Epilepsy Flashcards
What is the definition of epilepsy?
- CHRONIC neurological disorder affecting the brain
- symptoms are RECURRENT seizures
- idiopathic
- must have 2 or more seizures of unknown etiology to be diagnosed with epilepsy
What is the definition of a seizure?
- temporary neurological reaction to sudden excessive electrical excitation of cortical neurons
- ## loss of awareness/consciousness, movement or sensation disturbances, changed mood or mental function
How can epilepsy be diagnosed?
- Brain imaging (EEG, CT, MRI, PET)
- Blood tests (secondary causes)
- Lumbar puncture (seizures could be caused by infection/bleeding of the brain)
What does an electroencephalography (EEG) tell you?
- non-invasive electrical record of the brain’s surface
- locates area of irregularly firing cortical neurons
- determines severity and type of seizure disorder (doesn’t actually diagnose epilepsy)
What does a CT scan tell you?
- looks for large abnormalities
- tumors/bleeds
- these could be causing the seizures
What does a MRI tell you?
- takes small picture slices of the brain
- next step after CT scan
- looks for tiny abnormalities in the brain
- small tumors, small bleeds, small clots
What is the purpose of a PET scan?
- it is a “behavioural” scan
- shows brain activity during specific actions
- if other parts of the brain “light up” during easy activities, there is something wrong
What is the effect of GABA?
- It opens up channels and allows more Cl- ions to flow into the cell
- This makes APs less likely to happen
Describe the initiation of a seizure
- bursts of APs from cortical neurons
- synchronization of these neurons (AP chain)
- prolonged depol –> repetitive AP
- hyper-excitability due to imbalance of neuronal membrane
What are the 2 excitatory transmitters utilized for seizure medications?
What do they do?
- aspartate attaches to AMPA receptor–> Na+ influx
- glutamate attaches to NMDA receptor –> Ca2+ influx
- influx of Ca2+ and Na+ causes an AP
Describe the ion situation in the imbalanced neuron
Na+ = excessive influx Ca2+ = excessive influx Cl- = insufficient influx K+ = insufficient efflux
Describe the propagation of seizure
- enough excitability to recruit surrounding cortical neurons
- lose surrounding inhibition
- spread of seizure to areas via cortical connections
Describe the termination of seizures
- ends after few seconds or mins
- spontaneous
- unknown mechanism
What happens if a seizure doesn’t terminate?
- it is known as status epilepticus
- brain cells begin to die
- fatal
- can be convulsive or non-convulsive
What are the 2 types of seizures?
What are their definitions?
Partial - originates in localized area of the brain
Generalized - occurs in both hemispheres of the brain
What are the different types of partial seizures?
- simple
- complex
- secondary generalized
What are the different types of generalized seizures?
- absence
- atonic
- myoclonic
- tonic-clonic
Describe a simple partial seizure
before: aura = physiological warning (scents, anxiety, deja vu)
during: symptoms depending on brain area Motor - twitching, stiffening Sensory - tingling Autonomic - abdominal discomfort Psychic - hallucinations, fear, sad person remains conscious/aware
After: memory intact, can recall what happened
Describe a complex partial seizure
Before: aura
During:
- impaired consciousness
- automatisms (mumbling, wandering, picking at clothes)
- may progress into generalized seizure
After:
- cannot recall event
- confusion and fatigue following
Describe absence generalized seizures
Before: no aura
During:
- brief lapse of consciousness, blank stare, unaware, then continue with activity
- begins and ends suddenly
- may occur many times during the day
After:
- continue with activity
- prompt recovery
Describe atonic generalized seizures
Before: no warning
During:
- abruptly lose muscle tone
- brief loss of consciousness
- collapse and fall
After:
- recover after a few seconds
- regain consciousness
Describe myoclonic generalized seizures
Before: no warning
During:
- muscle jerks/spasms
- may have 1 seizure or many in a row
- conscious throughout
After: memory intact
Describe clonic-tonic generalized seizures
Before: no warning
During:
- epileptic cry, loss of consciousness, collapse
- body stiffens (tonic)
- body jerks (clonic)
- convulsive
- change in breathing, bites tongue, incontinence
After:
- no recollection
- confused, tired, fatigued
What are the triggers of secondary seizures?
- head trauma
- head injury
- stress
- lack of sleep
- drug use
- alcohol withdrawal
- poor nutrition
- infection or disease
