When do you order an Electroencephalogram (EEG) and start antiepileptics, such as Keppra (levetiracetam) or Dilantin (phenytoin), in the management of Traumatic Brain Injury (TBI)?

EEG and Antiepileptic Management in Traumatic Brain Injury

When to Order EEG in TBI

Routine EEG monitoring and prophylactic antiepileptic drugs are not recommended for all TBI patients. 1

EEG monitoring should be considered in the following specific situations:

• Persistent coma or unexplained decreased mental status
• Clinical signs of seizures
• Patients with risk factors for post-traumatic seizures:
  • Brain contusion
  • Acute subdural hematoma
  • Skull fracture
  • Loss of consciousness or amnesia for more than 24 hours
  • Age over 65 years
  • Craniectomy (which has been identified as a possible risk factor)

Antiepileptic Drug Management in TBI

Primary Prophylaxis

The evidence does not support routine use of antiepileptic drugs (AEDs) for primary seizure prophylaxis in all TBI patients. According to the 2018 guidelines, "prevention of post-traumatic seizures with AEDs cannot be recommended" 1.

However, AED prophylaxis may be considered in patients with specific risk factors:

• Brain contusion
• Acute subdural hematoma
• Skull fracture
• Prolonged loss of consciousness (>24 hours)
• Age over 65 years
• Past history of epilepsy

Choice of Antiepileptic Drug

When prophylaxis is deemed necessary based on risk factors, levetiracetam should be preferred over phenytoin due to its better tolerance profile 1. This recommendation is supported by multiple studies showing:

1. Equivalent efficacy between levetiracetam and phenytoin in preventing early post-traumatic seizures 2, 3
2. Better side effect profile with levetiracetam compared to phenytoin 1
3. Lower total antiepileptic drug and monitoring costs with levetiracetam 3

Duration of Prophylaxis

If prophylactic AEDs are used, they should be administered for 7 days after injury, as this is the period of highest risk for early post-traumatic seizures. Despite this recommendation, studies show that approximately 65% of patients receive prophylactic AEDs for longer than 7 days 4, which is not supported by evidence.

Important Considerations and Pitfalls

1. Avoid prolonged prophylaxis: Evidence only supports short-term (7-day) prophylaxis for early post-traumatic seizures. Continuing AEDs beyond this period without evidence of seizure activity is not recommended.

2. Monitor for side effects: Phenytoin has significant side effects including altered drug metabolism, fever, and requires therapeutic-level monitoring 2. These side effects can potentially worsen neurological outcomes 1.

3. Therapeutic levels: When using phenytoin, ensure weight-based dosing to achieve therapeutic CSF levels. Standard fixed dosing of levetiracetam may not reach therapeutic CSF levels in the acute setting 5.

4. Changing practice patterns: There has been a shift from phenytoin to levetiracetam use in TBI patients since 2008 4, likely due to levetiracetam's better side effect profile and easier administration.

5. EEG findings: Patients on levetiracetam may show higher incidence of seizure tendency on EEG without clinical seizures 2, but the clinical significance of this finding remains unclear.

By following these evidence-based recommendations, clinicians can optimize the management of TBI patients while minimizing unnecessary interventions and potential adverse effects of antiepileptic medications.