Neurology >
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