epilepsy 1 Flashcards
define epilepsy
a neurological condition affecting the brain
a seizure disorder
a chronic condiction characterised by a tendency to have recurrent, unproviked seizures
a neurological condition characterised by recurrent epleptic seizures unprovoked by any immediately identifiable cause
what is a seizure?
‘a paroxysmal alteration of neurological function caused by the
excessive, hypersynchronous discharge of neurons in the brain’
‘a temporary alteration in brain function due to excessive and/or
hyper-synchronous neuronal activity’
‘a sudden surge of electrical activity in the brain that usually
affects how a person feels or acts for a short time’
‘a transient and involuntary change in behaviour or neurological
status caused by abnormal, excessive or synchronous neuronal
activity in the brain’
what is an epileptic seizure?
a clinical phenomenon resulting from ‘an occasional,
sudden and excessive discharge of gray matter’
spontaneous & unprovoked
what is epilepsy?
a cluster of clinical syndromes characterised by a
predisposition to (or a tendency to have) recurrent,
spontaneous & unprovoked seizures
a symptom of abnormal brain function
cellular & molecular alterations in the cerebral cortex
what are the co-morbidities associated with epilepsy?
associated with 2-fold prevalence of major
depression, anxiety disorders & suicidal ideation
increased prevalence of cognitive dysfunction,
migraine & trauma
what are the social and economic limitations associated with epilepsy?
stigma social exclusion & discrimination
driving & employment restrictions
how does epilepsy influence mortality?
associated with 2-3 fold increased risk of premature
death
symptomatic epilepsy associated with up to 18 years
reduction in life expectancy
increased incidence of suicide
SUDEP as most important mode of death
what causes an epleptic seizure?
reflects abnormal hyper-synchronous electrical
activity of neuronal networks
too many brain cells become excited at same time
generation of an ‘electrical storm’ in the brain
what is epileptogenesis?
the process by which normal brain tissue is
functionally transformed into tissue capable of
generating recurrent, spontaneous seizures
what causes epilepsy?
epilepsy involves conversion of a normal neuronal
network into a hyperexcitable network
results from
an imbalance in inhibitory & excitatory
neurotransmission –i.e. disruption of normal balance
between excitation & inhibition in the brain
an abnormality in neural connectivity –i.e. a greater
spread & abnormal neuronal recruitment by oscillatory
networks
or combination of both factors
how does the balance between excitation and inhibition in the brain get disrupted?
Excitation (too much)
Ionic –inward Na+ and/or Ca++ currents
Neurotransmitter –glutamate and/or aspartate
Inhibition (too little)
Ionic –inward CI- and/or outward K+ currents
Neurotransmitter –GABA
what causes control and what causes a seizure in the brain?
control= IPSPs, k+ efflux, cl- influx, pumps, low ph seizure= EPSPs , na////= influx, ca++ currents, paroxysmal depolarisation
what causes abnormality in neural connectivity?
a greater spread & abnormal neuronal recruitment by oscillatory networks increased synchronization of neuronal firing Due to: enhanced excitatory transmission failure of inhibitory mechanisms enhanced inter-neuronal connectivity changes in intrinsic neuronal properties
what are the classes of epilepsy?
Clinical cases with no obvious identifiable cause
idiopathic or ‘primary’ epilepsy
presumed genetic in origin (genetic predisposition)
Clinical cases with obvious identifiable cause
symptomatic or ‘secondary’ epilepsy
what would be an example of an obvious identifible cause?
head injuries or birth traumas congenital abnormalities brain tumours stroke neurodegenerative disease infections –meningitis, encephalitis, etc
