Brief Communication Should we standardize the EEG classification of mild, moderate, and severe cerebral dysfunction? Saman Zafar ⁎ ,1 , Joseph Doria, Steven Karceski Department of Neurophysiology, New York Presbyterian Hospital, Weill Cornell Medical Center, 525 E 68 St, New York, NY 10065, United States of America 1. Discussion 1.1. Should we standardize the EEG classification of mild, moderate, and se- vere cerebral dysfunction? For those reporting continuous electroencephalograms (EEGs) on a regular basis, seizures are no longer the main finding. Most inpatient EEGs report cerebral dysfunction, and the various forms and morphol- ogies of this all-encompassing term are described without much stan- dardization across centers. As the use of continuous EEG monitoring for unexplained confusion (‘altered mental status’) grows, more sub- clinical seizures are being diagnosed. Additionally, there has been a rise in reports of ‘cerebral dysfunction’, which has led to several new questions: 1. When the EEG is ‘diffusely slow’, indicating the presence of ‘cerebral dysfunction’, what does that mean to the clinician? There is no stan- dardized scale for quantifying cerebral dysfunction on EEG, and the terms ‘mild’, ‘moderate’, and ‘severe’ cerebral dysfunction are variably used. 2. Would standardization be helpful? 3. Are there similar other scales in medicine, and are they helpful? 4. If there was a standardization for mild, moderate, and severe cerebral dysfunction on EEG, what proof is there that it correlates, in some way, to the degree of encephalopathy that the patient manifests on clinical examination? 5. Have there been attempts to address this problem in the past, and what have we learned from past efforts? 6. Can we propose a simple EEG scale for cerebral dysfunction in this ar- ticle, and generate discussion on this important topic? We will attempt to answer these questions below: 1. When the EEG is ‘diffusely slow’, what does that mean to the clini- cian? There is no standardized scale for quantifying cerebral dysfunc- tion on EEG, and the terms ‘mild’, ‘moderate’, and ‘severe’ cerebral dysfunction are variably used. “Diffuse slowing” on the EEG can mean slowing of the posterior dominant rhythm (PDR) (b 8.5 Hz) at one end of the spectrum, to a non- reactive delta coma on the other hand. For a neurologist or epileptologist, it may be intuitive to read through the details of an EEG report and make an opinion, but for non-neurologists, there is no dis- criminatory value of this impression. This deficiency in EEG reporting is becoming more apparent as the use of continuous EEG for unex- plained encephalopathy increases. 2. Would standardization be helpful? In a recent survey by the American Clinical Neurophysiology Society (ACNS) in 2017 [1], 110 responses were obtained from Critical Care EEG Monitoring Research Consortium (CCERMC) participants, and 83% agreed that a standardized approach to grading EEG level of brain dys- function is needed. This survey concluded that broadening the current ACNS EEG terminology in future revisions to include an encephalopathy grading scale may be useful. 3. Are there similar other scales in medicine, and are they helpful? Ordinal or quantitative scales using terms such as “mild, moderate and severe” have been used in neurology for various disorders. For example, the widely used classification for traumatic brain injury (TBI) [2], based on GCS, posttraumatic amnesia, and neuroimaging, has been adopted by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) and is easy to use. However, because of concerns about the lack of correlation to prognosis or patho- physiology, several other classifications have been proposed [3]. These may be more accurate but have not become as universal. This may set a useful precedent as we embark on trying to classify EEG background cerebral dysfunction: a simple classification may not be the best classi- fication but has a better chance of being applied universally and becom- ing common language among clinicians. Another example is the classification of hepatic encephalopathy based on the West Haven Criteria [4]. This is a simple clinical tool to clas- sify hepatic encephalopathy on a scale of 1–4, based on clinical findings such as trivial lack of awareness at the mild end of the scale to coma at the extreme end. The West Haven scale has been criticized for being overly simplistic and insufficient in capturing the full picture of the de- gree of hepatic dysfunction [5]. Once again, like the TBI classification is- sues, there have been proposals to make the classification more Epilepsy & Behavior 112 (2020) 107332 ⁎ Corresponding author. E-mail addresses: ZafarSam@einstein.edu, saz9026@nyp.org (S. Zafar), jod9184@med.cornell.edu (J. Doria), stk9005@med.cornell.edu (S. Karceski). 1 Presently Neurohospitalist — since July 1, 2020. Einstein Medical Center Philadelphia, 5501 Old York Road, Philadelphia 19141, United States of America. YEBEH-107332; No of Pages 4 https://doi.org/10.1016/j.yebeh.2020.107332 1525-5050/© 2020 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Epilepsy & Behavior journal homepage: www.elsevier.com/locate/yebeh