%). We found a significant correlation between electrographic seizures and a history of hepatic cirrhosis, n= 4 (57%), (p=0.035), acute chronic hepatic failure during admission, 71% (n=5), (p=0.027), and hyperammonemia (p =0.009).

CONCLUSION

In this retrospective study of patients with altered mental status and no significant acute or remote risk factors for seizures who underwent cEEG monitoring for > 48 hours, electrographic seizures were identified in 9.45%. Electrographic seizures were associated with hepatic dysfunction and hyperammonemia. Based on our results, cEEG monitoring should be considered in patients with altered mental status and hepatic dysfunction even in the absence of other seizure risk factors.

Incidence of Seizure and Associated Risk Factors in Patients in the Medical Intensive Care Unit (ICU) at Memorial Sloan Kettering Cancer Center (MSK) from 2016-2017

Background: Seizures and status epilepticus are common neurologic complications in the intensive care unit (ICU) but the incidence in a cancer ICU is unknown. It is important to understand seizure risk factors in cancer patients to properly diagnose the seizure type to ensure appropriate therapy. Methods: We identified patients admitted to the medical ICU at Memorial Sloan Kettering Cancer Center (MSK) from January 2016 to December 2017 who had continuous or routine electroencephalography (EEG) and identified clinical and electrographic seizures by chart review. Results: Of the 1059 patients admitted to the ICU between 2016 and 2017, 50 patients had clinical and/or electrographic seizures (incidence of 4.7%, 95% CI: 3.4-6.0). The incidences of clinical and electrographic seizure were 4.1% and 1.1%, respectively. In a multivariable stepwise regression model, history of seizure (OR: 2.9, 95% CI: 1.1-7.8, P: .03), brain metastasis (OR: 2.5, 95% CI: 1.1-5.8, P: .03), vasopressor requirement (OR: 2.2, 95% CI: 1.0-4.9, P: .05), and age < 65 (2.4, 95% CI: 1.2-5.0, P: .02) were associated with increased risk of seizure (either clinical or electrographic). Obtaining continuous EEG instead of routine EEG increased the yield of seizure detection significantly (OR: 3.9, 95% CI: 1.3-11.1, P: .01). No chemotherapy in the past 30 days, no antibiotic use, vasopressor requirement, and having a brain tumor increased risk of electrographic seizure. Length of continuous EEG > 24 h significantly increased the chances of both clinical and electrographic seizure detection, (OR: 2.6 [95% CI: 1.2-5.7] and 15.0 [95% CI: 2.7-82.5], respectively). Conclusions: We identified known and cancer-related risk factors which can aid clinicians in diagnosing seizures in cancer ICUs. Long-term video EEG monitoring should be considered, particularly given the treatable and reversible nature of seizures.

Management of Status Epilepticus and Indications for Inpatient Electroencephalography Monitoring

Status epilepticus (SE) is a neurologic emergency requiring immediate time-sensitive treatment to minimize neuronal injury and systemic complications. Minimizing time to administration of first- and second-line therapy is necessary to optimize the chances of successful seizure termination in generalized convulsive SE (GCSE). The approach to refractory and superrefractory GCSE is less well defined. Multiple agents with differing complementary actions that facilitate seizure termination are recommended. Nonconvulsive SE (NCSE) has a wide range of presentations and approaches to treatment. Continuous electroencephalography is critical to the management of both GCSE and NCSE, while its use for patients without seizure continues to expand.

Electroencephalographic Abnormalities are Common in COVID-19 and are Associated with Outcomes

OBJECTIVE

The aim was to determine the prevalence and risk factors for electrographic seizures and other electroencephalographic (EEG) patterns in patients with Coronavirus disease 2019 (COVID-19) undergoing clinically indicated continuous electroencephalogram (cEEG) monitoring and to assess whether EEG findings are associated with outcomes.

METHODS

We identified 197 patients with COVID-19 referred for cEEG at 9 participating centers. Medical records and EEG reports were reviewed retrospectively to determine the incidence of and clinical risk factors for seizures and other epileptiform patterns. Multivariate Cox proportional hazards analysis assessed the relationship between EEG patterns and clinical outcomes.

RESULTS

Electrographic seizures were detected in 19 (9.6%) patients, including nonconvulsive status epilepticus (NCSE) in 11 (5.6%). Epileptiform abnormalities (either ictal or interictal) were present in 96 (48.7%). Preceding clinical seizures during hospitalization were associated with both electrographic seizures (36.4% in those with vs 8.1% in those without prior clinical seizures, odds ratio [OR] 6.51, p = 0.01) and NCSE (27.3% vs 4.3%, OR 8.34, p = 0.01). A pre-existing intracranial lesion on neuroimaging was associated with NCSE (14.3% vs 3.7%; OR 4.33, p = 0.02). In multivariate analysis of outcomes, electrographic seizures were an independent predictor of in-hospital mortality (hazard ratio [HR] 4.07 [1.44-11.51], p < 0.01). In competing risks analysis, hospital length of stay increased in the presence of NCSE (30 day proportion discharged with vs without NCSE: HR 0.21 [0.03-0.33] vs 0.43 [0.36-0.49]).

INTERPRETATION

This multicenter retrospective cohort study demonstrates that seizures and other epileptiform abnormalities are common in patients with COVID-19 undergoing clinically indicated cEEG and are associated with adverse clinical outcomes. ANN NEUROL 2021;89:872-883.

Does continuous electroencephalography influence therapeutic decisions in neurocritical care?

OBJECTIVES

In the neurocritical care unit (neuro-ICU), the impact of continuous EEG (cEEG) on therapeutic decisions and prognostication, including outcome prediction using the Status Epilepticus Severity Score (STESS), is poorly investigated. We studied to what extent cEEG contributes to treatment decisions, and how this relates to clinical outcome and the use of STESS in neurocritical care.

METHODS

We included patients admitted to the neuro-ICU or neurological step-down unit of a tertiary referral hospital between 05/2013 and 06/2015. Inclusion criteria were ≥20 h of cEEG monitoring and age ≥15 years. Exclusion criteria were primary epileptic and post-cardiac arrest encephalopathies.

RESULTS

Ninety-eight patients met inclusion criteria, 80 of which had status epilepticus, including 14 with super-refractory status. Median length of cEEG monitoring was 50 h (range 21-374 h). Mean STESS was lower in patients with favorable outcome 1 year after discharge (modified Rankin Scale [mRS] 0-2) compared to patients with unfavorable outcome (mRS 3-6), albeit not statistically significant (mean STESS 2.3 ± 2.1 vs 3.6 ± 1.7, p = 0.09). STESS had a sensitivity of 80%, a specificity of 42%, and a negative predictive value of 93% for outcome. cEEG results changed treatment decisions in 76 patients, including escalation of antiepileptic treatment in 65 and reduction in 11 patients.

CONCLUSION

Status Epilepticus Severity Score had a high negative predictive value but low sensitivity, suggesting that STESS should be used cautiously. Of note, cEEG results altered clinical decision-making in three of four patients, irrespective of the presence or absence of status epilepticus, confirming the clinical value of cEEG in neurocritical care.

Randomized trial of lacosamide versus fosphenytoin for nonconvulsive seizures

OBJECTIVE

The optimal treatment of nonconvulsive seizures in critically ill patients is uncertain. We evaluated the comparative effectiveness of the antiseizure drugs lacosamide (LCM) and fosphenytoin (fPHT) in this population.

METHODS

The TRENdS (Treatment of Recurrent Electrographic Nonconvulsive Seizures) study was a noninferiority, prospective, multicenter, randomized treatment trial of patients diagnosed with nonconvulsive seizures (NCSs) by continuous electroencephalography (cEEG). Treatment was randomized to intravenous (IV) LCM 400mg or IV fPHT 20mg phenytoin equivalents/kg. The primary endpoint was absence of electrographic seizures for 24 hours as determined by 1 blinded EEG reviewer. The frequency with which NCS control was achieved in each arm was compared, and the 90% confidence interval (CI) was determined. Noninferiority of LCM to fPHT was to be concluded if the lower bound of the CI for relative risk was >0.8.

RESULTS

Seventy-four subjects were enrolled (37 LCM, 37 fPHT) between August 21, 2012 and December 20, 2013. The mean age was 63.6 years; 38 were women. Seizures were controlled in 19 of 30 (63.3%) subjects in the LCM arm and 16 of 32 (50%) subjects in the fPHT arm. LCM was noninferior to fPHT (p = 0.02), with a risk ratio of 1.27 (90% CI = 0.88-1.83). Treatment emergent adverse events (TEAEs) were similar in both arms, occurring in 9 of 35 (25.7%) LCM and 9 of 37 (24.3%) fPHT subjects (p = 1.0).

INTERPRETATION

LCM was noninferior to fPHT in controlling NCS, and TEAEs were comparable. LCM can be considered an alternative to fPHT in the treatment of NCSs detected on cEEG. Ann Neurol 2018;83:1174-1185.

A phase I trial of low-dose inhaled carbon monoxide in sepsis-induced ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a prevalent disease with significant mortality for which no effective pharmacologic therapy exists. Low-dose inhaled carbon monoxide (iCO) confers cytoprotection in preclinical models of sepsis and ARDS.

METHODS

We conducted a phase I dose escalation trial to assess feasibility and safety of low-dose iCO administration in patients with sepsis-induced ARDS. Twelve participants were randomized to iCO or placebo air 2:1 in two cohorts. Four subjects each were administered iCO (100 ppm in cohort 1 or 200 ppm in cohort 2) or placebo for 90 minutes for up to 5 consecutive days. Primary outcomes included the incidence of carboxyhemoglobin (COHb) level ≥10%, prespecified administration-associated adverse events (AEs), and severe adverse events (SAEs). Secondary endpoints included the accuracy of the Coburn-Forster-Kane (CFK) equation to predict COHb levels, biomarker levels, and clinical outcomes.

RESULTS

No participants exceeded a COHb level of 10%, and there were no administration-associated AEs or study-related SAEs. CO-treated participants had a significant increase in COHb (3.48% ± 0.7% [cohort 1]; 4.9% ± 0.28% [cohort 2]) compared with placebo-treated subjects (1.97% ± 0.39%). The CFK equation was highly accurate at predicting COHb levels, particularly in cohort 2 (R2 = 0.9205; P < 0.0001). Circulating mitochondrial DNA levels were reduced in iCO-treated participants compared with placebo-treated subjects.

CONCLUSION

Precise administration of low-dose iCO is feasible, well-tolerated, and appears to be safe in patients with sepsis-induced ARDS. Excellent agreement between predicted and observed COHb should ensure that COHb levels remain in the target range during future efficacy trials.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02425579.

FUNDING

NIH grants P01HL108801, KL2TR002385, K08HL130557, and K08GM102695.

New Developments in Refractory Status Epilepticus

Status epilepticus (SE) is a medical emergency and presents with either a continuous prolonged seizure or multiple seizures without full recovery of consciousness in between them. The goals of treatment are prompt recognition, early seizure termination, and simultaneous evaluation for any potentially treatable cause. Improved understanding of the pathophysiology has led to a more practical definition. New data have emerged regarding the safety and efficacy of alternative agents, which are increasingly used in the management of these patients. Continuous electroencephalogram monitoring is more widely used and has revealed a higher incidence of subclinical seizures than was previously thought.

Frequency of post-stroke electroencephalographic epileptiform activity - a systematic review and meta-analysis of observational studies

INTRODUCTION

Cerebrovascular diseases are the most frequent risk factor for epilepsy in the elderly, and epileptic phenomenon following stroke is known to worsen the prognosis. Although electroencephalography is the gold standard epilepsy biomarker, it is rarely used in post-stroke studies, and the frequency of post-stroke epileptiform activity is still uncertain.

PATIENTS AND METHODS

We analysed studies indexed to MEDLINE, Embase, Web of Science, PsycINFO and OpenGrey (up to March 2015), reporting post-stroke electroencephalographic epileptiform activity frequency in adults. Epileptiform activity was classified as ictal (electrographic seizures) and interictal (non-periodic spikes and sharp waves). Data selection, extraction and appraisal were done in duplicate. Random-effects meta-analysis was used to pool frequencies.

RESULTS

The pooled frequency of post-stroke ictal and interictal epileptiform activity was 7% (95% CI 3%-12%) and 8% (95% CI 4%-13%), respectively. The use of continuous electroencephalogram was not associated with an increased frequency of electrographic seizures (p = 0.05), nor did the management setting (Intensive Care Unit versus non- Intensive Care Unit, p = 0.31). However, studies with continuous electroencephalogram showed a higher frequency of interictal epileptiform activity (p = 0.01).

DISCUSSION

This study provides the best available estimates of the frequency of post-stroke electroencephalographic epileptiform activity. Due to detection bias, it was not possible to correlate clinical and electrographic seizures.

CONCLUSION

The frequency of ictal and interictal epileptiform activity in the electroencephalogram was comparable with previous frequency analyses of clinical seizures. The frequency of ictal epileptiform activity did not change with continuous record or clinical setting, while the frequency of interictal epileptiform activity increased with continuous record.

The Relationship of Triphasic Waves with Intracranial Pressure as a Possible Prognostic Marker in Traumatic Brain Injury

Background

Continuous electroencephalography (CEEG) monitoring is used for detection of convulsive and nonconvulsive seizures and assessing the degree of encephalopathy in critically ill patients. A commonly seen encephalopathic pattern on CEEG is generalized periodic discharges with triphasic wave (TW) morphology. The underlying role and prognostic significance of TW in relationship to intracranial pressure (ICP) remain unknown. We present a case highlighting the relationship of TW with ICP in a case with severe traumatic brain injury (TBI).

Method

Case report.

Results

A patient with severe TBI and no underlying metabolic abnormalities was admitted to the neurocritical care unit. TW were seen on CEEG. The TW diminished during episodes of intracranial hypertension but reappeared with reduction of the intracranial pressure.

Conclusion

This study highlights a possible favorable prognostic marker of finding TW in a patient with intracranial hypertension. We have proposed a preliminary understanding of the relationship between TW and intracranial hypertension, which may be helpful in formulating future studies involving larger cohorts.

New Developments in Refractory Status Epilepticus

Status epilepticus (SE) is a medical emergency and presents with either a continuous prolonged seizure or multiple seizures without full recovery of consciousness in between them. The goals of treatment are prompt recognition, early seizure termination, and simultaneous evaluation for any potentially treatable cause. Improved understanding of the pathophysiology has led to a more practical definition. New data have emerged regarding the safety and efficacy of alternative agents, which are increasingly used in the management of these patients. Continuous electroencephalogram monitoring is more widely used and has revealed a higher incidence of subclinical seizures than was previously thought.

Neurologic complications of polytrauma

Neurologic complications in polytrauma can be classified by etiology and clinical manifestations: neurovascular, delirium, and spinal or neuromuscular problems. Neurovascular complications include ischemic strokes, intracranial hemorrhage, or the development of traumatic arteriovenous fistulae. Delirium and encephalopathy have a reported incidence of 67-92% in mechanically ventilated polytrauma patients. Causes include sedation, analgesia/pain, medications, sleep deprivation, postoperative state, toxic ingestions, withdrawal syndromes, organ system dysfunction, electrolyte/metabolic abnormalities, and infections. Rapid identification and treatment of the underlying cause are imperative. Benzodiazepines increase the risk of delirium, and alternative agents are preferred sedatives. Pharmacologic treatment of agitated delirium can be achieved with antipsychotics. Nonconvulsive seizures and status epilepticus are not uncommon in surgical/trauma intensive care unit (ICU) patients, require electroencephalography for diagnosis, and need timely management. Spinal cord ischemia is a known complication in patients with traumatic aortic dissections or blunt aortic injury requiring surgery. Thoracic endovascular aortic repair has reduced the paralysis rate. Neuromuscular complications include nerve and plexus injuries, and ICU-acquired weakness. In polytrauma, the neurologic examination is often confounded by pain, sedation, mechanical ventilation, and distracting injuries. Regular sedation pauses for examination and maintaining a high index of suspicion for neurologic complications are warranted, particularly because early diagnosis and management can improve outcomes.

Seizures and the Role of Anticonvulsants After Traumatic Brain Injury

Posttraumatic seizures are a common complication of traumatic brain injury. Posttraumatic epilepsy accounts for 20% of symptomatic epilepsy in the general population and 5% of all epilepsy. Early posttraumatic seizures occur in more than 20% of patients in the intensive care unit and are associated with secondary brain injury and worse patient outcomes. Most posttraumatic seizures are nonconvulsive and therefore continuous electroencephalography monitoring should be the standard of care for patients with moderate or severe brain injury. The literature shows that posttraumatic seizures result in secondary brain injury caused by increased intracranial pressure, cerebral edema and metabolic crisis.

Neurologic complications of sepsis

Over the past decades, the incidence of sepsis and resultant neurologic sequelae has increased, both in industrialized and low- or middle-income countries, by approximately 5% per year. Up to 300 patients per 100 000 population per year are reported to suffer from sepsis, severe sepsis, and septic shock. Mortality is up to 30%, depending on the precision of diagnostic criteria. The increasing incidence of sepsis is partially explained by demographic changes in society, with aging, increasing numbers of immunocompromised patients, dissemination of multiresistant pathogens, and greater availability of supportive medical care in both industrialized and middle-income countries. This results in more septic patients being admitted to intensive care units. Septic encephalopathy is a manifestation especially of severe sepsis and septic shock where the neurologist plays a crucial role in diagnosis and management. It is well known that timely treatment of sepsis improves outcome and that septic encephalopathy may precede other signs and symptoms. Particularly in the elderly and immunocompromised patient, the brain may be the first organ to show signs of failure. The neurologist diagnosing early septic encephalopathy may therefore contribute to the optimal management of septic patients. The brain is not only an organ failing in sepsis (a "sepsis victim" - as with other organs), but it also overwhelmingly influences all inflammatory processes on a variety of pathophysiologic levels, thus contributing to the initiation and propagation of septic processes. Therefore, the best possible pathophysiologic understanding of septic encephalopathy is essential for its management, and the earliest possible therapy is crucial to prevent the evolution of septic encephalopathy, brain failure, and poor prognosis.

Electrophysiologic monitoring in acute brain injury

To determine the optimal use and indications of electroencephalography (EEG) in critical care management of acute brain injury (ABI). An electronic literature search was conducted for articles in English describing electrophysiological monitoring in ABI from January 1990 to August 2013. A total of 165 studies were included. EEG is a useful monitor for seizure and ischemia detection. There is a well-described role for EEG in convulsive status epilepticus and cardiac arrest (CA). Data suggest EEG should be considered in all patients with ABI and unexplained and persistent altered consciousness and in comatose intensive care unit (ICU) patients without an acute primary brain condition who have an unexplained impairment of mental status. There remain uncertainties about certain technical details, e.g., the minimum duration of EEG studies, the montage, and electrodes. Data obtained from both EEG and EP studies may help estimate prognosis in ABI patients, particularly following CA and traumatic brain injury. Data supporting these recommendations is sparse, and high quality studies are needed. EEG is used to monitor and detect seizures and ischemia in ICU patients and indications for EEG are clear for certain disease states, however, uncertainty remains on other applications.

Automatic detection of rhythmic and periodic patterns in critical care EEG based on American Clinical Neurophysiology Society (ACNS) standardized terminology

AIMS OF THE STUDY

Continuous EEG from critical care patients needs to be evaluated time efficiently to maximize the treatment effect. A computational method will be presented that detects rhythmic and periodic patterns according to the critical care EEG terminology (CCET) of the American Clinical Neurophysiology Society (ACNS). The aim is to show that these detected patterns support EEG experts in writing neurophysiological reports.

MATERIALS AND METHODS

First of all, three case reports exemplify the evaluation procedure using graphically presented detections. Second, 187 hours of EEG from 10 critical care patients were used in a comparative trial study. For each patient the result of a review session using the EEG and the visualized pattern detections was compared to the original neurophysiology report.

RESULTS

In three out of five patients with reported seizures, all seizures were reported correctly. In two patients, several subtle clinical seizures with unclear EEG correlation were missed. Lateralized periodic patterns (LPD) were correctly found in 2/2 patients and EEG slowing was correctly found in 7/9 patients. In 8/10 patients, additional EEG features were found including LPDs, EEG slowing, and seizures.

CONCLUSION

The use of automatic pattern detection will assist in review of EEG and increase efficiency. The implementation of bedside surveillance devices using our detection algorithm appears to be feasible and remains to be confirmed in further multicenter studies.

Status epilepticus in adults

Status epilepticus is a common neurological emergency with considerable associated health-care costs, morbidity, and mortality. The definition of status epilepticus as a prolonged seizure or a series of seizures with incomplete return to baseline is under reconsideration in an effort to establish a more practical definition to guide management. Clinical research has focused on early seizure termination in the prehospital setting. The approach of early escalation to anaesthetic agents for refractory generalised convulsive status epilepticus, rather than additional trials of second-line anti-epileptic drugs, to avoid neuronal injury and pharmaco-resistance associated with prolonged seizures is gaining momentum. Status epilepticus is also increasingly identified in the inpatient setting as the use of extended electroencephalography monitoring becomes more commonplace. Substantial further research to enable early identification of status epilepticus and efficacy of anti-epileptic drugs will be important to improve outcomes.

Acute brain failure in severe sepsis: a prospective study in the medical intensive care unit utilizing continuous EEG monitoring

PURPOSE

Investigate the prevalence, risk factors and impact of continuous EEG (cEEG) abnormalities on mortality through the 1-year follow-up period in patients with severe sepsis.

METHODS

Prospective, single-center, observational study of consecutive patients admitted with severe sepsis to the Medical ICU at an academic medical center.

RESULTS

A total of 98 patients with 100 episodes of severe sepsis were included; 49 patients (50%) were female, median age was 60 (IQR 52-74), the median non-neuro APACHE II score was 23.5 (IQR 18-28) and median non-neuro SOFA score was 8 (IQR 6-11). Twenty-five episodes had periodic discharges (PD), of which 11 had nonconvulsive seizures (NCS). No patient had NCS without PD. Prior neurological history was associated with a higher risk of PD or NCS (45 vs. 17%; CI 1.53-10.43), while the non-neuro APACHE II, non-neuro SOFA, severity of cardiovascular shock and presence of sedation during cEEG were associated with a lower risk of PD or NCS. Clinical seizures before cEEG were associated with a higher risk of nonconvulsive status epilepticus (24 vs. 6%; CI 1.42-19.94) while the non-neuro APACHE II and non-neuro SOFA scores were associated with a lower risk. Lack of EEG reactivity was present in 28% of episodes. In the survival analysis, a lack of EEG reactivity was associated with higher 1-year mortality [mean survival time 3.3 (95% CI 1.8-4.9) vs. 7.5 (6.4-8.7) months; p = 0.002] but the presence of PD or NCS was not [mean survival time 3.3 (95% CI 1.8-4.9) vs. 7.5 (6.4-8.7) months; p = 0.592]. Lack of reactivity was more frequent in patients on continuous sedation during cEEG. In patients with available 1-year data (34% of the episodes), 82% had good functional outcome (mRS ≤ 3, n = 27). There were no significant predictors of functional outcome, late cognition, and no patient with complete follow-up data developed late seizure or new epilepsy.

CONCLUSIONS

NCS and PD are common in patients with severe sepsis and altered mental status. They were less frequent among the most severely sick patients and were not associated with outcome in this study. Lack of EEG reactivity was more frequent in patients on continuous sedation and was associated with mortality up to 1 year after discharge. Larger studies are needed to confirm these findings in a broader population and to further evaluate long-term cognitive outcome, risk of late seizure and epilepsy.

Continuous electroencephalography in a surgical intensive care unit

PURPOSE

Our aim was to investigate the prevalence, risk factors, and impact on outcome of nonconvulsive seizures (NCSz), nonconvulsive status epilepticus (NCSE), and periodic epileptiform discharges (PEDs) in surgical intensive care unit (SICU) patients with continuous electroencephalography (cEEG) monitoring.

METHODS

This was a retrospective study of SICU patients who underwent cEEG monitoring for altered mental status over a 6-year period. We report the frequency of NCSz (including NCSE) and PEDs on cEEG. The primary outcome was death or severe disability at hospital discharge. Multivariable logistic regression was used to identify whether NCSz (including NCSE) and PEDs were independently associated with poor outcome (death, vegetative state or severe disability).

RESULTS

Of 154 patients, the mean age was 64 ± 14 years old, and 40% were women. The majority of patients were admitted following abdominal surgery (36%) and liver transplantation (24%). Sepsis developed in 100 (65%) patients. Sixteen percent (n = 24) had NCSz [including 5% (N = 8) with NCSE], and 29% (N = 45) had PEDs. All eight patients with NCSE were septic. Clinical seizures prior to cEEG and coma were more common among patients who developed NCSz or NCSE compared to patients without NCSz or NCSE (70 vs. 27%; p < 0.01; 75 vs. 52%; p = 0.046 and 63 vs. 34%; p = 0.09, respectively). NCSzs (including NCSE) were independently associated with poor outcome (20 vs. 3%, OR 10.4, 95% CI 1.0-53.7; p = 0.039).

CONCLUSION

In this retrospective study of SICU patients with cEEG monitoring for altered mental status, NCSz and periodic discharges were frequent and NCSz were independently associated with poor outcome. NCSz were more common when clinical seizures occurred before cEEG.

Continuous and routine EEG in intensive care: utilization and outcomes, United States 2005-2009

OBJECTIVES

To evaluate the effect of intensive care unit continuous EEG (cEEG) monitoring on inpatient mortality, hospital charges, and length of stay.

METHODS

A retrospective cross-sectional study was conducted using the Nationwide Inpatient Sample, a dataset representing 20% of inpatient discharges in nonfederal US hospitals. Adult discharge records reporting mechanical ventilation and EEG (routine EEG or cEEG) were included. cEEG was compared with routine EEG alone in association with the primary outcome of in-hospital mortality and secondary outcomes of total hospital charges and length of stay. Demographics, hospital characteristics, and medical comorbidity were used for multivariate adjustments of the primary and secondary outcomes.

RESULTS

A total of 40,945 patient discharges in the weighted sample met inclusion criteria, of which 5,949 had reported cEEG. Mechanically ventilated patients receiving cEEG were younger than routine EEG patients (56 vs 61 years; p < 0.001). There was no difference in the 2 groups in income or medical comorbidities. cEEG was significantly associated with lower in-hospital mortality in both univariate (odds ratio = 0.54, 95% confidence interval 0.45-0.64; p < 0.001) and multivariate (odds ratio = 0.63, 95% confidence interval 0.51-0.76; p < 0.001) analyses. There was no significant difference in costs or length of stay for patients who received cEEG relative to those receiving only routine EEG. Sensitivity analysis showed that adjusting for diagnosis-related groups (DRGs) for any neurologic diagnoses, DRGs for neurologic procedures, and specific DRGs for epilepsy/convulsions did not substantially alter the association of cEEG with reduced inpatient mortality.

CONCLUSIONS

cEEG is favorably associated with inpatient survival in mechanically ventilated patients, without adding significant charges to the hospital stay.

Diagnostic yield of electroencephalography in a general inpatient population

OBJECTIVE

To determine the frequency and clinical predictors of seizures and markers of epileptiform activity in a noncritically ill general inpatient population.

PATIENTS AND METHODS

We performed a retrospective cohort study of patients 18 years and older who underwent inpatient electroencephalography (EEG) between January 1, 2005, and December 31, 2010, for an indication of spells or altered mental status. The EEGs and reports were reviewed for ictal activity, interictal epileptiform abnormalities, and nonepileptiform abnormalities. Demographic and clinical data were gathered from the electronic medical record to determine seizure predictors.

RESULTS

Of 2235 patients screened, 1048 met the inclusion criteria, of which 825 (78.7%) had an abnormal EEG finding. Seizures occurred in 78 of 1048 patients (7.4%), and interictal epileptiform discharges were noted in 194 of 1048 patients (18.5%). An intracranial mass and spells as the indication for the EEG were independently associated with the group of patients experiencing seizures in a multivariate logistic regression model (adjusted for age, sex, EEG indication, intracranial mass, stroke, and history of epilepsy). Ninety-seven percent of patients (69 of 71) experienced their first seizure within 24 hours of monitoring, and the presence of seizures was associated with a lower likelihood of being discharged (odds ratio, 0.45; 95% CI, 0.27-0.76).

CONCLUSION

Seizures occurred at a high frequency in hospitalized patients with spells and altered mental status. The EEG may be an underused investigative tool in the hospital with the potential to identify treatable causes of these common disorders.

Diagnostic yield of electroencephalography in a general inpatient population

OBJECTIVE

To determine the frequency and clinical predictors of seizures and markers of epileptiform activity in a non-critically ill general inpatient population.

PATIENTS AND METHODS

We performed a retrospective cohort study of patients 18 years and older who underwent inpatient electroencephalography (EEG) between January 1, 2005, and December 31, 2010, for an indication of spells or altered mental status. The EEGs and reports were reviewed for ictal activity, interictal epileptiform abnormalities, and nonepileptiform abnormalities. Demographic and clinical data were gathered from the electronic medical record to determine seizure predictors.

RESULTS

Of 2235 patients screened, 1048 met the inclusion criteria, of which 825 (78.7%) had an abnormal EEG finding. Seizures occurred in 78 of 1048 patients (7.4%), and interictal epileptiform discharges were noted in 194 of 1048 patients (18.5%). An intracranial mass and spells as the indication for the EEG were independently associated with the group of patients experiencing seizures in a multivariate logistic regression model (adjusted for age, sex, EEG indication, intracranial mass, stroke, and history of epilepsy). Ninety-seven percent of patients (69 of 71) experienced their first seizure within 24 hours of monitoring, and the presence of seizures was associated with a lower likelihood of being discharged (odds ratio, 0.45; 95% CI, 0.27-0.76).

CONCLUSION

Seizures occurred at a high frequency in hospitalized patients with spells and altered mental status. The EEG may be an underused investigative tool in the hospital with the potential to identify treatable causes of these common disorders.