EEG Monitoring in the Intensive Care Unit

Case Report: Triphasic Waves in a 9-Year-Old Girl With Anti-NMDAR Encephalitis

BACKGROUND

Triphasic waves (TWs) are mainly described in association with metabolic encephalopathy, especially hepatic encephalopathy. Now, as different conditions including non-metabolic and structural abnormalities have been reported to be associated with TWs, the presence of TWs becomes a non-specific finding for metabolic encephalopathy.

CASE PRESENTATION

We report the first case of anti-NMDAR encephalitis in a 9-year-old girl presenting with TWs on EEG. The TWs background EEG lasted for about 12 h on the 40th day of the disease course. No epileptic wave was found during a series of EEG examinations. The child was discharged from the hospital and no neurological sequelae remained after a six-month follow-up.

CONCLUSIONS

TWs are not specific to metabolic encephalopathy, but can also occur in children with autoimmune encephalitis. This case achieved a good prognosis after the early initiation of immunotherapy.

Prescription patterns for routine EEG ordering in patients with intracranial hemorrhage admitted to a neurointensive care unit

PURPOSE

To examine clinical factors, including established electroencephalography (EEG) consensus recommendations, that may influence EEG-prescription in critically-ill intracerebral hemorrhage (ICH) patients in the neurointensive care unit.

METHODS

Retrospective analysis of 330 ICH patients admitted to a neurointensive care unit at an academic medical center between 01/2013-12/2015. We compared EEG prescription patterns with current EEG consensus recommendations, and employed univariate and multivariable logistic regression modeling to determine clinical variables associated with EEG ordering.

RESULTS

Seventy-eight (41%) of 190 subjects underwent EEG in accordance with EEG-consensus guidelines, demonstrating an overall accuracy (probability that EEG prescription aligned with EEG consensus recommendations) of 64.6% (95%-CI59.1-69.7). Factors independently associated with EEG ordering included fulfillment of EEG consensus recommendations, lower admission Glasgow Coma Scale (GCS), and presence of clinical seizures. The unadjusted and adjusted C-statistics for fulfillment of consensus recommendations was 0.74 (95%-CI 0.69-0.80) and 0.85 (95%-CI 0.81-0.90), respectively. Among 83 subjects undergoing EEG (25.2%), EEG findings informed clinical decision-making in 50 patients (60%).

CONCLUSIONS

EEG appeared underused in ICH, since <50% of patients who fulfilled guideline criteria underwent EEG. Prescription of EEG was related to factors beyond those included in consensus recommendations. Validation of our findings and their association with outcome is required.

EEG for Diagnosis and Prognosis of Acute Nonhypoxic Encephalopathy: History and Current Evidence

The term encephalopathy encompasses a wide variety of complex syndromes caused by a large number of different toxic, metabolic, infectious, and degenerative derangements. Acute encephalopathy typically presents with a fluctuating course involving alteration of mental status or confusion and decreased (or rarely increased) motor activity. There usually are lethargy, cognitive impairment, altered memory and mental processing of information, and disturbed sleep-wake cycles. Encephalopathy mainly occurs in the elderly and is frequently encountered in intensive care units and postoperatively. Despite new diagnostic procedures and advances in intensive medical care, acute encephalopathy constitutes a significant cause of morbidity and mortality in hospitalized patients. EEG enables rapid bedside electrophysiological monitoring providing dynamic real-time information on neocortical brain activity and dysfunction. Hence, EEG complements clinical and neuroimaging assessments of encephalopathic patients. Progressive slowing of EEG background activity with increasing cerebral compromise, the emergence of episodic electrographic transients, seizures, and decreased EEG reactivity to external stimuli provide important diagnostic and prognostic information. The aim of this review was to provide a comprehensive overview of the current evidence for the diagnostic and prognostic value of EEG in adult intensive care unit patients with acute nonhypoxic encephalopathy.

Clinical and electroencephalographic correlates of acute encephalopathy

The term encephalopathy encompasses a wide variety of syndromes caused by a large number of different toxic, metabolic, and degenerative derangements. Despite advances in intensive medical care and new diagnostic procedures, encephalopathy remains a frequent and underrecognized critical medical condition with high morbidity and mortality. Electroencephalography (EEG) enables rapid bedside electrophysiological measurements of brain dysfunction and complements clinical and neuroimaging assessment of encephalopathic patients. Both progressive slowing of EEG background activity with increasing cerebral compromise and decreased EEG reactivity to external stimuli provide important diagnostic and prognostic information. The aim of this review was to provide an overview of the diagnostic and prognostic value of EEG in encephalopathic patients.

Continuous electroencephalographic monitoring in critically ill patients: indications, limitations, and strategies

OBJECTIVE

Continuous electroencephalography as a bedside monitor of cerebral activity has been used in a range of critically ill patients. This review compiles the indications, limitations, and strategies for continuous electroencephalography in the ICU.

DATA SOURCE

The authors searched the electronic MEDLINE database.

STUDY SELECTION AND DATA EXTRACTION

References from articles of special interest were selected.

DATA SYNTHESIS AND CONCLUSION

Electroencephalographically-defined suppression is routinely used as the basis for titration of pharmacologic therapy in refractory status epilepticus and intracranial hypertension. The increasing use of continuous electroencephalography reveals a clinically underappreciated burden of epileptiform and epileptic activity in patients with primary acute neurologic disorders, and also in critically ill patients with acquired encephalopathy. Status epilepticus is reported with continuous electroencephalography in 1% to 10% of patients with ischemic stroke, 8% to 14% with traumatic brain injury, 10% to 14% with subarachnoid hemorrhage, 1% to 21% with intracerebral hemorrhage, and 30% of patients following cardiorespiratory arrest. These figures underscore the importance of continuous electroencephalography in the critically ill. The interpretation of continuous electroencephalography in the ICU is challenged by electroencephalography artifacts and the frequent subtle differences between ictal and interictal patterns.

Status epilepticus: a review, with emphasis on refractory cases

Status epilepticus is among the most dramatic of clinical presentations encountered by emergency room physicians, neurologists, neurosurgeons and intensivists. While progress in its management has been aided significantly with an increasing number of effective treatment options, improved diagnostic methods and more effective monitoring, poor outcomes and diagnostic failures are still frequently encountered. Refractory cases still carry significant morbidity and mortality rates, including poor cognitive outcomes. This review discusses basic pathophysiology and management of status epilepticus, neuroimaging findings, the role of continuous electroencephalogram monitoring and nonconvulsive status epilepticusas well as recent developments in treatment options for refractory cases.

Generalized periodic epileptiform discharges in critically ill children: a continuum of status epilepticus or an epiphenomenon?

PURPOSE

Generalized periodic epileptiform discharges (GPEDs) are a specific periodic EEG pattern, reported with status epilepticus (SE) or a metabolic or an anoxic encephalopathy in critically ill patients. In this study, we examined the clinical course and evolution of EEG findings associated with GPEDs in children with refractory convulsive SE.

METHODS

The EEG reports of 279 children with SE diagnosed between 2002 and 2010 were reviewed to detect GPEDs. Ten children were identified with GPEDs on continuous EEG recording. The entire EEG recording was available for review in only six children. In the clinical course, seizure characteristics and evolution of EEG findings were analyzed.

RESULTS

Six children (age, 5 to 17 years) were admitted to the intensive care unit with refractory convulsive SE. All had acute symptomatic SE except for one child with a history of epilepsy and developmental delay. Intravenous anesthetic agents were used to treat convulsive SE in five children. After tapering the intravenous anesthetic agents, GPEDs were seen on the continuous EEG recording, nonconvulsive seizures occurred in five, and nonconvulsive SE in four children. None of the children returned to baseline, and three children died.

CONCLUSIONS

Generalized periodic epileptiform discharges are seen during the treatment course of convulsive SE in children and heralded seizure recurrence. We found a sequential evolution of the EEG patterns after the control of convulsive SE, with GPEDs occurring in a dynamic fashion in a continuum along with burst suppression and electrographic seizures. Recognizing that GPEDs represent a still active epileptic state after the control of convulsive SE with intravenous anesthetic agents and modifying the treatment regimen to control GPEDs may prevent immediate seizure recurrence.

Alpha coma pattern in a child

Alpha coma, an EEG pattern characterized by diffuse or widespread rhythmic activity in the alpha frequency band, is typically recorded in patients with profound coma and is frequently associated with severe neurological conditions. The most common etiologic factors of this pattern are hypoxic-ischemic encephalopathy, encephalitis, head trauma, metabolic disorders, and drug overdose. Reports of alpha coma pattern in children are relatively common. Clinical significance, both in children and adults, is variable, and highly dependent on etiology. The objective of this article is to report a clinical case of alpha coma pattern in a child with neuroblastoma. The EEG pattern was recorded during the evolution of treatment, secondary to complicating septic encephalopathy. The alpha coma pattern was replaced by a normal trace following a favorable outcome after sepsis resolution.