Skip to main content Accessibility help
×
Hostname: page-component-54dcc4c588-sq2k7 Total loading time: 0 Render date: 2025-09-28T13:34:20.330Z Has data issue: false hasContentIssue false

Chapter 12 - Repetitive Abnormalities

from Part II - Interpretation

Published online by Cambridge University Press:  aN Invalid Date NaN

Neville M. Jadeja
Neville M. Jadeja
Affiliation:
UMass Chan Medical School
Get access

Summary

Repetitive abnormalities are those that repeat in quick succession (rhythmic), after regular intervals (periodic), or occur as spike and wave (SW). Repetitive abnormalities may be associated with epileptic seizures but the strength of this association varies. In some cases, repetitive patterns may represent ongoing electrographic seizures (ictal patterns). According to standardized critical care EEG terminology, a repetitive pattern is described as a combination of main term 1 (location) and main term 2 (rhythmic, periodic, or spike and wave). Common rhythmic abnormalities include generalized rhythmic delta activity and lateralized rhythmic delta activity. Common periodic abnormalities include generalized periodic discharges and lateralized periodic discharges. The term SI is added to denote stimulus induced. Determining the ictal potential of a repetitive discharge is key to its appropriate management. [121 words/730 characters]

Keywords

GRDALRDALPDGPDGSWBIPD

Information

Type
Chapter
Information
How to Read an EEG , pp. 173 - 190
Publisher: Cambridge University Press
Print publication year: 2025

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Book purchase

Temporarily unavailable

References

Hirsch, LJ, Fong, MWK, Leitinger, M, et al. American Clinical Neurophysiology Society’s standardized critical care EEG terminology: 2021 version. Journal of Clinical Neurophysiology. 2021 Jan;38(1):1–29.CrossRefGoogle ScholarPubMed
Pohlmann-Eden, B, Hoch, DB, Cochius, JI, Chiappa, KH. Periodic lateralized epileptiform discharges: a critical review. Journal of Clinical Neurophysiology. 1996 Nov 1;13(6):519–30.10.1097/00004691-199611000-00007CrossRefGoogle ScholarPubMed
Chong, DJ, Hirsch, LJ. Which EEG patterns warrant treatment in the critically ill? Reviewing the evidence for treatment of periodic epileptiform discharges and related patterns. Journal of Clinical Neurophysiology. 2005 Apr 1;22(2):79–91.10.1097/01.WNP.0000158699.78529.AFCrossRefGoogle ScholarPubMed
Hirsch, LJ, Claassen, J, Mayer, SA, Emerson, RG. Stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs): a common EEG phenomenon in the critically ill. Epilepsia. 2004 Feb;45(2):109–23.10.1111/j.0013-9580.2004.38103.xCrossRefGoogle ScholarPubMed
Accolla, EA, Kaplan, PW, Maeder-Ingvar, M, Jukopila, S, Rossetti, AO. Clinical correlates of frontal intermittent rhythmic delta activity (FIRDA). Clinical Neurophysiology. 2011 Jan 1;122(1):27–31.CrossRefGoogle ScholarPubMed
Moeller, F, Pressler, RM, Cross, JH. Genetic generalized epilepsy. In Oxford textbook of clinical neurophysiology; Mills, KR Ed. (p. 301). Oxford University Press, Oxford; 2016.Google Scholar
Gaspard, N, Manganas, L, Rampal, N, Petroff, OA, Hirsch, LJ. Similarity of lateralized rhythmic delta activity to periodic lateralized epileptiform discharges in critically ill patients. JAMA Neurology. 2013 Oct 1;70(10):1288–95.Google ScholarPubMed
Di Gennaro, G, Quarato, PP, Onorati, P, et al. Localizing significance of temporal intermittent rhythmic delta activity (TIRDA) in drug-resistant focal epilepsy. Clinical Neurophysiology. 2003 Jan 1;114(1):70–8.Google ScholarPubMed
Foreman, B, Claassen, J, Khaled, KA, et al. Generalized periodic discharges in the critically ill: a case-control study of 200 patients. Neurology. 2012 Nov 6;79(19):1951–60.CrossRefGoogle ScholarPubMed
Jadeja, N, Zarnegar, R, Legatt, AD. Clinical outcomes in patients with generalized periodic discharges. Seizure. 2017 Feb 1;45:114–18.CrossRefGoogle ScholarPubMed
O’Rourke, D, Chen, PM, Gaspard, N, et al. Response rates to anticonvulsant trials in patients with triphasic-wave EEG patterns of uncertain significance. Neurocritical Care. 2016 Apr 1;24(2):233–9.10.1007/s12028-015-0151-8CrossRefGoogle ScholarPubMed
Boulanger, JM, Deacon, C, Lécuyer, D, Gosselin, S, Reiher, J. Triphasic waves versus nonconvulsive status epilepticus: EEG distinction. Canadian Journal of Neurological Sciences. 2006 Jul;33(2):175–80.CrossRefGoogle ScholarPubMed
Glauser, T, Shinnar, S, Gloss, D, et al. Evidence-based guideline: treatment of convulsive status epilepticus in children and adults: report of the Guideline Committee of the American Epilepsy Society. Epilepsy Currents. 2016 Jan;16(1):48–61.10.5698/1535-7597-16.1.48CrossRefGoogle ScholarPubMed
Punia, V, Garcia, CG,Hantus, S. Incidence of recurrent seizures following hospital discharge in patients with LPDs (PLEDs) and nonconvulsive seizures recorded on continuous EEG in the critical care setting. Epilepsy and Behavior. 2015 Aug 1;49:250–4.10.1016/j.yebeh.2015.06.026CrossRefGoogle ScholarPubMed
Ruiz, AR, Vlachy, J, Lee, JW, et al. Association of periodic and rhythmic electroencephalographic patterns with seizures in critically ill patients. JAMA Neurology. 2017 Feb 1;74(2):181–8.Google Scholar
Herman, ST, Abend, NS, Bleck, TP, et al. Consensus statement on continuous EEG in critically ill adults and children, part I: indications. Journal of Clinical Neurophysiology. 2015 Apr;32(2):87.CrossRefGoogle ScholarPubMed
Maciel, CB, Gilmore, EJ. Seizures and epileptiform patterns in SAH and their relation to outcomes. Journal of Clinical Neurophysiology. 2016 Jun 1;33(3):183–95.CrossRefGoogle ScholarPubMed
Claassen, J, Jette, N, Chum, F, et al. Electrographic seizures and periodic discharges after intracerebral hemorrhage. Neurology. 2007 Sep 25;69(13):1356–65.10.1212/01.wnl.0000281664.02615.6cCrossRefGoogle ScholarPubMed
Fitzpatrick, W, Lowry, N. PLEDs: clinical correlates. Canadian Journal of Neurological Sciences. 2007 Nov 1;34(4):443–50.10.1017/S0317167100007332CrossRefGoogle ScholarPubMed
Struck, AF, Westover, MB, Hall, LT, et al. Metabolic correlates of the ictal-interictal continuum: FDG-PET during continuous EEG. Neurocritical Care. 2016 Jun 1;24(3):324–31.10.1007/s12028-016-0245-yCrossRefGoogle ScholarPubMed
Li, HT, Wu, T, Lin, WR, et al. Clinical correlation and prognostic implication of periodic EEG patterns: a cohort study. Epilepsy Research. 2017 Mar 1;131:44–50.10.1016/j.eplepsyres.2017.02.004CrossRefGoogle ScholarPubMed

Accessibility standard: WCAG 2.2 AAA

The PDF of this book complies with version 2.2 of the Web Content Accessibility Guidelines (WCAG), offering more comprehensive accessibility measures for a broad range of users and attains the highest (AAA) level of WCAG compliance, optimising the user experience by meeting the most extensive accessibility guidelines.

Content Navigation

Table of contents navigation
Allows you to navigate directly to chapters, sections, or non‐text items through a linked table of contents, reducing the need for extensive scrolling.
Index navigation
Provides an interactive index, letting you go straight to where a term or subject appears in the text without manual searching.

Reading Order & Textual Equivalents

Single logical reading order
You will encounter all content (including footnotes, captions, etc.) in a clear, sequential flow, making it easier to follow with assistive tools like screen readers.
Short alternative textual descriptions
You get concise descriptions (for images, charts, or media clips), ensuring you do not miss crucial information when visual or audio elements are not accessible.
Full alternative textual descriptions
You get more than just short alt text: you have comprehensive text equivalents, transcripts, captions, or audio descriptions for substantial non‐text content, which is especially helpful for complex visuals or multimedia.

Visual Accessibility

Use of colour is not sole means of conveying information
You will still understand key ideas or prompts without relying solely on colour, which is especially helpful if you have colour vision deficiencies.
Use of high contrast between text and background colour
You benefit from high‐contrast text, which improves legibility if you have low vision or if you are reading in less‐than‐ideal lighting conditions.

Save book to Kindle

To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×