Seizures Flashcards
what is a seizure?
an episode of inappropriate electrical discharge resulting in disordered brain activity
what is epilepsy?
a condition in which there are repetitive but largely unpredictable episodes of seizure activity
what is glutamate?
an excitatory neurotransmitter found throughout the nervous system
what is GABA?
an inhibitory neurotransmitter found throughout the nervous system
explain the processes involved in the normal action potential of a neuron
what does ‘focal’ mean in terms of seizures?
a specific area of the brain
what does ‘generalized’ mean in terms of seizures?
affecting both hemispheres
what does the term ‘motor abnormalities’ refer to?
movement
what does ‘non-motor abnormalities’ refer to in regards to siezures?
sensory and cognition
explain the typical events that occur at a synapse during a seizure
innapropriate depolarisation > triggers calcium channels to open > influx of calcium at axon terminal > releases neurotransmitter contained in vessicle into the synapse > neurotransmitters in synapse bind to appropriate receptors on postsynaptic membrane > cause action potential in next neuron > process repeats in disorganised manner > causes disorganised brain function of some description
what is the normal resting membrane potential and threshold potential of a neuron?
resting membrane potential = -70
threshold potential = -60
how can a malfunctioning sodium-potassium (Na/K) pump lead to seizures activity?
The Na/K pump is essentially responsible for ‘cleaning up’ excess ions and returning a cell to its resting membrane potential (RMP). If it is malfuncitoning (hypoglycaemia/hypoxia/structural damage) it may not effectively balance the positive and negative ions. If this occurs and the RMP is more positive than it normally is, e.g. if it sits at -62 then only a small amount of stimulation will cause the cell to reach the thresholod potential and propogate an action potential.
what are the two things that are primarily going to imact the appropriate functioning of the Na/K pump?
oxygen and glucose
why does trauma lead to seizures?
trauma often leads to damage of cells and impacts the integrity of the cell membrane, meaning ions are able to pass across thr membrane innapropriately and cause action potentials to occur
why do toxins often lead to seizures?
toxins can impact the integrity of cell membranes, damage receptors, etc. Essentially impacts permeability of cell and makes it easier for ions to pass across the membrane innapropriately
how does midazolam work to treat seizures?
midaz acts on GABA receptor > receptor opens and allow negatively charged Cl ion to enter the cell > reduces the resting membrane potential of the cell (hyperpolerizes the cell) > makes it harder for the cell to be polarized
what is an aura?
essentially just a strange sensation that some people get before having a seizure. It can manifest in many ways e.g. a strange taste in the mouth, slightly disturbed vision, a smell, etc.
what does catatonic mean?
unconcious/dissociation - no stimuli coming in e.g. an absent seizure
what does ‘tonic’ mean?
muscle stiffness (motor NS) - often seen in a tonic clonic seizure
what does ‘clonic’ mean?
disordered jerky movements (motor NS) - e.g. in tonic clonic seizure
are you more likely to be unconcious in a focal or generalized seizure?
generalized
what does ‘tonic-clonic’ mean?
a relaxed muscle phase followed by a contract muscle cycle (motor NS)
what does ‘atonic’ mean?
flaccid muscles
what does ‘myoclonic’ mean?
isolated jerky movements (e.g. in one arm or leg, motor dysfunction)
