Seizure disorders & Epilepsy Flashcards
What is a seizure?
Spontaneous uncontrolled abnormal brain activity
A transient abnormal event, which is caused by a paroxysmal (sudden) discharge of cerebral neurons
What does ‘ictus’ mean?
Can refer to any acute event but in the case of epilepsy it refers to the seizure
What does ‘aura’ mean?
Sensory disturbances that precede a seizure by a few minutes
Can be visual, tactile, olfactory, anything
What is epilepsy?
A tendency to spontaneous, intermittent, abnormal, electrical activity in part of the brain manifesting as seizures
What is the differential diagnosis of a seizure?
Epilepsy Non-epileptic seizure Postural syncope Migraine Cataplexy Dystonia T.I.A
What is cataplexy?
A sudden and transient episode of muscle weakness accompanied by full conscious awareness
Typically triggered by emotions such as laughing, crying, or terror
What is dystonia?
Sustained muscle contractions cause twisting and repetitive movements or abnormal postures.
The movements may resemble a tremor.
What causes a blackout?
Problem with blood circulation
- heart problem
- low BP
Disturbance of brain function
- epilepsy etc.
When does epilepsy usually present?
In childhood or adolescence
What causes epilepsy?
Genetics
Developmental abnormalities
After effects of trauma / surgery
Hypoxia
Drugs
CNS infection
What is the pathogenesis of an epileptic seizure?
Each person has a ‘seizure threshold’: the level of excitability at which the neuron cells will depolarise uncontrollably
In epilepsy this seizure threshold is lowered
When the threshold is reached you get
Abnormal synchronised depolarisation of neural cells and thus neurons
Normal inhibitory mechanisms fail
This causes symptoms that depend on where the action is
Which neurotransmitters are involved in epilepsy?
Glutamate: excitatory
GABA: inhibitory, this fails to inhibit activity
What is meant by a ‘seizure threshold’?
The level of excitability at which neural cells will discharge uncontrollably
This levels is lowered in epilepsy
What are some triggers that push an area of the brain past it’s seizure threshold?
Flashing lights Alcohol Sleep deprivation Physical / mental exhaustion Infection
How are epileptic seizures classified?
Partial: focal, remain confined to one part of the brain
Generalised: originate from midbrain or brainstem and spread to both hemispheres of the brain
What is a secondary generalised seizures?
Partial seizures which spread to lower areas of the brain, which results in the initiation of a generalised seizure
What types of partial seizures are there?
Simple: without impaired awareness
Complex: with impaired consciousness
What are the usual features of a partial seizures?
Remains conscious
Depends on the area of the brain affected
In temporal lobe:
- olfactory and visual
- hallucinations
- blank staring
- jamais vu or deja vu
In motor cortex:
- called Jacksonian seizures
- movement that starts in one area and spreads
- may be jerking or simply holding a certain position
In occipital lobe:
- visual phenomena
Todd’s paralysis post seizure
What is Todd’s paralysis?
Sometimes occurs after a simple partial seizure
Paralysis of the involved limbs for a while after
What is jamais vu?
Feelings of unfamiliarity or unreality
How can you distinguish a simple partial seizure from a complex partial seizure?
Simple: they will have full awareness and remain conscious
Complex: impaired consciousness and memory
Automatism
What is automatism?
When a person has impaired consciousness, but their motor function is still intact so they can move about
What types of generalised seizures are there?
Absence seizures: petit mal
Tonic clonic seizures: grand mal
What are the usual features of an absence seizure?
Childhood onset
Patient unresponsive to stimuli but still conscious
They stare blankly, may go pale
Usually only last a few seconds
