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INTRODUCTION

  • Epilepsy is a common neurologic condition in which a person is prone to recurrent epileptic seizures. Epilepsies are characterized by different seizure types, ranging in severity and etiologies often with neurobiological, cognitive, psychological, and social consequences. Status epilepticus (SE) is a neurologic emergency associated with brain damage and death with generalized convulsive status epilepticus (GCSE) being the most common and severe form. It occurs when the length of the continuous seizure activity extends past 5 minutes or time of ongoing seizure activity extends past 30 minutes, after which there is a risk of long-term consequences.

PATHOPHYSIOLOGY

  • Seizures result from excessive excitation or disordered inhibition of neurons, resulting in changes in electrical activity as measured by the electroencephalogram (EEG). Initially, a small number of neurons fire abnormally. Normal membrane conductances and inhibitory synaptic currents then break down, and excitability spreads locally (focal seizure) or more widely (generalized seizure). Epileptic seizures result only when there is also synchronization of excessive neuronal firing.

  • Seizure initiation is likely caused by an imbalance between excitatory (eg, glutamate, calcium, sodium, substance P, and neurokinin B) and inhibitory (γ-aminobutyric acid [GABA], adenosine, potassium, neuropeptide Y, opioid peptides, and galanin) neurotransmission.

  • GCSE is largely caused by glutamate acting on postsynaptic N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate receptors. Sustained depolarization can result in neuronal death.

  • GABAA receptors may become less responsive to endogenous GABA and GABA agonists.

  • Epilepsy etiologies can be classified into six categories: (1) genetic; (2) structural; (3) infectious; (4) metabolic; (5) immune; and (6) unknown.

CLINICAL PRESENTATION

Epilepsy

  • Figure 54-1 shows the International League Against Epilepsy (ILAE) framework for the classification of seizure types.

  • Many patients, particularly those with focal onset seizures with dyscognitive features or generalized tonic–clonic (GTC) seizures, are amnestic to the actual seizure event.

  • Symptoms depend on seizure type and where the abnormal firing occurs. Although seizures can vary between patients, they tend to be stereotyped within an individual.

  • Focal seizures (ie, partial seizures) begin in one hemisphere of the brain, and unless they become secondarily generalized (ie, evolve to a bilateral convulsive seizure), result in an asymmetric seizure. Focal seizures manifest as alterations in motor functions (eg, twitching or shaking), sensory (eg, numbness or tingling) or somatosensory symptoms, aberrations in behavior, or automatisms. Focal seizures without dyscognitive features (formerly called simple partial seizures) are associated with no impairment of consciousness. In focal seizures with dyscognitive features (formerly called complex partial seizures), there is impairment of consciousness and awareness and no memory of the event.

  • Absence seizures generally occur in young children or adolescents and exhibit a sudden onset, interruption of ongoing activities, a blank stare, and possibly a brief upward rotation of the eyes. There is only a very brief (seconds) period of altered consciousness. Absence seizures have a characteristic two to four cycles per second spike and slow-wave ...

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