What is the immediate management for a patient with slowing on electroencephalogram (EEG) and impaired mental status, not following commands, after cardiac arrest?

Management of EEG Slowing After Cardiac Arrest in a Patient Not Following Commands

For a patient with EEG slowing and impaired mental status after cardiac arrest who is not following commands, immediate EEG monitoring and treatment of seizure activity is strongly recommended.

Initial Assessment and Monitoring

• Promptly perform and interpret electroencephalography (EEG) for accurate diagnosis of seizures in post-cardiac arrest patients who are not following commands (Class 1, Level of Evidence C-LD) 1
• Continuous or repeated EEG monitoring is reasonable for these patients to detect seizures and monitor brain function (Class 2a, Level of Evidence C-LD) 1
• EEG monitoring should begin as soon as possible after return of spontaneous circulation (ROSC), ideally within the first few hours 2
• EEG allows assessment of early changes in background patterns, development of seizures, and epileptiform activity despite sedation or targeted temperature management 3

Treatment Approach

For Definitive Seizures:

• Treatment of clinically apparent seizures is recommended in adult cardiac arrest survivors (Class 1, Level of Evidence C-LD) 1
• Treatment of nonconvulsive seizures (diagnosed by EEG only) is reasonable (Class 2a, Level of Evidence B-R) 1
• For electrographic seizures (epileptiform discharges averaging >2.5 Hz for ≥10 seconds or any pattern with definite evolution lasting ≥10 seconds), initiate antiseizure medication therapy 1

For Patterns on Ictal-Interictal Continuum:

• A therapeutic trial of a nonsedating antiseizure medication may be reasonable (Class 2b, Level of Evidence C-EO) 1
• This includes periodic discharges or spike/sharp-wave patterns averaging >1.0 Hz and ≤2.5 Hz, or patterns averaging ≥0.5 Hz and ≤1.0 Hz with plus modifiers or fluctuation 1

Medication Selection:

• The same antiseizure medications used for treatment of seizures from other etiologies may be considered (Class 2b, Level of Evidence C-LD) 1
• Avoid excessive sedation that could interfere with neurological assessment 1

Important Considerations

• Do not use prophylactic antiseizure medications in adult survivors of cardiac arrest (Class 3: No Benefit, Level of Evidence B-R) 1
• Distinguish between different types of myoclonus, as some forms may not warrant aggressive treatment with antiseizure medications if not interfering with mechanical ventilation 1
• Be aware that seizures occur in 10-35% of patients with cardiac arrest who do not follow commands after ROSC 1
• Postanoxic hyperexcitability can manifest as a wide range of electroclinical findings, from overt convulsions to subtle EEG patterns 1

Prognostic Implications

• Continuous EEG background activity is associated with better chances of recovery (87-90% recovery of consciousness) 4
• Patients with continuous cortical background activity and those who develop epileptiform abnormalities >24 hours after ROSC are more likely to recover 1
• Intractable and persistent status epilepticus (more than 72 hours) in the absence of EEG reactivity to external stimuli may indicate poor outcome (Class IIb, LOE B-NR) 1
• Avoid early prognostication based solely on EEG findings; the earliest time to prognosticate poor neurologic outcome is 72 hours after cardiac arrest in patients not treated with targeted temperature management 1

Pitfalls to Avoid

• Do not rely solely on clinical examination to detect seizures, as sedation, analgesia, and muscle paralysis can mask clinical signs of epileptic activity 5
• Do not assume all EEG slowing indicates seizure activity; differentiate between post-anoxic encephalopathy patterns and true seizure activity 6
• Do not use the presence of myoclonus alone to predict poor neurologic outcomes due to high false-positive rates (FPR 5-11%) 1
• Avoid delaying EEG monitoring, as early detection and treatment of seizures may improve outcomes 3