Seizures and Epilepsy Lecture Notes

May 28, 2024

Seizures and Epilepsy

Introduction

  • Seizure Definition: Abnormal excessive synchronous electrical activity in the central nervous system leading to outward manifestations.

Causes of Seizures

Mnemonic: VITAMIN D and E

  1. Vascular Causes:
    • Acute ischemic stroke
    • Intracerebral hemorrhage
    • Subarachnoid hemorrhage
    • Hypertensive encephalopathy / PRES (Posterior Reversible Encephalopathy Syndrome)
    • Severe anoxic brain injuries
  2. Infectious Causes:
    • Meningitis
    • Encephalitis
    • Brain abscess
  3. Traumatic Causes:
    • Epidural hematoma
    • Subdural hematoma
  4. Autoimmune Causes:
    • Systemic lupus erythematosus (SLE)
    • Paraneoplastic syndromes
  5. Metabolic Causes:
    • Thiamine (Vitamin B1) deficiency
    • Hypoglycemia (and less common hyperglycemia)
    • Hyponatremia (more common) / Hypernatremia
    • Hypocalcemia
    • Hypomagnesemia
    • Hypophosphatemia
    • Uremia
    • Liver failure (Ammonia buildup)
    • Hyperthyroidism
  6. Idiopathic Causes:
    • Defined as epilepsy (≥ 2 unprovoked seizures >24 hours apart or 1 unprovoked seizure with a 60% recurrence rate)
    • Non-compliance or sub-therapeutic dose of anti-epileptic drugs
    • Epilepsy syndromes (West syndrome, Lennox-Gastaut syndrome, Juvenile myoclonic epilepsy)
  7. Neoplasia:
    • Glioblastoma multiforme
    • Meningioma
    • Metastatic brain tumors
  8. Drug Causes: Mnemonic: OTIS CAMPBELL
    • Opioids, Tricyclic antidepressants, Anticholinergics, Isoniazid, Salicylates, Cocaine, Cefepime, Amphetamines, Metronidazole, Penicillins, Benzodiazepine withdrawal, Bupropion, Ethanol withdrawal, Lithium
  9. Eclampsia:
    • Pregnant women
    • High blood pressure
    • Seizures

Other Causes

  • Fevers (esp. children with Roseola)
  • Genetic disorders

Pathophysiology

  • Increased stimulatory glutamate pathway (NMDA, AMPA receptors → more cations → depolarization → action potentials)
  • Decreased inhibitory GABA pathway (GABA-A receptors → chloride ions → hyperpolarization → decreased action potentials)
  • Focal seizures vs. generalized seizures
    • Focal: One hemisphere
    • Generalized: Bilateral hemispheres

Clinical Features

Phases of Seizure

  1. Trigger: Stress, sleep deprivation, bright lights/sounds, vitamin D and E causes
  2. Aura: Deja vu, impending fear, nausea, automatisms (e.g., rapid blinking, chewing, lip smacking)
  3. Ictal Event: Visible seizure activity (focal or generalized)
  4. Post-ictal Phase: Confusion, lethargy, amnesia, Todd's paralysis

Types of Seizures

Focal Seizures

  • Motor: Tonic, clonic, myoclonic, Jacksonian march (distal to proximal spread)
  • Sensory: Pain, paresthesias, visual/auditory/olfactory/gustatory hallucinations
  • Autonomic: Tachycardia, hypertension, urinary incontinence, salivation, sweating
  • Psychological: Emotional changes, hypersexual behavior, deja vu, depersonalization, derealization

Generalized Seizures

  • Motor: Tonic-clonic (Grand mal), Atonic, Clonic, Tonic, Myoclonic
    • Features: Respiratory cry, up gaze, pooling of oral secretions, tongue biting, incontinence, tachycardia, hypertension
  • Non-motor: Absence (Petit mal)
    • Features: Staring, daydreaming, rapid blinking, lip smacking, no post-ictal state
    • Diagnostic Indicator: EEG shows 3 Hz spike and wave pattern

Diagnosis

  • History of Seizures: Assess AED (Anti-Epileptic Drug) levels
    • If low: Increase dose
    • If normal: Adjust or switch AED
  • First-time Seizure:
    • Vascular: CT, MRI, Lumbar puncture
    • Infectious: CT, MRI, Lumbar puncture, Blood cultures, CBC
    • Trauma: CT scan for hematomas
    • Autoimmune: Autoimmune panel, CT chest/abdomen/pelvis
    • Metabolic: Check B1, glucose, BMP + Mg/Phos, TSH with reflex, ammonia, liver function
    • Idiopathic: Evaluate AED compliance
    • Neoplasia: CT, MRI with contrast
    • Drugs: Review med list, toxicology screen
    • Eclampsia: Urine/serum beta HCG
    • Others: Temperature, genetic testing
  • Additional Labs: CK, Lactate, Prolactin, Troponin, EKG
  • EEG: Essential to check for abnormal electrical activity

Treatment

  • Initial Management: ABCs (Airway, Breathing, Circulation), reverse easy causes, benzodiazepines
  • Status Epilepticus:
    • Seizure > 5 mins or multiple seizures without recovery
    • ABCs, reverse easy causes, benzodiazepines (Lorazepam IV, Midazolam IM)
    • Proceed with AED loading (Levetiracetam, Phenytoin, Fosphenytoin, Valproate)
    • Continue with IV anti-epileptics (Propofol, Midazolam, Ketamine, Pentobarbital)
    • Add maintenance doses of AED
    • Consider ketogenic diet and further workup if seizures persist
  • Note: Continual assessment and management based on patient status and underlying cause