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ICU Clinical Correlates: EEG Patterns in the Critically Ill Suzette LaRoche, MD Assistant Professor of Neurology Emory University  Outline Background- ICU EEG Monitoring EEG Patterns in the ICU – Seizures – Periodic Patterns – Background patterns...

ICU Clinical Correlates: EEG Patterns in the Critically Ill Suzette LaRoche, MD Assistant Professor of Neurology Emory University  Outline Background- ICU EEG Monitoring EEG Patterns in the ICU – Seizures – Periodic Patterns – Background patterns – Artifacts Mystery Cases Why Continuous EEG?  Why Continuous EEG in the NICU? Detect subclinical seizures Characterize spells or movements Monitor burst-suppression/ Assess sedation level Prognostic information Detect focal or diffuse ischemia  After GCSE 48% DeLorenzo,N=164 AMS 37% Privitera, N=198 Detecting NCS by cEEG Lobar ICH 36% Vespa, N=63 TBI 22% Vespa, N=94 SAH 18% Claassen,N=108 Jordan 34% N=124 27% Pandian N=105 Claassen 19% N=570 Emory 2008 13% N=421 50 45 40 35 30 25 20 15 10 5 0 Percent  Mortality of NCS/NCSE Independent of Etiology Electrographic szs after GCSE – DeLorenzo ‘98 No Szs 13% NCS 32% NCSE 51% – Jaitly ’97 Slowing Ictal d/c 25% 41% Time to diagnosis -Young ‘96 24 hrs 36% Duration – Young ‘96 75% 20 hrs 10% 85%  Prognosis-AAN Practice Parameter Review predictors of outcome in comatose survivors of cardiac arrest 1966-2006 Level A: absent pupil response, corneals, motor response at 3 days Level B: bilaterally absent cortical responses on SSEPs at 3 days or myoclonic status epilepticus Level C: EEG suppression, burst-suppression or GPEDs Wijdicks et al. Neurology 67:203-210, 2006.  cEEG Findings Predictive of Outcome in SAH 116 patients underwent cEEG and assessed with modified Rankin Scale at 3 months Overall poor outcome in 69% Independent predictors of poor outcome: – Any periodic discharges (PEDs)- 90% vs. 63%, OR 9.0 – Absence of sleep architecture- 80% vs. 47%, OR 4.3 – Absence of reactivity- 100% – GPEDs or BiPLEDs- 100% – NCSE in first 24 hrs- 100% Claassen, Neurocritical Care, 2006  cEEG Influences Medical Decision Making 73 pts. undergoing cEEG Decisive 51% Contributing 31% 82% Most common management changes: Initiate or change AED Emergent CT scan Jordan, J Clin Nphys 1993  Spectrum of Cerebral Activity Probably Not Ictal Interictal Ictal Monomorphic GPDs LPDs LPDs + FIRDA Delta Burst- Rhythmic SIRPIDs BiLPDs Suppression Triphasics Spikes Intermittent Spikes Neuronal Injury: Cause or Effect ? Frequency, Duration, Rhythmicity Clinical Correlate  Criteria for Non-Convulsive Seizure Any pattern >10 seconds and one of the following: – Repetitive spikes or sharp waves at least 3 Hz – Rhythmic discharges >1 Hz and unequivocal evolution in frequency, morphology, location – Repetitive spike or sharp waves < 3 Hz AND significant clinical improvement and appearance of normal EEG pattern after administration of rapid acting AED NOTE: Triphasic waves can be abolished by administration of benzodiazepines. This alone does not confirm the activity was ictal. Young, Neurology 1996. Hirsch J Clin Neurophys 2005 24 yo, Refractory Status Epilepticus PHT, PB, LCM, Midazolam  Treatment? BENEFITS RISKS High mortality of status AED toxicity Avoid Increase ICP Hepatotoxicity Avoid cardiac Drug Interactions complications HYPOTENSION  Spectrum of Cerebral Activity Probably Not Ictal Interictal Ictal Monomorphic GPDs LPDs LPDs + FIRDA Delta Burst- Rhythmic SIRPIDs BiLPDs Suppression Triphasics Spikes Intermittent Spikes Neuronal Injury: Cause or Effect ? Frequency, Duration, Rhythmicity Clinical Correlate  PLEDs (Periodic Lateralized Epileptiform Discharges) 50-100% association with seizures Acute infarct, infection, hematoma, tumor – +/- metabolic disturbance BiPLEDs less common – Anoxia, infection, chronic epilepsy – Worse outcome? (few studies, small numbers) Pre-ictal, Ictal or Post-ictal? – Increased perfusion per PET and SPECT – EPC with time locked focal movements has been demonstrated – Sub-categorization of PLEDs? F p1 -F7 F 7-T 3 T 3-T 5 T 5-3 1 F p2 -F8 F 8-T 4 T 4-T 6 T 6-O2 F p1 -F3 F 3-C3 C3 -P3 P 3-3 1 F p2 -F4 F 4-C4 C4 -P4 P 4-O2  GPEDs (Generalized Periodic Epileptiform Discharges) “Rare” prior to cEEG Associated with seizures, anoxia but also severe metabolic encephalopathy Nearly 100% mortality in early studies Long interval discharges (SSPE) Short interval discharges (CJD) Triphasic waves a “variant”?  Triphasic Waves High amplitude, positive discharge Each phase longer than the preceding Frontally predominant +/- A-P lag Hepatic or renal encephalopathy Anoxia Ictal? Can be suppressed with benzodiazepines but this does NOT prove pattern is a seizure Continuous EEG Monitoring Consortium Training Module  Frontally Predominant Intermittent Rhythmic Delta Activity (FIRDA) High amplitude, bisynchronous slow waves Typical frequency of 2- 2.5 Hz May be abolished by alerting or eye opening Often seen with triphasic waves Usually implies distal, subcortical or brainstem damage (projected rhythm) Typically seen in toxic-metabolic disturbances May see with large midline structural lesions or increased ICP with herniation Continuous EEG Monitoring Consortium Training Module  SIRPIDS* Stimulus induced rhythmic, periodic, or ictal discharges 33 of 150 pts. undergoing cEEG (22%) PLEDs, GPEDs, triphasics, focal or generalized ictal patterns 50% experienced clinical or subclinical seizures during hospitalization 33% in status epilepticus at some point – Associated with focal or ictal appearing discharges Reactivity? Pathophysiology? Hirsch et al, Epilepsia 2004  Periodic Patterns-Take Home The distinction between ictal, interictal and not ictal is often not clear EEG alone can fail to clearly differentiate status from encephalopathy Critical Questions: – Are these discharges causing neuronal damage or neurological consequences? – Do they have prognostic significance? – Are they treatable and if so will suppressing them improve outcome? Other Background Patterns in the ICU Sedative Effect SDH 21 yo with Subarachnoid Hemorrhage Sensitivity 10 uV/mm 21 yo Subarachnoid Hemorrhage, Craniotomy, Herniation Artifact Artifact Artifact Mystery Cases 69 yo, Triple CABG, Aortic Aneurysm Graft  12 hours later…. Increase Keppra from 1000 mg/d to 1500 mg/d “Take these electrolytes off my head” 44 yo Left Temporal Contusion 44 yo L Temporal Contusion, After Phenytoin Load Predict EEG Findings  Outline Background- ICU EEG Monitoring EEG Patterns in the ICU – Seizures – Periodic Patterns – Background patterns – Artifacts Mystery Cases