10. Epilepsy Flashcards
define epilepsy
tendency to have seizures in absence of provocations that would cause the normal brain to have a seizure. due to electrically irritable brain
besides epilepsy, what else can cause seizures?
acute brain injury, tramua, anoxia, fever.
what causes a seizure at the neuronal level?
excitation that substantially exceeds inhibition
what is the action of glutamate?
binds to receptors that open Na and Ca channels depol cell, make neuronal firing and seizures more likely
in regards to glutamate, what is the action of some anti-epileptic drugs?
block release of glutamate (lamotrigine), or are glut receptor antagonists (topiramate)
what is the action of GABA?
inhibitory. opens a chloride channel that hyperpolarizes the cell. makes neuronal firing less likely.
in regards to GABA, what is the action of some anti-epileptic drugs?
imitate GABA/ agonists at GABA receptors (benzodiazepines, barbituates)
a specific gene that causes epilepsy?
mutation in gene 19 –> mutation in VG sodium channel. leaves your neurons excitable. causes generalized epilepsy with febrile seizures
what are generalized epilepsies associated with in terms of brain activity and presentations?
diffuse electrographic changes in the whole brain. may be tonic-clonic (grand mal), staring (absence/petit mal), tonic (stiffening), atonic (loss of muscle tone), myoclonic.
what are focal epilepsies associated with in terms of brain activity and presentations?
starts at one area, spreads to some extent. may start due to focal structural lesions, focal electrical abnormalities. may have confusion, aura, tonic-clonic.
what is a secondarily generalized seizure?
starts focal, spreads to become generalized.
define a primary generalized seizure?
- seiz activity visible in all areas of cortex simultaneously
- no warning/aura
- may be genetic or due to metabolic upset
- some primary epilepsies of childhood may be outgrown
primary generalized seizure due to metabolic upset: what are some of the upsets that can cause seizures?
electrolyte disturbance, organ failure, hypoglycemia, hypoxia, withdrawal from alc or drugs
epilepsy with generalized convulsive seizures but no other brain problems: what is the prognosis?
good prognosis. may be idiopathic or genetic. usually begins in childhood or adolescence
general tonic-clonic seizures (grand mal): what does it look like?
bilateral tonic extension followed by clonic activity. autonomic upset (pupils large, hyperthermia, tachy, salivation, bladder emptying)
what is clonic activity?
alternating jerks of activity of flexors and extensors, grunting respirations
general tonic-clonic seizures (grand mal): what will terminate the activity?
inhibitory transmitters that result in postictal period
what is a petit mal seizure?
type of generalized seizure. brief, no movement (except maybe eye blink or lip movement), no loss of tone, no memory, no postictal period.
petit mal: onset? prognosis?
begins with staring spells around school age. good prognosis, may outgrow. some develop convulsive seizures
what is juvenile myoclonic epilepsy?
type of generalized seizure. brief, prominent motor cortex involvement. may result in myoclonic jerks. may be due to mutated GABA receptor
what is a myoclonic seizure?
brief, generalized seizure often resulting in myoclonic jerks
what is tonic activity?
stiffening due to rapid repetitive neuronal firing
petit mal: appearance on EEG?
diffuse abnormalities, characteristic = 3 waves/sec.
petit mal: what neurons are involved?
diffuse involvement but not all neurons are involved. if every neuron were involved, pt would convulse. instead, this is like hitting the gas pedal while in neutral.
