The following is from Resource (1), Management of Status Epilepticus in Children:
Consideration should also be given to performing continuous electroencephalogram (EEG) monitoring. The Neurocritical Care Society’s guideline stipulates that EEG monitoring should be initiated 15–60 min after seizure onset to evaluate for non-convulsive status epilepticus for patients who are not returning to baseline within 10 min of convulsive seizure cessation or within 60 min for patients in whom ongoing seizures are suspected. . . . A consensus statement from the American Clinical Neurophysiology Society regarding EEG monitoring in critically ill adults and children recommends written plans for EEG monitoring (including indications, urgency, and duration), obtaining time-locked video, and EEG monitoring review at least twice per day. The consensus statement provides EEG monitoring indications which include: (1) persistently altered mental status after convulsive status epilepticus or seizures terminate; (2) acute supratentorial brain injury (including intraparenchymal hemorrhage, moderate-severe
traumatic brain injury, central nervous system infections, recent neurosurgical procedures, brain tumors, acute ischemic stroke, hypoxic-ischemic encephalopathy, sepsis associated encephalopathy, extracorporeal membrane oxygenation) with altered mental status; (3) fluctuating or unexplained alteration in mental status; (4) routine EEG with periodic discharges; (5) pharmacologic paralysis and risk for seizures; or (6) paroxysmal events suspected to be seizures. The consensus statement recommends EEG monitoring for 24 h, the entire duration of pharmacologic coma induction for seizure
management, and for 24 h after pharmacologic coma drugs weaned [37,38]. Additionally, urgent EEG may be indicated when non-epileptic seizures are suspected (e.g., psychogenic status epilepticus), as the appropriate diagnosis may avoid further administration of unnecessary anti-seizure medications.
The following is from Resource (2), Consensus statement on continuous EEG in critically ill adults and children, part I: indications:
I. INTRODUCTION AND PURPOSE
Critically ill patients are at high risk for a variety of neurologic insults, including seizures, ischemia, edema, infection, and increased intracranial pressure, which can result in permanent neurologic disability if untreated. Despite these risks, there are few techniques for continuously monitoring brain function. Electroencephalography (EEG) measures the brain’s electrical activity, can be recorded continuously at the bedside, has good spatial and excellent temporal resolution, and is sensitive to changes in both brain structure and function (Nuwer 1994). Over the past decade, technical advances have improved the efficiency of continuous EEG (CEEG) recording and remote review, leading to a greater than four-fold increase in the number of CEEGs performed in intensive care units (ICUs) (Ney, van der Goes et al. 2013). Recent surveys, however, show variability in why and how CEEG is performed in the ICU (Abend, Dlugos et al. 2010, Sanchez, Arndt et al. 2013, Gavvala,
Abend et al. 2014), highlighting the need for clinical guidance on this expensive and labor intensive procedure.
Critical care continuous EEG (CCEEG) refers to the simultaneous recording of EEG and clinical behavior (video) over extended time periods (hours to weeks) in critically ill patients at risk for secondary brain injury and neurologic deterioration. CCEEG is usually performed in an ICU setting, but this varies by hospital and some patients may be in step-down units or general medical or surgical units. CCEEG typically includes simultaneous video recording, and may include graphical displays of quantitative EEG trends (QEEG). The goal of CCEEG is to identify changes in brain function, such as nonconvulsive seizures (NCS) or ischemia, which may not be evident by neurological examination alone, in order to facilitate
early identification and management of these abnormalities.
The ACNS CCEEG Guidelines Committee describes a variety of models for CCEEG. Some techniques are available in only a few specialized centers and represent an “idealized” system for CCEEG. The committee recognizes that many CCEEG programs do not have full access to all equipment, technical staff, and interpreting staff described below, but should use these recommendations as a guide for program development and improvement. Each center should provide CCEEG at the highest level that local resources allow. Transferring patients to more specialized centers should be considered when local resources are insufficient for patient care needs and when the advantages of CCEEG outweigh the potential risks of transfer. CCEEG is often requested as an urgent or emergency study in critically ill patients. Current staffing models may not support 24-hour 7-day per week inhouse NDTs. This consensus statement therefore addresses minimum techniques for CCEEG under emergency circumstances, as well as optimal techniques when qualified
NDTs are available.
CCEEG is a rapidly evolving technology, and this statement addresses only current consensus-based recommendations for CCEEG. At this time, there is inadequate data on the impact of CCEEG on clinical outcomes to develop practice standards based on strong evidence, but existing evidence is summarized within this document. Because NCS and other secondary brain injuries are often completely unrecognized without CCEEG, this
document emphasizes that delayed recognition is better than no recognition. In particular, the term “monitoring” usually does not imply continuous real time analysis and reporting of
the EEG. Due to resource limitations, CCEEG is typically acquired continuously and reviewed intermittently by neurodiagnostic technologists (NDTs) for technical quality and
changes in EEG patterns and also intermittently by electroencephalographers for interpretation and clinical correlation. The decision to initiate CCEEG, frequency of review,
and communication of results to ICU caregivers are determined by local resources, local monitoring indications, CCEEG findings, and the patient’s clinical status.
III. INDICATIONS FOR CCEEG
A. Diagnosis of Nonconvulsive Seizures (NCS), Nonconvulsive Status Epilepticus (NCSE), and Other Paroxysmal Events
1. CCEEG is recommended to identify NCS and NCSE in critically ill patients with:
a. Persistently abnormal mental status following generalized convulsive status epilepticus (GCSE) or other clinically-evident seizures
b. Acute supratentorial brain injury with altered mental status.
c. Fluctuating mental status or unexplained alteration of mental status without known acute brain injury.
d. Generalized periodic discharges (GPDs), lateralized periodic discharges (LPDs), or BIPDs (bilateral independent periodic discharges) on routine or emergent EEG. e. Requirement for pharmacological paralysis (e.g. therapeutic hypothermia protocols, extracorporeal membrane oxygenation (ECMO)) and risk for seizures.
e. Requirement for pharmacological paralysis (e.g. therapeutic hypothermia protocols, extracorporeal membrane oxygenation (ECMO)) and risk for seizures.
f. Clinical paroxysmal events suspected to be seizures, to determine if they are ictal or non-ictal.
B. Assessment of Efficacy of Therapy for Seizures and Status Epilepticus
C. Identification of Cerebral Ischemia
1. CCEEG is suggested as an adjunct method to identify ischemia in patients at high risk for ischemia.
2. Evidence. During ischemia, EEG shows a progressive sequence of changes involving loss of fast activity followed by increasing slow activity (Jordan 2004). CCEEG, and particularly quantitative EEG trends, can be used to identify changes in cortical perfusion before irreversible infarct occurs (Vespa, Nuwer et al. 1997, Claassen, Hirsch et al. 2004).
3. Assessment of clinical behavior. Concurrent video recording is recommended as a supplement to the clinical exam. Review of video can help to identify artifacts as well as changes in EEG and QEEG related to state changes.
4. Timing and duration. CCEEG should be recorded during the period of time when the patient is at highest risk for ischemia.
5. Frequency of review and interpretation. When CCEEG is performed for ischemia identification, review by CCEEG personnel should be frequent enough to allow therapeutic intervention to prevent or reverse ischemic insults if CCEEG
identifies changes potentially related to ischemia. The optimal frequency of review has not been determined and may vary for different indications.
6. Because it is difficult to identify changes from ischemia on raw EEG over prolonged time periods, CCEEG for ischemia should include quantitative EEG analysis, such as graphical displays of power ratios over time.
D. Monitoring of Sedation and High-Dose Suppressive Therapy
E. Assessment of Severity of Encephalopathy and Prognostication
CCEEG is an emerging technique to identify secondary brain injuries such as seizures and ischemia in critically ill patients. There is increasing evidence that these secondary injuries
can worsen neurologic outcome, although no prospective studies have yet demonstrated that treatment of EEG-identified changes improves neurologic outcome. The most common indication for CCEEG is for identification of NCS and NCSE, with ischemia identification and prognostication as less common uses.
(2) Consensus statement on continuous EEG in critically ill adults and children, part I: indications [PubMed Abstract] [Full Text HTML] [Full Text PDF]. J Clin Neurophysiol. 2015 Apr;32(2):87-95. doi: 10.1097/WNP.0000000000000166.
(3) Consensus statement on continuous EEG in critically ill adults and children, part II: personnel, technical specifications, and clinical practice [PubMed Abstract] [Full Text HTML] [Full Text PDF]. J Clin Neurophysiol. 2015 Apr;32(2):96-108. doi: 10.1097/WNP.0000000000000165.