Seizure Disorders and Epilepsy

Definitions & Classification - Seizure Spectrum

• Seizure: Transient neurological dysfunction from abnormal, excessive/synchronous brain neuronal activity.
• Epilepsy: Enduring predisposition to seizures. Diagnosis:
  • ≥2 unprovoked seizures >24h apart.
  • 1 unprovoked seizure + >60% recurrence risk over 10 yrs.
  • Epilepsy syndrome diagnosis.
• Status Epilepticus (SE): Seizure >5 min OR ≥2 seizures without full recovery between.

ILAE 2017 Classification Highlights:

• Focal Onset: One hemisphere.
  • Awareness: Aware / Impaired.
  • Type: Motor / Non-motor.
  • Progression: Focal to Bilateral Tonic-Clonic.
• Generalized Onset: Bilateral networks.
  • Motor: Tonic-clonic, Myoclonic, Atonic, etc.
  • Non-motor: Absence (Typical, Atypical).
• Unknown Onset: Insufficient data. Motor / Non-motor.

⭐ Typical absence seizures classically show 3 Hz spike-and-wave pattern on EEG.

Etiology & Pathophysiology - Brain's Electrical Storm

• Core Imbalance: ↑Excitatory (e.g., Glutamate) vs. ↓Inhibitory (e.g., GABA) neurotransmission → neuronal hyperexcitability & hypersynchronization.
• Key Pathophysiology:
  • 📌 Paroxysmal Depolarizing Shift (PDS): Key event; prolonged neuronal depolarization.
  • Failure of surround inhibition → seizure spread.
  • Kindling: Repeated subthreshold stimuli lower seizure threshold.
• Major Etiologies:
  • Genetic: Channelopathies (Na+, K+).
  • Structural: Trauma, stroke, tumor, infection sequelae (neurocysticercosis), cortical dysplasia.
  • Metabolic: ↓Na+, ↓Ca2+, ↓Glucose, hypoxia, uremia, Vit B6 def. (infants).
  • Immune: Autoimmune encephalitis (e.g., anti-NMDA).
  • Infections (acute): Meningitis, encephalitis.
  • Febrile: Common in children.
  • Unknown.

⭐ Febrile seizures are the most common seizure type in children (typically 6 months to 5 years); simple febrile seizures generally have an excellent prognosis and do not require daily AEDs.

Clinical Approach & Diagnosis - Epilepsy Evidence Hunt

• History:
  • Event: Aura, LOC, motor features (tonic, clonic), automatisms, duration.
  • Post-event: Post-ictal confusion, Todd's paresis.
  • Triggers: Sleep deprivation, alcohol, stress.
  • Risk factors: Febrile seizures, CNS infection, head trauma, family Hx.
• Examination: General (neurocutaneous markers), Neurological (focal deficits).
• Investigations:
  • Bloods: Glucose, Ca$^{2+}$, Mg$^{2+}$, Na$^{+}$, renal/liver function, toxicology.
  • EEG: Standard, sleep-deprived; interictal discharges (spikes); provocative tests (hyperventilation, photic).
  • Neuroimaging:

    ⭐ MRI is the neuroimaging modality of choice for new-onset unprovoked seizures in adults to identify potential structural epileptogenic lesions.

    • CT: Emergency (trauma, bleed) or if MRI unavailable.
  • LP: If CNS infection suspected.

Treatment Strategies - Calming the Current

• Goal: Stop acute seizures, prevent recurrence, minimize side effects.
• Status Epilepticus (SE) Management: Rapid, stepwise approach.

• Chronic Epilepsy Management:
  • Monotherapy preferred; titrate slowly.
  • AED choice: 📌 Seizure type, Patient profile, Efficacy, Adverse effects, Kinetics (SPEAK). Consider drug interactions.
  • Common AEDs: Valproate (broad-spectrum), Levetiracetam (well-tolerated), Lamotrigine (focal, generalized), Carbamazepine (focal).
  • Consider surgery for drug-resistant epilepsy.

⭐ Intravenous benzodiazepines (e.g., lorazepam, diazepam) are the first-line treatment for acute seizures and status epilepticus, followed by loading with a non-benzodiazepine AED like fosphenytoin, valproate, or levetiracetam.

High‑Yield Points - ⚡ Biggest Takeaways

• Status epilepticus is a neurological emergency: seizure >5 min or ≥2 seizures without full recovery between them.
• Febrile seizures are common in children (6 months - 5 years); typically benign, differentiate simple vs. complex.
• Absence seizures show characteristic 3 Hz spike-and-wave pattern on EEG; ethosuximide is first-line treatment.
• Focal seizures (aware/impaired awareness) originate in one cerebral hemisphere; postictal Todd's paralysis can occur.
• Generalized tonic-clonic seizures (GTCS) involve abrupt loss of consciousness, tonic stiffening, and clonic jerking phases.
• Juvenile Myoclonic Epilepsy (JME) typically presents with morning myoclonic jerks, often GTCS; lifelong valproate is a key treatment (caution in females).
• Lamotrigine and levetiracetam are broad-spectrum anti-epileptic drugs, generally considered safer options during pregnancy if needed.