Epilepsy

“Paroxysmal transient disturbances of nervous system function resulting from abnormal electrical activity of the brain”

Aetiology & Risk Factors

• Children
  • Inherited syndromes
  • Congenital brain malformations
  • Infection
  • Head trauma
  • Lack of oxygen during birth
• Young Adults
  • Head trauma
• Middle Age
  • Stroke
  • Tumours
  • Head trauma
• Old Age
  • Stroke
  • Alzheimer’s
  • Other degenerative diseases
• Chromosomal syndromes that can cause seizures
  • 22q deletion syndrome
  • Wolf-Hirschhorn syndrome – 4p16.3
  • 1p36 deletion
• Metabolic Diseases
  • Hypoglycaemia
  • Acidosis
  • Vitamins
  • Peroxisomal biogenesis disorders
  • Glycosylation disorders
  • Neuronal ceroid lipofuscinosis
  • Metal and metal cofactor deficiency
  • Neurotransmitter metabolism
  • Lysosomal storage diseases
• Mitochondrial Diseases
  • MELAS
  • MERRF

Pathophysiology

• The sudden imbalance between the excitatory and inhibitory forces within the network of cortical neurons in favour of sudden-onset excitation

Clinical Presentation

• Focal Seizures
  • Simple/aware (patient is conscious) – focal motor, sensory, autonomic or psychic symptoms, no post-ictal symptoms
  • Complex/impaired awareness (patient loses consciousness) – awareness impaired either at seizure onset or following a simple partial aura; most commonly from the temporal lobe, in which post-ictal confusion is a feature
  • Evolving to bilateral convulsive seizure – in 2/3 patients with partial seizures, the electrical disturbance which starts focally spreads widely to cause a generalised seizure, which is typically convulsive
  • Localising features of focal seizures
    • Temporal lobe – automatisms (lip-smacking, chewing, swallowing, fumbling, fiddling, grabbing), dysphasia, déjà vu, jamais vu, emotional disturbance, hallucinations of smell/taste/sound, delusional behaviour, bizarre associations
    • Frontal lobe – motor features such as posturing or peddling movements of the legs, jacksonian march, motor arrest, subtle behavioural disturbances, dysphasia/speech arrest, Todd’s palsy post ictally
    • Parietal lobe – sensory disturbances (tingling, numbness, pain – rare), motor symptoms (precentral gyrus)
    • Occipital lobe – visual phenomena (spots, lines, flashes)

• Generalised Seizures
  • Absence seizures (previously known as petit-mal) – brief <10s pauses, e.g. suddenly stop talking mid-sentence, and then carry on where left off; presents in childhood
  • Tonic-clonic seizures (previously known as grand-mal) – loss of consciousness, limbs stiffen (tonic), then jerk (clonic), may also have one without the other, post ictal confusion and drowsiness
  • Myoclonic seizures – sudden jerk of limb, face or trunk, patient may be thrown suddenly to the ground, or have a violently disobedient limb
  • Atonic (akinetic) seizures – sudden loss of muscle tone causing a fall (no LOC)
  • Infantile spasms – commonly associated with tuberous sclerosis

Investigations

• Look for provoking causes
• Consider an EEG
• Emergency EEG if non-convulsive status
• MRI – structural lesions
• Drug levels if the patient is on anti-epileptics
• Drug screen
• LP if an infection is suspected

Management

• Counselling about swimming, driving, heights, employment, insurance, conception – must contact DVLA and avoid driving until seizure-free for >1 yr
• Psychological therapies – relaxation, CBT (adjunct only)
• Surgical intervention – can be considered if a single epileptogenic focus can be identified, 70% chance of seizure resolution, risk of causing focal defects
• Vagal nerve stimulation/deep brain stimulation (DBS)

• Medication:

Seizure Type	First Line Drugs	Second Line Drugs
Partial	Carbamazepine Lamotrigine Oxcarbazepine Sodium Valproate	Clobazam Gabapentin Levetiracetam Pregabalin Tiagabine Topiramate Zonisamide
Tonic-clonic	Carbamazepine Lamotrigine Sodium Valproate	Clobazam Levetiracetam Oxcarbazepine Topiramate
Myoclonic	Sodium Valproate	Clonazepam Levetiracetam Lamotrigine Topiramate
Absence	Ethosuximide Sodium Valproate	Clonazepam Lamotrigine
Atonic	Sodium Valproate Lamotrigine Clonazepam	Clobazam Ethosuximide Levetiracetam Topiramate

Complications

• SUDEP – more common in uncontrolled epilepsy, or nocturnal seizure-associated apnoea or asystole
• Medications and pregnancy – many are teratogenic