Seizure, Adult

Basics

Description

  • Generalized seizures:
    • Abnormal neuronal activity in both cerebral hemispheres with impaired awareness
    • Can be further characterized with motor-onset (tonic–clonic, clonic, tonic, myoclonic, myoclonic–tonic–clonic, myoclonic–atonic, atonic, epileptic spasms) or nonmotor (typical absence, atypical absence, myoclonic absence, absence with eyelid myoclonia) symptoms
    • Classically tonic–clonic seizures: Impaired awareness, muscle rigidity (tonic), rhythmic jerking movements (clonic)
    • Absence seizures: Altered consciousness but no postural tone change; can have brief twitches (myoclonus)
  • Focal seizures:
    • Usually involves 1 area within 1 cerebral hemisphere, which may progress to bilateral involvement
    • More likely to be secondary to localized structural lesion
    • Can be further classified as “aware” or with “impaired awareness”
    • Motor-onset (automatisms, atonic, clonic, epileptic spasms, hyperkinetic, myoclonic, tonic)
    • Nonmotor onset (autonomic, behavior arrest, cognitive, emotional, sensory) symptoms
  • Classification of seizure with “unknown onset” is used to describe unwitnessed start of seizure activity
  • Status epilepticus:
    • Seizure lasting longer than 5 min or recurrent seizures without return to baseline mental status between events
    • Nonconvulsive status epilepticus may present in >8% of hospitalized patients with prolonged decreased mental status
    • Life-threatening emergency, mortality approaching 30% if seizure lasts >1 hr
    • At least 50% of patients presenting to ED in status do not have a history of seizures
  • Special populations:
    • HIV: Mass lesions, encephalopathy, herpes zoster, toxoplasmosis, Cryptococcus, neurosyphilis, meningitis
    • Neurocysticercosis: CNS infection of tapeworm Taenia solium, major cause of provoked seizures in developing world
    • Pregnancy >20 wk of gestation or <6 wk postpartum: Eclampsia (hypertension, edema, proteinuria, seizures)
    • Alcohol withdrawal seizures: Peak within 24 hr of last drink, rarely progress to status epilepticus
  • 1% of ED visits annually (approximately 1 million)
  • 8–10% lifetime risk of symptomatic seizure
  • Patients with a single seizure have up to a 45% risk of recurrent seizure within 2 yr

Etiology

  • Hypoxia
  • Hypertensive encephalopathy
  • Eclampsia
  • Infection:
    • Meningitis
    • Abscess
    • Encephalitis
  • Vascular:
    • Stroke (ischemic or hemorrhagic)
    • Subdural hematoma
    • Epidural hematoma
    • Subarachnoid hemorrhage
    • Arteriovenous malformation
  • Structural:
    • Primary or metastatic neoplasm
    • Degenerative disease (eg, multiple sclerosis)
    • Lesion from previous trauma or stroke
  • Metabolic:
    • Electrolytes (Hypo/hypernatremia, hypocalcemia)
    • Hypo/hyperglycemia
    • Uremia
  • Toxins/drugs including:
    • Lidocaine
    • Tricyclic antidepressants
    • Salicylates
    • Isoniazid
    • Cocaine
    • Alcohol withdrawal
    • Benzodiazepine withdrawal
  • Congenital abnormalities
  • Idiopathic
  • Trauma

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