What is the treatment for myoclonic status epilepticus with cardiac arrest?

Treatment of Myoclonic Status Epilepticus Following Cardiac Arrest

Treatment of myoclonic status epilepticus following cardiac arrest should include levetiracetam or valproate as first-line antiepileptic drugs, with continuous EEG monitoring to guide therapy, while avoiding aggressive treatment in cases where myoclonus may represent Lance-Adams syndrome compatible with good outcomes. 1

Initial Assessment and Differentiation

• Determine the type of myoclonus present:

  • Cortical myoclonus (with EEG correlate) - more likely to benefit from antiseizure medications
  • Subcortical myoclonus (without EEG correlate) - may not require aggressive treatment if not interfering with mechanical ventilation 1
  • Lance-Adams syndrome (myoclonus with continuous cortical background activity) - compatible with good outcomes, avoid overly aggressive treatment 1

• Obtain EEG to:

  • Distinguish between different types of myoclonus
  • Detect nonconvulsive seizures and status epilepticus
  • Guide treatment decisions 1

First-Line Treatment

• Antiepileptic medications:

  • Levetiracetam: 20-30 mg/kg IV loading dose, followed by maintenance therapy 1, 2
  • Valproate: 20-40 mg/kg IV loading dose, followed by maintenance therapy 1
  • These are preferred over fosphenytoin due to fewer adverse effects (particularly hypotension) 1, 3

• Benzodiazepines:

  • Lorazepam: 2-8 mg IV 4
  • Diazepam: 5-20 mg IV 4
  • Clonazepam: Particularly useful for myoclonus 1, 5

Second-Line Treatment (for Refractory Cases)

For cases not responding to first-line therapy:

• Sedative agents:

  • Propofol: 50-150 mg IV bolus followed by infusion at 100-500 mg/hour (particularly effective for post-anoxic myoclonus) 1, 4
  • Midazolam: 8-20 mg IV bolus followed by infusion at 4-30 mg/hour 4

• Other options:

  • Phenobarbital: 100-1000 mg IV 4
  • Consider combination therapy when single agents fail 1

Continuous Monitoring and Supportive Care

• Implement continuous EEG monitoring to:

  • Detect nonconvulsive seizures
  • Monitor treatment efficacy
  • Guide titration of medications 1

• Maintain targeted temperature management (TTM):

  • Select and maintain constant target temperature between 32°C and 36°C 1
  • Duration should be at least 24 hours 1
  • Prevent and treat fever after completion of TTM 1

Important Considerations and Pitfalls

• Avoid overly aggressive treatment in cases where myoclonus may represent Lance-Adams syndrome, which is compatible with good outcomes 1

• Be aware of special populations where good outcomes may occur despite myoclonic status:

  • Young patients
  • Primary respiratory causes of arrest
  • Presence of illicit substances 6

• Recognize potential adverse effects of treatment:

  • Sedation and high-dose antiepileptic drugs may cause delayed awakening
  • Prolonged mechanical ventilation
  • Increased critical care days 1
  • Treatment may confound neurological examination and lead to overly pessimistic prognostication 1

• Do not use routine seizure prophylaxis in post-cardiac arrest patients due to risk of adverse effects and poor response 1

• Treat severe hyperthermia aggressively as it can trigger MSE through cortical injury 2

The evidence for treating myoclonic status epilepticus after cardiac arrest is limited, with no high-certainty evidence showing positive effects of antiepileptic drugs on outcomes. However, treatment is recommended based on the potential harm of untreated seizure activity to the brain 1. The TELSTAR trial investigating systematic antiepileptic therapy versus standard treatment of clinical seizures may provide more definitive guidance in the future 1.