Epilepsy

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Epilepsy is a chronic neurological disorder characterised by recurrent, unprovoked seizures due to abnormal electrical activity in the brain.

Aetiology

1. Genetic Causes:

  • Idiopathic generalised epilepsy.
  • Channelopathies (e.g., sodium or potassium channel mutations).

2. Structural Causes:

  • Stroke.
  • Traumatic brain injury.
  • Brain tumours.
  • Cerebral infections (e.g., meningitis, encephalitis).

3. Metabolic and Other Causes:

  • Hypoglycaemia, hyponatraemia.
  • Drug or alcohol withdrawal.
  • Neurodegenerative diseases (e.g., Alzheimer's disease).

Pathophysiology

  • Hyperexcitation and hypersynchronisation of neurons lead to excessive electrical discharges.
  • Imbalance between excitatory (glutamate) and inhibitory (GABA) neurotransmission.
  • Seizures can be focal (localised to one brain region) or generalised (involving both hemispheres).

Risk factors

  • Family history of epilepsy.
  • Head trauma or brain injury.
  • History of stroke or brain infection.
  • Neonatal hypoxia.
  • Neurodevelopmental disorders (e.g., autism, cerebral palsy).

Signs and symptoms

Types of Seizures:

1. Focal Seizures:
  • Focal aware seizures: no loss of consciousness; sensory, motor, or autonomic symptoms.
  • Focal impaired awareness seizures: altered awareness, automatisms (e.g., lip-smacking, hand movements).
2. Generalised Seizures:
  • Tonic-clonic seizures: loss of consciousness, tonic phase (rigidity), clonic phase (jerking movements).
  • Absence seizures: brief loss of awareness, staring episodes, common in children.
  • Myoclonic seizures: sudden jerks of the limbs.
  • Atonic seizures: sudden loss of muscle tone, leading to falls.

Postictal Symptoms:

  • Confusion, drowsiness.
  • Headache.
  • Focal neurological deficits (Todd’s paresis temporary limb weakness).

Investigations

  • Clinical assessment: detailed history, eyewitness account of seizures.
  • EEG (Electroencephalogram): detects abnormal electrical activity.
  • MRI brain: identifies structural abnormalities (tumours, strokes, malformations).
  • Blood tests:
    • FBC, U&Es, glucose, calcium, magnesium (rule out metabolic causes).
    • Toxicology screen if substance-related seizures suspected.

Management

1. Acute Seizure Management:

  • Protect airway: place patient in recovery position.
  • Do not restrain movements.
  • Monitor duration: if seizure >5 minutes, consider status epilepticus.
  • First-line for status epilepticus: IV lorazepam 4 mg.
  • Second-line: IV phenytoin or levetiracetam.

2. Long-Term Management (Anti-Seizure Medication):

Focal Epilepsy:
  • Carbamazepine or lamotrigine (first-line).
Generalised Epilepsy:
  • Valproate (avoid in women of childbearing age unless no alternative).
  • Lamotrigine or levetiracetam if valproate contraindicated.
Absence Seizures:
  • Ethosuximide or valproate.

3. Lifestyle Advice and Safety Measures:

  • Avoid known seizure triggers (e.g., sleep deprivation, alcohol, flashing lights).
  • Driving restrictions (DVLA rules – seizure-free period required before driving).
  • Supervision while swimming or bathing.

4. Non-Pharmacological Treatments:

  • Vagus nerve stimulation (VNS) for refractory epilepsy.
  • Ketogenic diet in paediatric patients with drug-resistant epilepsy.
  • Surgical resection of epileptic focus in selected cases.
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