Epilepsy Flashcards
Epilepsy defintion
Causes
is a tendency to?
Abnormal, excessive electrical discharge from neurones. Imbalance between excitation and inhibition.
Often associated with a loss of consciousness
Causes include genetic, structural or metabolic/functional
have recurrent seizures
What causes seizures?
note alterations of ion channels
Occur as a result of abnormal synchronous activation of many hyperexcitable neurons.
Can spread through synaptic and non synaptic pathways
What are the classifications of epileptic seizures?
Note a seizure can start focally and end generalised
Focal: Manifestations depend on which part of the brain is affected. Conscioiusness is preserved in simple ones.
Generalised: manifestations vary greatly, loss of responsiveness: With or without motor manifestations
Tonic, clonic and myoclonic seizures. Occur usually with what seizure type?
Tonic: sustained contraction of axial and limb muscles
Clonic: Regular repeated tonic contractions
Myoclonic: sudden brief jerks
Generalised.
What can be said about loss of consciousness?
Not always a product of a epileptic seizure. May also be a result from other pathological processes.
What are the types of glutamate transmitters? EXCITATORY
NMDA and non NMDA receptors
NMDA vs non NMDA recpetors
NMDA: Slow to activate, selective for calcium. Magnesium blocks channel when fully polarised, and is expelled when partially depolarised, to continue depol.
non NMDA: Rapidly inactivate and activate, allow cations through, not really calcium
GABA receptor INHIBITORY
Receptor binds two GABA, will open and allow CL- in to hyperpolarise cell.
Benzodiazepines and barbiturates can bind to these
Mutations in ion channels
K+: In children can have seizures. Not always lasting
Na+: bad in type 1 channel mutations e.g Dravets Syndrome,
Absence seizure
generalised?
Brief loss and gain of consciousness can be clonic, atonic etc
What drugs will induce seizures? (3 types)
Block GABA: penicillin
Glu activators: low Mg2+, kainate, domoic acid
Block K+ voltage 4-aminopyridine (MS?)
Drugs to treat seizures types and examples
Na+ channel blockers: carbamazepine and phenytoin. Prevent sustained repetitive firing
Enhancement of GABA transmission: diazepans and barbiturates. vigabatrin
Calcium channels:
Glutamate block:
Autoantibody induced epilepsy
Anti potassium channels - epilepsy and encephalitis
Anti NMDA channels
What is the kindling effect of seizures?
The fact that one seizure means that subsequent seizures are more likely. Unsure in humans
Effects of seizures
Rearrangement of local neuronal circuits and loss of neurons. e.g temporal lobe epilepsy causing memory loss
