Today we discussed a case of a patient found to have focal, motor seizure symptoms who was eventually found to have a frontal tumor with vasogenic egema that is likely a metastases from a lung malignancy.

We first defined the following:

Seizure: sudden change in behavior caused by electrical hypersynchronization of neuronal networks in the cerebral cortex

There are two aspects of seizure classification that are important to consider: the cause/setting of the seizure and then the location/type of seizure.

Cause/Setting of Seizure

• Acute Symptomatic – seizure that occurs in close proximity with a brain or systemic insult (25-30% of firs seizures)
  • Brain
    • Subdural hematoma
    • SAH
    • TBI
    • Hypoxic-ischemic injury
    • Brain abscesses
    • Meningitis/encephalitis
  • Systemic
    • Alcohol Withdrawal
    • Drug Intoxication
    • Hyponatremia/Hypernatremia
    • Hypomagnesemia
    • Hypocalcemia
    • Hypoglycemia
    • Nonketotic hyperglycemia
    • Uremia
    • Hyperthyroidism
    • Dialysis Disequilibrium Syndrome
    • Porphyria
• Unprovoked – unknown etiology OR one that occurs due to a preexisting brain lesion or progressive nervous system disorder. the latter is referred to as remote symptomatic seizures.
  • medial temporal lobe epilepsy
  • Poststroke
  • Primary or metastatic brain tumors
  • Vascular malformations
  • Prior CNS infection
  • Head injury
  • Neurodegenerative dementia

Types/Location of Seizure

We reviewed the revised 2017 International League Against Epilepsy Classification:

When Do We Get Neuroimaging?

• Short answer: ALL patients with a first time seizure should have neuroimaging to evaluate for a culprit structural abnormality (some guidelines present some rare exceptions but this should be deferred to the experts)
• MRI is preferred due to superior sensitivity and results sometimes need to be interpreted with caution as some findings may be non-specific and not related to the index event
• In urgent cases start with a head CT and then in most cases an MRI (i.e an intracranial lesion is suspected OR new focal deficits OR persistently altered mental state, fever, persistent headache, focal-onset seizure, history of head trauma, malignancy, immunocompromise, alcoholism, anticoagulation or bleeding diathesis)
• Per UTD, deferred outpatient MRI from the ED is mentioned in patients who have a normal neurologic examination but only if they have a normal CT And reliable follow up can be ensured (systemic limitations on MRI scheduling may not make this recommendation feasible for every situation

When Should We Start Antiepileptics?

• Short answer: it depends
• Acute symptomatic seizures in the critically ill
  • IV AEDs should be started to prevent recurrent seizures and prevent further destabilization
• Acute symptomatic seizures provoked by metabolic derangements
  • they may still be at risk for short term seizure recurrence particularly if the metabolic process may take time to resolve – therefore short-term AED use could be considered
• First unprovoked seizure with a full return to baseline
  • this is the controversial scenario
  • 1/3 of these patients will have a recurrent seizure within 5 years and the risk is increased 2-2.5x in any of the following factors
    • Epileptiform abnormalities on interictal EEG
    • Remote symptomatic case by history or imaging (i.e structural brain abnormality)
    • Abnormal neurologic examination, including focal findings or intellectual disability
    • A first seizure that occurs during sleep
  • In patients with the above risk factors, initiation of AEDs suggested in most patients
  • In patients without the above risk factors, care is individualized and specific to the risks/benefits in your specific patient