Seizures

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

Definition

Seizures are sudden, uncontrolled electrical disturbances in the brain that cause changes in behaviour, movement, sensation, or awareness. They can be provoked (caused by an identifiable trigger) or unprovoked (indicative of epilepsy).

Aetiology

1. Provoked (Acute Symptomatic) Seizures:

  • Fever (febrile seizures in children).
  • Hypoglycaemia or hyperglycaemia.
  • Electrolyte imbalances (hyponatraemia, hypocalcaemia).
  • Head trauma or brain injury.
  • Drug or alcohol withdrawal.
  • Acute infections (meningitis, encephalitis).
  • Stroke or transient ischaemic attack (TIA).

2. Unprovoked (Epileptic) Seizures:

  • Idiopathic epilepsy (genetic predisposition).
  • Structural brain abnormalities (e.g., tumours, congenital malformations).
  • Neurodegenerative diseases (e.g., Alzheimer's disease).
  • Autoimmune encephalitis.

Pathophysiology

  • Imbalance between excitatory (glutamate) and inhibitory (GABA) neurotransmission.
  • Hyperexcitable neurons lead to synchronised bursts of electrical activity.
  • Spread of abnormal electrical activity determines seizure type (focal or generalised).

Risk factors

  • Family history of seizures or epilepsy.
  • History of head trauma.
  • Neonatal complications (hypoxic-ischaemic injury).
  • Previous central nervous system infections.
  • Use of stimulant drugs or alcohol withdrawal.
  • Underlying neurological disorders.

Signs and symptoms

Types of Seizures:

1. Focal Seizures (Originating in One Hemisphere):
  • Focal aware seizures: no loss of consciousness, symptoms depend on the brain area involved.
  • Focal impaired awareness seizures: altered awareness, automatisms (e.g., lip-smacking, hand movements).
2. Generalised Seizures (Involving Both Hemispheres):
  • Tonic-clonic seizures: sudden loss of consciousness, muscle rigidity, rhythmic jerking.
  • Absence seizures: brief staring episodes, common in children.
  • Myoclonic seizures: sudden muscle jerks.
  • Atonic seizures: loss of muscle tone, sudden collapse.

Postictal Symptoms (After a Seizure):

  • Confusion or drowsiness.
  • Headache.
  • Muscle soreness.
  • Temporary weakness (Todd’s paresis).

Investigations

  • Clinical assessment: detailed history, eyewitness account.
  • EEG (Electroencephalogram): detects abnormal electrical activity.
  • MRI brain: identifies structural causes.
  • Blood tests:
    • FBC, U&Es, glucose (rule out metabolic causes).
    • Calcium, magnesium (electrolyte imbalances).
    • Toxicology screen (if substance-related seizure suspected).

Management

1. Acute Seizure Management:

  • Ensure patient safety (move objects away, cushion head).
  • Do not restrain movements.
  • Place in the recovery position after seizure stops.
  • If seizure lasts >5 minutes, consider status epilepticus.

2. Status Epilepticus Management:

  • First-line: IV lorazepam 4 mg.
  • Second-line: IV phenytoin or levetiracetam.
  • If refractory, consider anaesthetic agents (e.g., propofol, midazolam).

3. Long-Term Management:

For Focal Seizures:
  • Carbamazepine or lamotrigine.
For Generalised Seizures:
  • Valproate (avoid in women of childbearing age if possible).
  • Levetiracetam or lamotrigine as alternatives.
For Absence Seizures:
  • Ethosuximide or valproate.

4. Lifestyle Advice and Prevention:

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

5. Specialist Treatment (If Drug-Resistant):

  • Vagus nerve stimulation (VNS).
  • Ketogenic diet for paediatric drug-resistant seizures.
  • Epilepsy surgery in selected cases.
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