What is the recommended treatment for seizures with changing EEG (electroencephalogram) activity?

Treatment of Seizures with Changing EEG Activity

For seizures refractory to benzodiazepines, administer fosphenytoin, levetiracetam, or valproate as second-line agents—all three demonstrate similar efficacy in terminating seizure activity. 1

Initial Management Approach

First-Line Treatment: Benzodiazepines

• Administer lorazepam 4 mg IV slowly at 2 mg/min as first-line therapy, which demonstrates 65% efficacy in terminating status epilepticus 2
• Lorazepam provides longer duration of action compared to other benzodiazepines and is significantly superior to phenytoin for overt status epilepticus 3
• Ensure airway patency, establish IV access immediately, and monitor vital signs continuously while initiating treatment 2

Second-Line Treatment for Benzodiazepine-Refractory Seizures

When seizures persist despite optimal benzodiazepine dosing, emergency physicians should treat with one of three equally effective second-line agents: 1

Valproate Dosing

• Administer 30 mg/kg IV at 6 mg/kg/hour infusion rate 1, 2
• Achieves 88% seizure control within 20 minutes and demonstrates 79% efficacy versus 25% with phenytoin 2
• In the ESETT trial, valproate achieved cessation of status epilepticus and improvement in consciousness at 60 minutes in 46% of patients 1

Levetiracetam Dosing

• Administer 30 mg/kg IV (up to 4500 mg maximum) at 5 mg/kg/min 1, 2
• Demonstrates 73% response rate in refractory status epilepticus with equivalent efficacy to valproate (47% cessation at 60 minutes) 1, 2
• Loading doses ≤20 mg/kg show 92.9% seizure termination at 60 minutes, while doses ≥40 mg/kg show 84.7% termination but higher intubation rates (45.8% vs 26.8%) 4
• Optimal dosing appears to be 20-30 mg/kg to balance efficacy with safety 4

Fosphenytoin Dosing

• In the ESETT trial, fosphenytoin achieved 45% cessation of status epilepticus at 60 minutes 1
• Associated with 3.2% rate of life-threatening hypotension compared to 0.7% with levetiracetam 1

EEG Monitoring Requirements

When to Obtain EEG

• Emergent EEG should be obtained in patients with altered consciousness after motor seizures, suspected nonconvulsive status epilepticus, or patients who do not return to functional baseline within 60 minutes after seizure medication 3
• Consider continuous EEG monitoring for patients with diagnosed status epilepticus to monitor treatment effects 1
• EEG is the definitive test for detecting ongoing electrical seizure activity, particularly when clinical manifestations are subtle or absent 3

Interpreting EEG Changes

• Electrographic seizures require treatment with antiseizure medications even without clinical manifestations 1, 3
• Rhythmic and periodic EEG patterns that do not meet criteria for electrographic seizures are of unclear significance—post hoc analysis of the TELSTAR trial suggested possible benefit in treating electrographic seizures but not periodic discharges 1
• Propofol and conventional antiseizure medications (valproate and levetiracetam) can suppress epileptiform activity on EEG 1, 3

Critical Pitfalls to Avoid

Do Not Assume Generalized Slowing Equals Seizure Activity

• Generalized slowing on EEG typically represents diffuse cortical dysfunction from non-epileptic causes such as metabolic encephalopathies (hepatic encephalopathy, renal dysfunction, hyponatremia, hypoxia) 5
• Inappropriate antiepileptic drug escalation for generalized slowing may worsen the underlying condition 5
• Correct metabolic abnormalities immediately rather than escalating antiseizure medications 5

Avoid Prophylactic Anticonvulsants

• Do not use prophylactic anticonvulsants after single self-limited seizures 2
• Prophylactic anticonvulsants in stroke patients show no benefit and possible harm to neural recovery 1, 2
• Meta-analyses of levetiracetam prophylaxis in traumatic brain injury, subarachnoid hemorrhage, and intracerebral hemorrhage did not demonstrate significant reductions in seizure incidence 6

Safety Considerations

• Life-threatening hypotension occurs in 0.7% with levetiracetam, 3.2% with fosphenytoin, and 1.6% with valproate 1
• Endotracheal intubation rates are 20% with levetiracetam, 26.4% with fosphenytoin, and 16.8% with valproate 1
• Levetiracetam doses >40 mg/kg are associated with significantly higher intubation rates without improved efficacy 4

Treatment of Specific EEG Patterns

For Electrographic Status Epilepticus

• Treat with sodium valproate, levetiracetam, phenytoin, benzodiazepines, propofol, or barbiturates 1
• Whether systematic detection and treatment of electrographic epileptic activity without clinical manifestations improves patient outcome remains unknown 1

For Post-Anoxic Myoclonus

• Phenytoin is often ineffective for myoclonus 1
• Propofol is effective to suppress post-anoxic myoclonus 1
• Clonazepam, sodium valproate, and levetiracetam are antimyoclonic drugs that may be effective 1
• Myoclonus in combination with epileptiform discharges may be manifestations of Lance-Adams syndrome, which is compatible with good outcome—overly aggressive treatment may not be warranted 1