What is the management approach for non-convulsive seizure (NCSE)?

Management of Non-Convulsive Status Epilepticus (NCSE)

The management of NCSE should follow a stepwise approach beginning with benzodiazepines (lorazepam 0.05 mg/kg IV) followed by levetiracetam (40 mg/kg IV), with additional agents added if seizures persist. 1, 2

Diagnosis and Initial Assessment

• NCSE can only be definitively diagnosed with EEG monitoring 2
• High-risk populations for NCSE include:
  • Elderly patients, particularly those on psychotropic medications
  • ICU patients
  • Post-convulsive seizure patients
  • Patients with unexplained altered mental status or encephalopathy 2, 3
• After control of convulsive status epilepticus, up to 48% of patients may have persistent electrographic seizures, with 14% developing NCSE 3

Treatment Algorithm for NCSE

First-Line Treatment:

• Assess circulation, airway, and breathing (CAB)
• Provide airway protection if needed
• Administer high-flow oxygen
• Check blood glucose level
• Lorazepam 0.05 mg/kg IV (maximum 1 mg)
  • May repeat every 5 minutes to a maximum of 4 doses to control electrographic seizures 1

Second-Line Treatment:

• Levetiracetam 40 mg/kg IV (maximum 2,500 mg) as bolus 1
  • Success rate of 44-73% 2
  • Minimal adverse effects compared to other options

Third-Line Options (if seizures persist):

• Valproate 20-30 mg/kg IV (88% success rate) 2
• Phenytoin 18-20 mg/kg IV (56% success rate) 2
  • Administer at rate not exceeding 1 mg/kg/min
  • Dilute in normal saline (incompatible with glucose solutions)
  • Monitor for hypotension, cardiac dysrhythmias, and purple glove syndrome

Fourth-Line Treatment:

• Phenobarbital 10-20 mg/kg IV (maximum 1,000 mg) 1, 2
  • 58% efficacy in terminating refractory seizures
  • Monitor closely for respiratory depression and hypotension

For Refractory NCSE:

• Transfer to ICU/PICU
• Consider anesthetic doses of medications 4
• Consider immunomodulatory therapy if autoimmune/paraneoplastic etiology is suspected 4

Maintenance Therapy After Resolution

• Lorazepam 0.05 mg/kg (maximum 1 mg) IV every 8 hours for 3 doses
• Levetiracetam 15 mg/kg (maximum 1,500 mg) IV every 12 hours
• Phenobarbital 1-3 mg/kg IV every 12 hours (if used) 1

Monitoring

• Continuous EEG monitoring is essential for at least 24 hours after clinical control 3
• Regular cardiorespiratory monitoring and frequent neurological assessments
• Monitor for medication side effects, especially respiratory depression with benzodiazepines and barbiturates
• Monitor oxygen saturation and blood pressure, particularly when administering phenytoin 2

Important Considerations

• The ESETT trial showed no significant difference in efficacy between levetiracetam (47%), fosphenytoin (45%), and valproate (46%) for status epilepticus 1
• Treatment should be initiated promptly as delay in diagnosis and treatment is associated with worse outcomes 5
• The choice of specific antiseizure medications should consider patient factors such as renal/hepatic function and hemodynamic stability 6
• When multiple antiseizure medications are required, combining different mechanisms of action should be considered 6

Pitfalls and Caveats

• NCSE is often underdiagnosed without EEG monitoring 5
• Clinical detection of NCSE is often impossible with routine neurological evaluations 3
• Outcomes are worse when NCSE is caused by toxic/metabolic derangements or anoxia 2
• Transition from convulsive to non-convulsive status epilepticus is common and requires EEG confirmation of treatment success 4
• Persistent NCSE after apparent control of convulsive status epilepticus occurs in nearly half of patients and requires EEG monitoring for detection 3