Epilepsy Flashcards
What is Epilepsy ?
Epilepsy is a chronic condition of repeated seizures
What are Seizures ?
Seizures are abnormal, excessive or synchronous neuronal activity in the brain
Difference between seizures and epilepsy ?
Seizures are the event (or symptom), epilepsy is the disorder
What is Status epilepticus?
Status epilepticus is a prolonged seizure or when seizures recur frequently enough to prevent recovery between episodes (duration 20-30 minutes) – a medical emergency
What is the fraction of people with epilepsy that have a family member with it?
Around 1/3 people
70 % of epilepsy cases arise due to ?
Genetic factors but often with complex inheritance
Only 1 % of all epilepsy cases are ?
Single-gene epilepsies (with simple genetic inheritance)
The remaining 30% of epilepsy cases are due to?
- Injury
- Stroke
- Tumor
- Birth defects
- Infection and autoimmune diseases
Examples of epilepsy syndromes ?
- Dravet syndrome
- Benign Rolandic Epilepsy (i.e. w/ centrotemporal spikes)
- Landau Kleffner syndrome (LKS)
- Rasmussen’s syndrome
- West syndrome
What could be triggers of seizures ?
- Lack of sleep
- Drugs/alcohol
- Missing meals
- Fever
- Not taking medications
- Flashing lights
- Stress
- Monthly periods
What seizure types are not considered part of epilepsy according to the International
League against Epilepsy (ILAE)?
- Febrile seizures (0.5 – 6 years old)
- Alcohol-withdrawal seziures
- Metabolic seizures (e.g. glucose)
- Toxic seizures (e.g. drug withdrawal)
- Convulsive syncope
- Acute concussive convulsion
- Seizures within first week after brain trauma, infection or stroke
What is Electroencephalography (EGG) ?
An EEG is a test that detects abnormalities in your brain waves, or in the electrical activity of your brain
Explain the seizure type - Partial ?
- Simple – patient remains
conscious. Also known as ‘auras’ - Complex – patient has impaired consciousness
if the seizure spreads to the
reticular formation (in the brainstem) - Partial seizures are also known as focal seizures
Explain the seizure type - Generalised (tonic-clonic) ?
- Normal record
- Tonic (contractions; lose
consciousness) - Clonic (jerks)
- Coma
- Lasts 3-5 min
- Also known as grand mal seizures
Explain the seizure type - Generalised (absence) ?
- Occur in children
- Patient stops, stares
and is unaware; no
motor disturbance - Rhythmic discharge;
Spike-and-wave
- Also known as petit mal seizures
What are some other generalised seizures ?
Myotonic seizures and atonic (or drop) seizures
Types of wave on a normal EEG ?
- Delta waves (0.5–4 Hz). Sleep and in children < 1 year old.
- Theta waves (4–7 Hz). Sleep and in young children.
- Alpha waves (8–13 Hz): Awake relaxation w/eyes closed
- Beta waves (13–30 Hz). Conscious thought (frontal lobes)
- Gamma waves (30–100 Hz). Working memory and attention
What is the typical amplitude ?
About 25–100 mV
As neuronal ensembles become more synchronised, voltage changes in the
EEG become ?
Larger and prominent over normal EEG waves
What are sudden changes in activity referred to as ?
Paroxysmal activity
Briefly explain abnormal waves on an EEG ?
- Sharp waves: Last 80-200 milliseconds.
- Spikes: very large, fast waves. Last < 80 ms.
- Spike & wave: >1 brief spikes followed by a slow wave (3 Hz) - typical of absence seizures
- Polyspikes: burst of spikes
- Polyspike & waves
What does Ictal activity refer to ?
- Ictal refers to a sudden physiological attack (e.g. stroke, seizure, headache)
- In the context of epilepsy, ictal refers to the seizure event.
During the interictal period abnormal activity is confined to the seizure focus by?
Inhibitory surround, but this breaks down and/or is overcome at the onset of a focal seizure, leading to synchronisation
Explain seizure spread in a partial seizure ?
Spread locally via:
- Intrahemispheric fibres
- Corpus callosum
- Subcortical centers
Explain seizure spread in a generalised seizure ?
Spread locally via:
- Thalamus
