II. Definitions

  1. Provoked Seizure (Acute Symptomatic Seizure, Situation-Related Seizure)
    1. Acute Central Nervous System insult as a cause of Seizure
    2. May not persist after cause is removed (or acute phase resolves)
    3. Contrast with unprovoked Seizure (Epilepsy) which persists

III. Causes: New Onset Secondary Seizure Causes by age

  1. Age under 10 years
    1. Febrile Seizure (under age 5 years)
    2. Idiopathic
    3. Congenital
    4. Birth Injury
    5. Head Trauma (including due to Child Abuse)
    6. Gastroenteritis (Rotavirus, Shigella)
    7. Metabolic disorder
      1. Hypoglycemia
      2. Hyponatremia (most common cause in afebrile children under age 2 years)
      3. Hypocalcemia
      4. Hypomagnesemia
  2. Age 10 to 40 years
    1. Idiopathic
    2. Head Trauma
    3. Pre-existing focal brain disease
    4. Drug Withdrawal (e.g. Alcohol Withdrawal)
  3. Age 40 to 60 years
    1. Brain Tumor
    2. Head Trauma
  4. Age over 60 years
    1. Prior Cerebrovascular Accident (32%)
    2. Brain Tumors (14%)
    3. Subdural Hematoma
    4. CNS Infection (Meningitis or Encephalitis)
    5. Alzheimer's Dementia
    6. Metabolic abnormalities
      1. Uremia
      2. Hyperglycemia or Hypoglycemia
      3. Hyponatremia
      4. Alcohol Withdrawal

IV. Causes: Non-Epileptic Causes of Seizure

  1. Idiopathic (most common, accounts for >70%)
    1. Isolated unprovoked, non-epileptic Seizure
  2. Neurogenic
    1. Brain Tumor (primary or metastatic)
    2. Cerebral dysgenesis
    3. Migraine Headache
    4. Movement Disorder
    5. Hypertensive Encephalopathy (Posterior Reversible Encephalopathy Syndrome or PRES)
    6. Arteriovenous Malformation
    7. Cerebrovascular Accident
    8. Intracranial Lymphoma
    9. Head Trauma
      1. Cerebral Contusion
      2. Intracranial Hemorrhage
      3. Diffuse Axonal Injury
      4. Neurosurgery
  3. Infectious disease
    1. Gastroenteritis (Rotavirus, Shigella)
    2. Gram NegativeSepsis
    3. Brain Abscess
    4. Syphilis
    5. Viral Meningitis or Viral Encephalitis
    6. Bacterial Meningitis
    7. Tuberculosis
    8. Prion Disease (e.g. Creutzfeldt-Jakob Disease)
    9. Central Nervous SystemParasite
      1. Taenia solium (Neurocysticercosis)
      2. Entamoeba histolytica (Amoebiasis)
      3. Echinococcus species (Hydatid Disease)
      4. Toxoplasma gondii (Toxoplasmosis)
  4. Cardiopulmonary
    1. Syncope
    2. Transient Ischemic Attack
    3. Arrhythmia
    4. Sick Sinus Syndrome
    5. Hypoxia
  5. Electrolyte
    1. Hypocalcemia
    2. Hyponatremia (Water Intoxication)
      1. Most common cause in afebrile children under age 2 years
      2. May also be caused by Water Intoxication in adults
    3. Hypomagnesemia
    4. Hyperosmolarity
    5. Hypercarbia
  6. Metabolic disorders
    1. Hypoglycemia
    2. Adrenal Insufficiency (Addison Disease)
    3. Hyperthyroidism (Thyroid Storm)
    4. Hypothyroidism
    5. Vitamin B6 deficiency (Pyridoxine deficiency)
    6. Acute Renal Failure (Uremia)
    7. Acute Liver Failure
    8. Inborn Errors of Metabolism (infants)
    9. Porphyria
  7. Miscellaneous
    1. Febrile Seizure
    2. Ecclampsia
      1. Pregnancy after 20 weeks to 6 weeks postpartum
      2. Most Seizures (>80%) are >2 days after delivery
    3. Hyperthermia
    4. Psychogenic Nonepileptic Seizure (or Pseudoseizure)
    5. Sleep Disorder (esp. causing sleep deprivation)
    6. Celiac Disease
    7. Sarcoidosis
    8. Systemic Lupus Erythematosus

V. Causes: Medications and Drugs (and their withdrawal)

  1. Subtherapeutic Antiepileptic Drug
  2. Medications (especially if in overdosage)
    1. See Toxin-Induced Seizure Causes
    2. Antibiotics (primarily with high doses, or if not adjusted for renal Impairment)
      1. Beta-lactam antibiotics (e.g. Penicillins)
      2. Carbapenems
      3. Cephalosporins
      4. Quinolones (e.g. Ciprofloxacin)
      5. Isoniazid (INH)
    3. Immunologic Agents
      1. Cyclosporine (Sandimmune)
      2. Interferon
      3. Tacrolimus
    4. Opioid Analgesics
      1. Fentanyl
      2. Meperidine (Demerol)
      3. Intrathecal Morphine (or epidural Morphine)
      4. Tramadol (Ultram)
        1. Avoid combinations with Alcohol or other agents predisposing to Seizure (e.g. Bupropion)
    5. Psychiatric Agents
      1. Atomoxetine (Strattera)
      2. Antipsychotics
        1. Avoid high dose, or in those with Seizure Disorder or brain disorder
        2. Chlorpromazine
        3. Clomipramine (Anafranil)
        4. Clozapine
      3. Baclofen (Lioresal)
      4. Bupropion (Wellbutrin)
        1. Do not exceed maximum dose
        2. Avoid in Eating Disorder (e.g. Bulimia, Anorexia), Seizure Disorder, Electrolyte disturbance
      5. Lithium
      6. Trazodone
      7. Tricyclic Antidepressants
      8. Venlafaxine (Effexor)
      9. Zolpidem (Ambien)
    6. Miscellaneous
      1. Antihistamines (esp. first generation)
      2. Decongestants
      3. Theophylline and other Methylxanthines
  3. Drug Withdrawal
    1. Alcohol Withdrawal
    2. Benzodiazepine Withdrawal
    3. Cocaine withdrawal
    4. Barbiturate withdrawal
    5. Meperidine withdrawal
  4. Drug or Metal toxicity
    1. Oral HypoglycemicOverdose (e.g. Sulfonylurea Overdose)
    2. Local Anesthetic Systemic Toxicity (LAST Reaction)
    3. Cocaine Intoxication
    4. PhencyclidineIntoxication
    5. Sympathomimetics
    6. D-Amphetamine
    7. Nitrous Oxide
    8. Acetylcholinesterase Inhibitor
    9. Organophosphate Poisoning (e.g. Pesticides)
    10. Mercury Poisoning
    11. Lead Poisoning
    12. Intravenous Contrast material
    13. Camphor
    14. Carbon Monoxide Poisoning

VI. Differential Diagnosis: Other Events that may appear to be Seizure

VII. References

  1. Nocera, Valente, Amanullah (2018) Crit Dec Emerg Med 32(11): 3-9
  2. (2017) Presc Lett 24(8): 47-8
  3. Liu (2017) Am Fam Physician 96(2): 87-96 [PubMed]
  4. Rowland (2022) Am Fam Physician 105(5): 507-13 [PubMed]

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