Pathology - Epilepsy

I. Definition & Epidemiology:

• Epilepsy: A neurological disorder characterized by recurrent, unprovoked seizures resulting from abnormal brain electrical activity.
• Prevalence: Affects approximately 1% of the population.

II. Etiology (Causes):

• Idiopathic: In many cases, no identifiable cause is found.
• Secondary Causes: Epilepsy can be associated with:
  • Structural lesions: Trauma, tumors (neoplasms), brain malformations.
  • Metabolic disorders: Alcohol abuse, electrolyte imbalances.
  • Infections: Various infections affecting the brain.

III. Seizure Types:

Seizures are categorized based on their clinical presentation and the involvement of brain hemispheres:

A. Partial Seizures (Focal Seizures): Originate in a specific area of one brain hemisphere.

• Simple Partial Seizures: Consciousness remains intact. Examples include focal motor seizures (localized muscle twitching or jerking).
• Complex Partial Seizures: Consciousness is impaired. Examples include staring spells, automatisms (repetitive, seemingly purposeless movements), and altered awareness.

B. Generalized Seizures: Involve both hemispheres simultaneously; consciousness is always impaired.

• Absence Seizures ("Petit Mal"): Brief (<10 seconds) periods of unresponsiveness, often appearing as a momentary pause in activity (e.g., stopping mid-sentence). Common in childhood absence epilepsy.
• Tonic-Clonic Seizures ("Grand Mal"): Characterized by a sudden loss of consciousness followed by stiffening (tonic phase) and rhythmic jerking (clonic phase) of the limbs.
• Myoclonic Jerks: Sudden, brief, involuntary muscle contractions, often affecting the limbs. Common in juvenile myoclonic epilepsy.

IV. Specific Epilepsy Syndromes:

These are characterized by specific seizure types and age of onset:

• Temporal Lobe Epilepsy:
  • Onset: Late childhood/adolescence.
  • Seizure Types: Primarily complex partial seizures (e.g., epigastric aura – strange feeling in the gut; déjà vu; olfactory hallucinations – strange smells), often progressing to secondary generalized tonic-clonic seizures.
  • Cause: Typically an epileptogenic focus (abnormal brain activity) in the temporal lobe.
• Childhood Absence Epilepsy:
  • Onset: Ages 4-12.
  • Seizure Types: Primarily absence seizures. Some children may also experience tonic-clonic seizures.
  • Etiology: Idiopathic (no clear cause).
• Juvenile Myoclonic Epilepsy:
  • Onset: Ages 8-20.
  • Seizure Types: Myoclonic jerks are most common, but absence and tonic-clonic seizures can also occur.
  • Etiology: Idiopathic (no clear cause).

V. Key Differences Summarized: