II. 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

III. Causes: Non-Epileptic Causes of Seizure

  1. Idiopathic (most common, accounts for >70%)
    1. Isolated unprovoked, non-epileptic Seizure
  2. Neurogenic
    1. Brain Tumor
    2. Cerebral dysgenesis
    3. Cerebrovascular degenerative disorders
    4. Migraine Headache
    5. Movement Disorder
    6. Hypertensive Encephalopathy (Posterior Reversible Encephalopathy Syndrome or PRES)
    7. Head Trauma
      1. Cerebral Contusion
      2. Intracranial Hemorrhage
      3. Diffuse Axonal Injury
  3. Cardiogenic
    1. Syncope
    2. Transient Ischemic Attack
    3. Arrhythmia
    4. Sick Sinus Syndrome
  4. 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
  5. 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)
  6. Infectious disease
    1. Gastroenteritis (Rotavirus, Shigella)
    2. Gram NegativeSepsis
    3. Viral Meningitis or Viral Encephalitis
    4. Bacterial Meningitis
    5. Brain Abscess
    6. Syphilis
    7. Central nervous system Parasite
      1. Taenia solium (Neurocysticercosis)
      2. Entamoeba histolytica (Amoebiasis)
      3. Echinococcus species (Hydatid Disease)
  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. Hypoxia
    5. Psychogenic Nonepileptic Seizure (or Pseudoseizure)
    6. Sleep Disorder

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

  1. Subtherapeutic Antiepileptic Drug
  2. Medications (especially if in overdosage)
    1. See Toxin-Induced Seizure Causes
    2. Antipsychotics (esp. Clozapine, Chlorpromazine)
      1. Avoid high dose, or in those with Seizure disorder or brain disorder
    3. Antibiotics (primarily with high doses, or if not adjusted for renal Impairment)
      1. Beta-lactam antibiotics (e.g. Penicillins)
      2. Cephalosporins
      3. Quinolones (e.g. Ciprofloxacin)
    4. Bupropion (Wellbutrin)
      1. Do not exceed maximum dose
      2. Avoid in Eating Disorder (e.g. Bulimia, Anorexia), Seizure disorder, electrolyte disturbance
    5. Cyclosporine (Sandimmune)
    6. Oral HypoglycemicOverdose (e.g. Sulfonylurea Overdose)
    7. Interferon
    8. Isoniazid (INH)
    9. Lithium
    10. Local Anesthetic Systemic Toxicity (LAST Reaction)
    11. Meperidine (Demerol)
    12. Tacrolimus
    13. Theophylline and other Methylxanthines
    14. Tramadol (Ultram)
      1. Avoid combinations with Alcohol or other agents predisposing to Seizure (e.g. Bupropion)
    15. Tricyclic Antidepressants
    16. Quinolone antibiotics
  3. Drug Withdrawal
    1. Alcohol Withdrawal
    2. Benzodiazepine Withdrawal
    3. Cocaine withdrawal
    4. Barbiturate withdrawal
    5. Meperidine withdrawal
  4. Drug or Metal toxicity
    1. Cocaine
    2. Phencyclidine
    3. Sympathomimetics
    4. D-Amphetamine
    5. Nitrous Oxide
    6. Acetylcholinesterase Inhibitor
    7. Organophosphate Poisoning (e.g. Pesticides)
    8. Mercury Poisoning
    9. Lead Poisoning
    10. Intravenous Contrast material
    11. Camphor
    12. Carbon Monoxide Poisoning

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

VI. 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]

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