Blog Viewer

Clio Rubinos MD, MSCR, University of North Carolina, Chapel Hill, NC

Maria Jose Bruzzone MD, MSCR, University of Florida, Gainesville, FL

This article is also available in Spanish: https://currents.neurocriticalcare.org/blogs/currents-editor/2022/06/07/monitoreo-continuo-de-eeg-en-las-unidades-de-cuida 

Introduction

The use of continuous electroencephalogram (cEEG) monitoring in the intensive care unit (ICU) has increased significantly in the United States and other high-income countries (HIC) over the last few years.¹ Seizure detection, especially for nonconvulsive seizures, is the most common indication for cEEG. Indeed, seizures are a common complication in a wide variety of critically ill patients and are not exclusive to the neuro ICU. In the medical ICU, up to 22% of patients without brain injury who undergo cEEG monitoring have periodic discharges (PDs) or seizures.² In the surgical ICU, up to 16% of patients monitored with cEEG have seizures and 29% have PDs.³

Due to this high prevalence, guidelines from the American Clinical Neurophysiology Society (ACNS) recommend cEEG monitoring for at least 24 hours in patients suspected to have nonconvulsive seizures (NCSz).⁴  The recommended length of cEEG monitoring is based on literature that suggests a higher probability of seizure detection with a longer duration of monitoring.⁵ However, prolonged cEEG monitoring is expensive, labor-intensive, and not always available. In contrast with the widespread use of cEEG in the ICU in the United States, and transfer to a tertiary center with 24/7 cEEG monitoring is an option, EEG access in the rest of the world is highly variable. A recent multicenter study surveyed 61 centers from 17 countries and found that the vast majority (69%) do not have access to prolonged cEEG (i.e., monitoring for more than 12 hours). In Latin America, out of the four centers that responded, one had no access to EEG at all, one had access to only 3 hours of cEEG or less, and two had access to up to 12 hours of cEEG, but with monitoring limited to daytime hours.⁶ While this is a small sample of Latin American centers, it represents the reality for most low- and middle-income countries (LMIC). 

Barriers to cEEG Monitoring

Some barriers to cEEG monitoring in LMICs include insufficiently trained personnel, insufficient funding for expensive EEG equipment, and a lack of availability of sufficient data storage. Integrating cEEG in ICU settings demands a team of qualified EEG readers who can give prompt clinical interpretations of studies, whether reading in the hospital or via live remote capabilities. It also requires technologists who can initialize the EEG studies, provide maintenance of EEG leads as needed, and monitor live EEG recordings to determine the need for troubleshooting. These personnel are limited in many LMIC healthcare settings, creating significant challenges in providing optimal neurotelemetry in the ICU and elsewhere. Additionally, the neurological workforce is scarce and unequally distributed in LMICs, with only 0.13 and 0.03 adult neurologists per 100 000 people in LMICs and low-income countries, respectively, compared to 4.75 adult neurologists per 100 000 people in HICs.⁷ 

Optimizing the Use of cEEG Monitoring

Despite these challenges, there is still an opportunity to increase and optimize the use of cEEG monitoring in LMICs, which could aid seizure detection and early intervention. One way is to increase the skills of non-neurologist clinical and technical personnel in recognizing common EEG patterns seen in the ICU, including electrographic seizures. Creating training programs can facilitate access to educational materials, especially if they are made available on easy-to-access platforms and at little or no cost. Training programs should be complemented by establishing recurring inter-institutional meetings to discuss EEG cases or other ICU EEG related topics to consolidate acquired knowledge. Over the last three years, our team has provided a Spanish 101 online course on the reading and understanding of EEG, with a Spanish adult and pediatric critical care course that has been endorsed by the ACNS. Similarly, other colleagues have been working on providing education in epilepsy care and surgical management in Africa and Latin America, including monthly meetings to discuss challenging surgical epilepsy cases in the latter.

Resource allocation and utilization are also important factors to address, as not every critically ill patient needs prolonged cEEG monitoring. As a matter of fact, cEEG for seizure detection doesn't necessarily need to last 24-48 hours in all cases. Evidence suggests that the 72-hour seizure risk is less than 5% in patients suspected to have NCSz but who do not have any epileptiform abnormalities in the first 2 hours of EEG monitoring. As a result, prolonged cEEG monitoring for more than 2 hours may not be necessary in these patients.⁸ Additionally, among patients who experience seizures during EEG monitoring, a seizure occurs within the first 30 minutes of monitoring in as many as 58% of cases,⁸ supporting the use of routine EEGs as an essential tool for early electrographic seizure detection.

The length of cEEG can also be personalized for each patient using risk stratification tools like the 2HELP2B score. This recently developed and externally validated score uses clinical and one-hour electrographic data to assess the required length of cEEG to achieve a negligible (less than 2%) seizure risk. The 2HELP2B score can therefore be used for triage purposes to determine which patients would benefit from more prolonged cEEG monitoring.^9,10

Finally, when cEEG is unavailable, the performance of serial routine EEGs can be an alternative in patients with a high suspicion of NCSz (i.e., if their exam does not improve). In a recent study of critically ill patients with impaired consciousness but no known seizures, the use of routine EEG for the diagnosis and management of NCSz was not associated with worse outcomes compared to cEEG.¹¹ Such data should be reassuring to providers in LMICs where cEEG is undoubtedly a luxury, as though cEEG is seen as an essential tool for monitoring patients at risk for seizures in HICs, performing serial routine EEGs can be a viable alternative. 

Future Directions

Different regions and countries have diverse challenges and needs related to access to technology, infrastructure, and staff. While limited access to technology is an issue without an easy solution, a starting point must include the mapping of neurological resources in LMICs. This information could pave the way for solutions that enhance local resources and provide optimal cEEG monitoring care. More work is needed to support the growth and access to cEEG use in LMICs. It is important to create alliances and collaborations with local authorities as well as trainees and physicians across multiple disciplines to optimize its use. Additionally, societies and institutions should partner with community members and local governments to develop relevant infrastructure, while considering data and perspectives from LMICs as part of more inclusive management guidelines. 

References

1. Hill, C. E. et al. Continuous EEG is associated with favorable hospitalization outcomes for critically ill patients. Neurology 92, E9–E18 (2019).
2. Carrera, E. et al. Continuous Electroencephalographic Monitoring in Critically Ill Patients With Central Nervous System Infections. Arch. Neurol. 65, 1612–8 (2008).
3. Kurtz, P. et al. Continuous electroencephalography in a surgical intensive care unit. Intensive Care Med. 40, 228–234 (2014).
4. Herman, S., Abed, N. & Bleck, T. Consensus sttement on Continuous EEG in Critically Ill adults and children, Part II: Personnel, technical Specification and clinical practice. 22, 134–139 (2015).
5. Claassen, J. et al. Detection of electrographic seizures with continuous EEG monitoring in critically ill patients. Neurology 62, 1743–1748 (2004).
6. MacDarby, L., Healy, M. & McHugh, J. C. EEG Availability in the Intensive Care Setting: A Multicentre Study. Neurocrit. Care 34, 287–290 (2021).
7. ATLAS Country Resources for Neurological Disorders. Available at: https://www.who.int/publications/i/item/atlas-country-resources-for-neurological-disorders.
8. Westover, B. Shafi, M. Bianchi M, et al. The probablity of seizures during EEG monitoring in critically ill adults. Clin Neurophysiol. 126(3):463 - 471 (2015) 9.        Struck, A. F. et al. Time-dependent risk of seizures in critically ill patients on continuous electroencephalogram. Ann. Neurol. (2017). doi:10.1002/ana.24985
9. Struck, A. F. et al. Assessment of the Validity of the 2HELPS2B Score for Inpatient Seizure Risk Prediction. JAMA Neurol. 77, 500–507 (2020).
10. Rossetti, A. O. et al. Continuous vs Routine Electroencephalogram in Critically Ill Adults with Altered Consciousness and No Recent Seizure: A Multicenter Randomized Clinical Trial. JAMA Neurol. 77, 1225–1232 (2020).