Updated: 9/27/2020

Seizures

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Snapshot
  • A 16-year-old girl presents to the emergency department with a recent convulsive episode. The mother reports that this episode occured a few hours after awakening, described her movements as myoclonic, and involving the upper extremity. As time progressed, her myoclonus evolved into a generalized tonic-clonic seizure that lasted 3-4 minutes. The patient reported to sleeping only a few hours per night due to upcoming examinations. Physical exam is unremarkable. EEG shows 5-Hz polyspike and slow-wave discharges. (Juvenile myoclonic epilepsy)
Introduction
  • Clinical definition
    • synchronized and high-frequency neuronal depolarization that results in
      • abnormal behavior and patient experience
    • this is different from epilepsy, which can be simply described as
      • a tendency to have recurrent seizures that are unprovoked
        • febrile seizures are not considered to be epilepsy
  • Other definitions
    • ictal
      • during the seizure
    • postictal
      • after the seizure
    • interictal
      • between seizures
    • aura
      • foc
      • for example, patients may describe a rising epigastric visceral sensation in
        • a seizure affecting the medial temporal limbic structures
    • status epilepticus
      • life threatening seizure episode that occurs
        • continuously or in rapid successions
  • Etiology
    • can be divided into provoked and unprovoked causes
      • provoked
        • substance abuse (e.g., cocaine and MDMA)
        • space occupying lesion (e.g., malignancy and abscess)
        • stroke (e.g., ischemic and hemorrhagic)
        • meningitis and encephalitis
        • hypo- or hyperglycemia
        • hyponatremia
        • hypocalcemia
        • hypomagnesemia
        • medication withdrawal (e.g., benzodiazepine and alcohol)
      • unprovoked
        • underlying neurological disorder (e.g., childhood absence epilepsy and neurofibromatosis)
  • Seizure classification
    • classification is based on the International League Against Epilepsy (ILAE)
    • seizures can be initially divided into
      • focal and generalized
Focal Seizures
  • Clinical definition 
    • abnormal neuronal activity in a localized (focal) part of the brain
  • Partial seizures can
    • secondarily generalize
    • be subdivided into
      • simple partial seizures
      • complex partial seizures
 
Focal Seizure Types
Seizure Type
Clinical Features
Focal onset seizures with awareness
  • Consciousness is spared
  • Symptoms are dependent on the anatomical location of the seizure
    • e.g., abnormal shapes or flashes when there is a seizure in the primary visual cortex
  • Typically no postictal deficits in brief simple partial seizures
Focal onset seizures without awareness 
  • Consciousness is impaired
    • this can be complete or mild
  • Symptoms are dependent on the anatomical location of the seizure
  • May have automatisms
  • Most common location is in the
    • temporal lobes
 
Generalized Seizures
  • Clinical definition
    • abnormal neuronal activity in both hemispheres of the brain
  • Generalized seizures
    • is almost always associated with impaired consciousness
    • generalized tonic-clonic (grand mal) seizures is
      • the most common type of generalized seizure
 
Generalized Seizure Types
Seizure Type
Clinical Features
Absence (petit mal seizures)
  • Most commonly occurs in children
  • Can occur many times in a day
  • Brief episodes (~10 seconds) of unresponsiveness
    • parents may report the patient had a blank stare
    • can occur many times in a day
  • No postictal deficits and automatisms
  • Characteristic EEG finding is
    • generalized 3-4-Hz spike and wave discharges
Myoclonic
  • Patients can present with quick and repetitive jerks
Tonic-clonic
  • Typically begins with a tonic phase
    • contraction of all muscles for 10-15 seconds
      • leads to a fall "like a tree"
  • The clonic phase follows the tonic phase
    • rhythmic jerking of the bilateral extremities
  • There are postictal deficits
Tonic
  • Patients can present with stiffening
Atonic
  • Patients can present with "drop" seizures
    • can be mistaken as fainting
 
 

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