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.
petit mal: genetic component?
in some families there is a mutated GABA or glutamate receptor
generalized epilepsy with non-convulsive seizures (atonic seizure): what are the characteristics?
atonic seizures: loss of muscle tone, head-drops or falls
EEG shows diffuse flattening, reflecting cortical inhibition
often seen in context of diffuse brain damage. poor prognosis.
how is a petit mal seizure different from an atonic generalized seizure?
petit mal is more absence, staring, no movement but no loss of tone
atonic generalized is characterized by a drop or fall due to loss of tone.
what distingishes a complex partial seizure from a simple partial seizure?
complex = consciousness is affected. simple = consciousness not affected.
partial v focal: terminology?
they are the same thing
what does a partial seizure look like?
blank stare, focal muscle jerks, simple automatisms, reactive automatisms
partial seizure: aura?
may have aura if it does not spread too quickly
how can a hemorrhage cause a seizure?
acute trauma –> hemorrhage -> degradation product of hemoglobin = hemosiderin and it is a brain irritant/ epileptogenic.
how is mesial temporal sclerosis associated with epipelsy?
common cause. may be due to trauma, infection, malformation, or febrile convulsion
temporal lobe epilepsy on EEG?
focal sharp activity on bottom leads associated with temporal lobe.
Clinical approach to epilepsy: what to consider about the history?
family history, trauma, meningitis?
frequency? more than one type?
aura? may give clue to location if focal
Clinical approach to epilepsy: what to consider about the physical exam?
often the neuro exam is normal
look for neuro-cutaneous disorders
occasional hemi-pareisis or hemi-atrophy
how does an epileptic aura compare to a migraine aura?
much shorter: seconds to minutes
what is Todd’s paralysis?
focal weakness in a part of the body after a seizure
Clinical approach to epilepsy: what to consider if evaluating in ER?
Get a CT scan. (tumor, stroke, hemorrhage)
check CBC, chemistry, liver profiles (infections, ionic imbalance)
EKG and chest xray
spinal tap (infections)
elective EEG (focal v partial)
what is status epilepticus?
emergency, continuous or recurrent seizures over 30 min without waking up in between.
what might cause status epilepticus?
sedative withdrawal, discontinuation of anticonvulsants
what an result from status epilepticus?
resp failure, lactic acidosis, aspiration, changes in BP, hyperthermia
acute treatment of a seizure?
- IV lorazepam. lasts longer than diazepam. short half-life
- longer term therapy: IV phentoni or fosphenytoin
- status epilepticus: IV phenobarbital. intubation.
chronic treatment of seizures?
- first seizures usually untreated. only 50% recur
- provoked seizures are treated acutely but not long-term
- recurrent seiz are treated chronically. may withdraw meds eventually in 50% of pts
what meds are best for child-bearing women?
lamotrigine and levetiracetam
which is easier to control: generalized or focal epilepsy?
generalized.
overall, what is the most effective drug for generalized?
valproate
which is more common: generalized or focal epil?
focal.
overall, what is the most effective drug for focal?
carbamazepine. can also use lamotrigine and levetiracetam
what is the patient response to drugs for focal epil?
50% do well on first drug, 20% do well on next drug
what is a treatment if drugs have failed?
vagus nerve stimulation. like a pacemaker. intermittent/regular stimulation
when drugs, vagus nerve stimulation, cerebral stim fail?
open the head and remove some brain.
for what type of epilepsy is surgical treatment particularly effective?
mesial temporal sclerosis. often refractory to meds, lesion removal is effective
