ACNS Critical Care EEG Terminology: Electrographic and Electroclinical seizures, BIRDs and the Ictal-Interictal Continuum - Yale University New ...
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ACNS Critical Care EEG
Terminology: Electrographic and
Electroclinical seizures, BIRDs
and the Ictal-Interictal Continuum
Lawrence J. Hirsch, MD, FACNS
Yale University
New Haven, Connecticut, USA
2021
Disclosures, relevant
⚫I bill for continuous EEG monitoring (about 25%
of my clinical billing)
⚫ I co-authored the Atlas of EEG in Critical Care
(Hirsch and Brenner)
⚫ I borrowed some slides from the Critical Care
EEG Monitoring Research Consortium, guideline
co-authors, and Yale colleagues
⚫ Suzette Laroche, Nicholas Abend, Tammy Tsuchida, Sue Herman, Nicolas Gaspard, Brandon
Westover, Suzette Laroche, Andres Rodriguez, Nicolas Gaspard, Emily Gilmore, Gamal Osman,
Jiyeoun Yoo, Carolina Maciel, Nishi Rampal, Michael Fong, Markus Leitinger
Disclosures, unrelated ⚫ Consultant ⚫ Accure; Aquestive; Ceribell; Eisai; Medtronic; Neuropace; UCB ⚫ Honoraria for speaking ⚫ Neuropace; Natus ⚫ Royalties ⚫ Wolters Kluwer (UpToDate); Wiley
American Clinical
Neurophysiology Society’s
Standardized Critical Care
EEG Terminology
J Clin Nphys, 2013
Some slides from the official
CCEMRC Training Module (www.acns.org)
Lawrence Hirsch, Nicolas Gaspard, Brandon Westover,
Suzette Laroche
4
2021 Terminology has arrived! J Clin Nphysiol Jan 2021 Thanks to all co-authors. Special thanks to Michael Fong and Markus Leitinger for helping with the publication, diagrams, figures, EEG samples and slides
Modifiers: Evolution
At least 2 unequivocal, sequential changes in
frequency, morphology or location defined as
follows:
⚫ Frequency: ≥2 consecutive increases or decreases
of ≥0.5/s, (e.g. 2 → 2.5 to 3/s, or 3 → 2 to 1.5/s)
⚫ Morphology: ≥2 consecutive changes to a novel
morphology;
⚫ Location : sequentially spreading into/out of ≥2
different standard 10-20 electrode locations.
⚫ NOTE:
⚫ if evolving and >10s: it’s a seizure.
⚫ If evolving, 0.5-10s and reaches >4 hz, it’s a BIRD
(definite due to evolution)
⚫ If evolving, 4 Hz, just use the modifier
“evolving”
Evolution of frequency At least 2 unequivocal, sequential changes in frequency: at least 2 consecutive changes in the same direction by at least 0.5 Hz. To qualify as present, a single frequency must persist for at least 3 cycles. The criteria for evolution must be reached without the evolving feature (frequency) remaining unchanged for 5 or more continuous minutes.
Evolution of morphology
At least 2 consecutive changes to a novel morphology. Each different
morphology or each morphology plus its transitional forms must last at
least 3 cycles.
9
Evolution
of
location
Sequentially spreading into
or sequentially out of at least
two different standard 10–20
electrode locations. To
qualify as present, a single
location must persist for at
least 3 cycles.
10Modifiers, cont’d: Fluctuating At least 3 changes,
Fluctuation in frequency >3 changes, not more than one minute apart, in frequency (by at least 0.5 Hz), but not qualifying as evolving. This includes patterns fluctuating from 1 to 1.5 to 1 to 1.5 Hz. To qualify as present, a single frequency must persist at least 3 cycles (e.g. 1 Hz for 3 seconds, or 3 Hz for 1 seconds).
Unified EEG criteria for nonconvulsive status epilepticus
“The Salzburg Criteria”
Sándor Beniczky1,2,*, Lawrence J. Hirsch3, Peter W. Kaplan4, Ronit Ressler5, Gerhard Bauer6, Harald
Aurlien7,8, Jan C. Brøgger7,8, Eugen Trinka9; Epilepsia SEP 2013
• EDs > 2.5 Hz, or
• EDs ≤ 2.5 Hz or rhythmic delta/theta activity (>0.5 Hz) AND one of the
following:
• EEG and clinical improvement after IV AED , or
• Subtle clinical ictal phenomena during the EEG
patterns mentioned above, or
• Typical spatiotemporal evolution**
**Incrementing onset (increase in voltage and change in frequency), or evolution in pattern
(change in frequency >1 Hz or change in location), or decrementing termination (voltage or
frequency).
• If EEG improvement occurs without clinical improvement, or if fluctuation without
definite evolution, this should be considered possible NCSE.Leitinger M et al, Lancet Neurol 2016. Conclusion: “The Salzburg criteria for diagnosis of NCSE have high diagnostic accuracy and excellent inter-rater agreement, making them suitable for implementation in clinical practice.”
Electrographic Seizure (Esz) and
Electrographic Status (ESE)
(largely based on the Salzburg criteria [Beniczky S et al, Epilepsia 2013;
Leitinger M et al, Lancet Neurol 2016])
⚫ Epileptiform discharges averaging >2.5
Hz for >10 seconds (>25 discharges in
10 seconds), OR
⚫ Any pattern with definite evolution and
lasting >10 seconds
⚫ Electrographic status epilepticus (ESE) is defined as
electrographic seizure for >10 continuous minutes or
for a total duration of >20% of any 60-minute period
15
of recordingElectrographic seizure (ESz):
Epileptiform discharges >2.5 Hz for ≥10 s (>25 ED in 10s)
Example: 26 EDs per 10 s
tim
e
1s 2s 3s 4s 5s 6s 7s 8s 9s 10
s
10 s
OR
Any pattern with definite evolution lasting ≥10 sElectrographic seizure
73, astrocytoma resection, csf leak, meningitis, rare clinical seizures.
EEG 1 of 273, astrocytoma resection, csf leak, meningitis, rare clinical seizures.
EEG 2 of 2Electroclinical seizure (ECSz)
⚫ Any EEG pattern with either:
⚫ A definite clinical correlate (even if subtle) time-locked to the
pattern (of any duration), OR
⚫ EEG and clinical improvement with a parenteral (typically IV)
anti-seizure medication.
⚫ NOTE: the EEG pattern does NOT have to qualify as an
electrographic seizure
⚫ Electroclinical status epilepticus (ECSE): Electroclinical
seizure for >10 continuous minutes or for a total duration
of > 20% of any 60-minute period of recording.
⚫ NOTE: only need 5 mins if bilateral tonic-clonic
20Seizure burden is independently associated with short-
term outcome in critically ill children
Payne ET, … Hahn C. Brain 2014
• N=259 PICU patients undergoing CEEG
• Outcome: neurological decline (on Peds Cerebral
performance Category score, PCPC)
• Seizures in 36%
• Neurological decline in 67%
• If maximum hourly seizure burden was >20% (12 min),
marked rise of chance and severity of neurological decline
(but not mortality)Seizure burden is independently associated with short-term
outcome in critically ill children
Payne ET, … Hahn C. Brain 2014
22Resolution of NCSE over 11 Hours: The Ictal-Interictal Continuum
The Ictal-Interictal Continuum (IIC)
⚫ Synonymous with “possible electrographic seizure” or “possible
electrographic SE”. A pattern on the IIC is a pattern that does not qualify as
definite seizure activity, but there is a reasonable chance that it may be
contributing to impaired alertness, causing other clinical symptoms, and/or
contributing to neuronal injury. Thus, it is potentially ictal in at least some
sense, and often warrants a diagnostic treatment trial, typically with an IV
anti-seizure medication.
⚫ Any PD or SW pattern that averages >1.0 and 10 and < 25 discharges in 10 s); or
⚫ Any PD or SW pattern that averages >0.5 and 1 Hz for at least 10 s with a plus
modifier or fluctuation. This includes any LRDA, BIRDA, UIRDA,
and MfRDA, but not GRDA.
AND
⚫ Does not qualify as definite seizure activity.
24IIC: LPD+R, 1.5-2 Hz
IIC: GPD+R, 1.5-2Hz
IIC: LPD+R, 1.5 Hz
IIC: GPDs, 1.5-2 Hz (17 discharges in 10 secs)
IIC: LRDA+FS, 2 Hz
Struck A et al, Ncrit Care 2016 (MGH)
61% of 18 patients on the IIC showed
hypermetabolism on PETPossible electroclinical SE
⚫ An RPP that qualifies for the IIC that is
present for ≥10 continuous min or for a
>20% of any 60-min period, which shows
EEG improvement with a parenteral anti-
seizure medication BUT without clinical
improvement.
⚫ Largely in line with “possible NCSE” as
defined by the Salzburg criteria.
⚫ NOTE: Possible ECSE cannot include
patterns that already qualify as ESz/ESE. 31What finding on EEG should be treated?
Personal opinion
⚫ Short, oversimplified answer
⚫ Definite seizures
⚫ though often ok to tolerate a low burden of seizures, esp if
brief, refractory to multiple AEDs, and not increasing in
prevalence.
⚫ Any PDs 2 Hz or faster (see Witsch J et al, JAMA Neurol 2017)
⚫ And do a diagnostic trial for most patients with patterns
on the ictal-interictal continuum
⚫ For tough cases, include: MRI (esp DWI; maybe
perfusion), ictal SPECT, microdialysis, tissue oxygen,
serial NSE, PET
32B(I)RDs Yoo J et al, JAMA Neurol 2014
BIRDs: Brief Potentially Ictal Rhythmic
Discharges
Yoo J et al, JAMA Neurol 2014
⚫ Original def’n: 4 Hz, with
or without evolution
⚫ Usuallytheta (70%), sharply contoured, and most commonly 1-
3 seconds in duration
⚫ N=20 patients (2% of all ICU-EEG patients)
⚫ All had cerebral injury
⚫ Associated with electrographic seizures
⚫ 15/20 (75%) vs 10/40 (25%) of matched controls (pBIRDs in noncritically ill adults
Yoo JY et al, J Clin Nphys 2017
⚫ 15 patients w/ BIRDs (1.2% of EMU or ambulatory cases)
matched by age and etiology to control group in 1:2 ratio
⚫ Mostly 0.5-4 sec runs of sharply contoured alpha
⚫ All patients had epilepsy
⚫ Those w/ BIRDs were more likely to be refractory (67%
vs 17%, pBRIEF POTENTIALLY ICTAL
RHYTHMIC DISCHARGES (BIRDs)
⚫ Largely based on Yoo JY et al, JCN 2017
⚫ Focal or generalized rhythmic activity >4 Hz (at least 6
waves at a regular rate) lasting >0.5 toBRIEF POTENTIALLY ICTAL RHYTHMIC
DISCHARGES (BIRDs) , cont’d
⚫ NOTE: Paroxysmal fast activity lasting ≥0.5 toBIRDs
Three Little BIRDs
Non-evolving
Courtesy of Dr. Jiyeoun (Jenna) YooDefinite, Evolving BIRDs Courtesy of Dr. Jiyeoun (Jenna) Yoo
Definite, Evolving BIRD Courtesy of Dr. Jiyeoun (Jenna) Yoo
Definite, Non-evolving BIRDs Courtesy of Dr. Jiyeoun (Jenna) Yoo
BIRDs??: 80 yo woman, left temp stroke, clinical seizure, then not fully awake after
Seizure in same patient (onset similar to BIRD)
BIRDs and PFA: does frequency matter?
Yoo JY et al, in press, Epilepsia
⚫ 94 patients w/ BIRDs/PFA on long term EEGs (>12h)
⚫ 36 critically ill
⚫ BIRDs were slower (theta rather than alpha) when there
was no PDR or with continuous focal slowing in the same
region
⚫ Seizures in 62/94 (66%)
⚫ 32/36 (89%) in critically ill patients
⚫ 30/58 (52%) in non-critically ill people w/ epilepsy
⚫ Seizure onset zone always matched the loc’n of BIRDs
⚫ Rate of szs was the same regardless of freq of the BIRDs
⚫ All patients w/ evolving BIRDs had seizures vs 50% of
non-evolving BIRDsSporadic
epilept disch’s seizure
BIRDBIRDs, continued: Social distancing: 6 inch rule
The Ictal-Interictal Continuum
INTERICTAL POTENTIALLY ICTAL ICTAL
Any PD, SW or RDA
(except GRDA)
< 0.5 Hz 1 Hz 2.5 Hz 3.0+ Hz
No “Plus” “Plus” (+F, R, S)
GRDA Static Fluctuating Evolving
Sporadic
epilepti-
form dis-
charges Stimulus-induced GCSE
NCSE
Triphasic morphology NCSz
BIRDs
Haider, Laroche and Hirsch, 2018THANK YOU!! The Yale Comprehensive Epilepsy Center
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