A Highly Provocative Seizure

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:

Seizuresudden 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:

classification of seizures.PNG

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

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