Electroencephalography in the ICU: Monitoring the Critically Ill Brain
Selina Husna Banu *
ICH and GOSH, University College London, UK, Presbyterian Hospital, NY, USA, Department of Clinical Neurophysiology and Sleep Clinic, Oxford University College Hospital, UK and Department of Neurology and Development, Dr. MR Khan Shishu Hospital and Institute of Child Health, Mirpur, Dhaka, Bangladesh.
*Author to whom correspondence should be addressed.
Abstract
Electroencephalography is an essential tool to assess the real-time cerebral function and identify the dysfunctions at any age and state, including newborns to critically ill patient at the pediatric and adult ICU. The rapid identification and intervention of vital organ dysfunction is the key to preventing irreversible brain damage in the ICU. Continuous EEG monitoring provides a window to brain function, allowing clinicians to start the treatment or limit the medicine dose in a critically ill, unconscious patient. The analysis of recorded data provides dynamic information about the brain function that permits early detection of changes in neurologic status, which is especially useful when the clinical examination is limited. Simplified, bedside monitoring with limited electrodes (aEEG) at the neonatal intensive care unit (NICU) may provide instant diagnostic and prognostic information about ongoing subclinical seizure, neuronal functional maturity, coma-state, presumed recovery, quality of life assessment, and predict neurodevelopmental outcome. In case of critically ill patients at the ICU, identification of ongoing electrographic seizures, non-convulsive status epilepticus (NCSE), periodic epileptogenic discharges (PED), and irreversible cerebral dysfunction, i.e., isoelectric tracing, would help the care providers in appropriate decision-making regarding the management. Non-convulsive seizures (NCSz) are more common than previously recognised and are associated with worse outcomes if not treated in time. The prevalence of NCSz identified was 8% in 236 patients in a coma state of all age groups (1 month - 87 years), 39% among 117 children in a coma state. Half of them were detected with one hour of cEEG, 20% needed 24 or more hours of cEEG. This indicates the importance of cEEG use at ICU. Studies revealed the first NCSz within 1 to 24 hours of EEG monitoring; a longer period of monitoring is required in comatose patients and those with PED.
In a resource-poor situation, EEG is frequently requested to confirm brain death, particularly where there is limited information on neurological examination or an inconclusive apnea test, or when the patient is in a prolonged state of coma. Presence of isoelectric tracing for at least 30 minutes in the EEG, along with other clinical evidences is helpful in such situations.
Extreme care should be taken for recording and reviewing continuous EEG (cEEG) monitoring at the ICU, where sources of electrical noise are present.
Real-time detection of ischemia at a reversible state is technologically feasible with cEEG and should be developed into a practical form for the prevention of in-hospital infarction. Continuous EEG (cEEG) is the gold-standard tool for detecting non-convulsive status epilepticus (NCSE) in ICUs, NICUs, and other critical care settings, improving neurological outcomes (ACNS). Its use is limited by the need for skilled technologists and extensive infrastructure. Portable, point-of-care, and rapid-setup EEG systems with fewer electrodes have been shown to provide high-quality bedside monitoring, increasing accessibility in resource-limited settings.
Keywords: Electroencephalographic monitoring, electrographic seizures, non-convulsive seizures, status epilepticus, traumatic brain injury, cerebral haemorrhage