seizure disorder Flashcards
siezure
paroxysmal (sudden) disorder of the CNS characterized by abnormal cerebral neuronal discharges with or without loss of consciousness
some synchrony to them
result of disordered, synchronous, excessivem and rhythmic firing of a population of brain neurons
convulsion
specific seizure type where the attack is manifested by involuntary muscle contractions
epilepsy
repeated seizures due to damage, irritation and/or chemical imbalance in the brain which leads to a sudden, excessive, synchronous electrical discharge
seizure originates in the ___
gray matter of ant cortical or subcortical area of the brain (thalamus)
focal or partial seizures
60% activity starts in 1 area of the brain only part of the brain is affected usually due to a lesion can evolve to generalized seizure simple VS complex simple- no loss of consciousness or altered awareness, sensory disturbances complex - altered awareness
generalized seizures
40%
no focal point
both hemispheres involved
typically involve a loss of consciousness
referred to as “primary” or “idiopathic”
most presumed to be genetic
absence, tonic clonic, myoclonic, clonic, tonic, atonic
simple partial seizure pathophysiology
25% of partial seizures
limited convulsions (jerking limited to 1 body part)
limited sensory disturbance
NO loss of consciousness
subjective experiences (auras): abdominal discomfort, sense of fear, altered taste, unpleasant smell, result of abnormal electrical activity
complex partial seizure pathophysiology
75% of partial seizures
clouding of consciousness, altered awareness
staring
automatisms (repetitive motor behaviors): clicking, chewing, lip smacking with no memory
disturbances of visceral, emotional and autonomic systems
followed by confusion, fatigue and throbbing headache (postictal state)
aura is common*
postictal state
after seizure (complex), pt will not recover a normal level of consciousness immediately
may last seconds to hours depending on: area of brain affected, length of seizure, use of AEDs, age
Sxs: confusion, disorientation, anterograde amnesia
absence seizures pathophysigology
generalized seizure
typical or atypical
typical (petit-mal): *brief loss of consciousness, staring or eye flickering, begin abruptly, repetitive, *no convulsions, aura, or postictal period
(no consciousness, no convulsions)
atypical: slower onset, more difficult to control pharmacologically than typical
non-absence generalized seizures
myoclonic: shock-like contraction of the muscles, isolated jerking of head, trunk, body
tonic: children, rigidit as a result of increased tone in extensor muscles
clonic: babies and young children, rapid, repetitive motor activity
atonic: loss of muscle tone, fall of standing (drop attacks)
tonic-clonic: tonic immediately followed by clonic phase, “grand-mal”, characteristic of epilepsy
status epilepticus: single prolonged seizure
tonic-clonic seizure pathophysiology
generalized, “grand mal”
most dramatic of all epileptic seizures
first phase: tonic; begins abruptly often with diaphragm contraction, rigidity in all extremities (15-30 seconds), tonus is interrupted by a tremor that corresponds to relaxation
second phase: clonic; begins as relaxation becomes more prolonged, involves violent jerking (hyperpolarization and depolarization back and forth) that lasts 1-2 minutes
jerking followed by stuperous state
tongue or cheek may be bitten
urinary incontinence is common
primary have no evidence of localized onset
secondary start as partial seizure, could be an aura
status epilepticus pathophysiology
repetitive seizure activity in which the patient does not regain consciousness between seizures OR a continuous, single seizure episode lasting over 30 minutes
aka: greater than 5 minutes of continuous seizure activity OR recurrent seizure activity without return to baseline
therapeutic goal is to bring seizures under control within 60 minutes to minimize neurologic and CV complications, including: abnormal glucose utilization, compromised CNS blood flow (O2), lactic acid accumulation, CV collapse (arrhythmia), long term impact on cognitive function and worsening of seizure disorder
excitatory NTs
AMPA, NMDA, Ca
inhibitory NTs
GABA, K
epilepsy statistics
1-2% of population, 1/5 will experience some seizure activity in their lifetime, 50-75% of pts w epilepsy are successfully treated with therapeutic agents
**drug therapy can be gradually withdrawn in pts who have been clinically-free of seizures for 2-5 years
triggers of SE
underlying conditions: prenatal injury, cerebrovascular Dx, brain tumors, head trauma, infection, hemorrhage, anoxia
general perturbations: metabolic disturbances (hyperventiliation, blood gas, pH, hypoglycemia), sleep deprivation, stress, alcohol withdrawl, *AED withdrawl (sudden discontinuation), repetitive light stimulation
drugs that aggravate or inc risk of seizure
alcohol, theophylline, CNS stimulants, bupropion, OCs, withdrawl from depressants, clozapine
4 MOAs of anticonvulsant drugs
- inhibition Na influx, prolong inactivation of Na channels
- inhibition of Ca influx (critical for absence seizures)
- stimulation of GABA-mediated neuronal inhibition
- inhibition of excitatory transmitters (glutamate)
phenytoin
***Strong P450 and UGT inducer; teratogen – pregnancy category D, therapeutic serum conc 10 – 20 mcg/mL (calculate free phenytoin with albumin); boxed warning – cardiovascular events; decreased bone mineral density, SJS/TEN, nystagmus, ataxia, double vision, hepatotoxicy, hirsutism, gingival hyperplasia, alteration of Vitamin D metabolism; osteoporosis; status epilepticus – fosphenytoin dosed in phenytoin equivalents preferred to reduce risk of arrhythmias, hypotension, purple glove syndrome
carbamazepine
**Partial/generalized seizures, P450 inducer (including auto‐inducing own metabolism), hyponatremia, aplastic anemia, SJS/TEN (HLA‐B1502 testing in patients of Asian descent), DRESS syndrome (HLA‐ A*3101 testing – Northern European descent (not required, suggested), therapeutic range *4 – 12 mcg/ml, electrolytes, CBC w/platelets, decreased efficacy of OCs, teratogen – category D (some generics available)
drugs that inhibit Na presynaptic Na channels
phenytoin, carbamazepine, lacosamide, lamotrigine, valproate
barbituates
used to treat partial seizures and generalized tonic-clonic
phenobarbital: drug of choice in infants up to 2 months of age (sedative)
MOA: binds to an allosteric regulatory site on the GABAa receptor, increases duration* of Cl- channel-opening events (and thus enhances GABA inhibitory signaling)
DI: induces liver cytochrome P450 enzymes
toxicity: sedation, physical dependence
benzodiazepines
used to treat partial seizures and generalized tonic-clonic
diazepam: especially useful for tonic-clonic status epilepticus; often administered as a rectal gel for acute control of seizure activity
MOA: binds to an allosteric regulatory site on the GABAa receptor, increases frequency* of Cl- channel-opening events (and thus enhances GABA inhibitory signaling
toxicity: sedation, physical dependence (tolreance), not for chronic treatment
clonazepam: useful for acute Tx of epilepsy and absence seizures*
drugs that inhibit post-synaptic GABAa receptors
phenobarbital, benzodiazepines
gabapentin MOA
increases GABA release
NMDA and AMPA receptors
used to treat partial seizures and generalized tonic-clonic
NMDA: glutamate binding triggers an influx of Na and *Ca and and efflux of K
AMPA: glutatamte binding triggers an influx of Na and and efflux of K
succinimides
used to treat absence seizures
MOA: blocks T-type Ca channels in thalamic neurons, T=type Ca channels are thought to be involved in generating the rhythmic cortical discharge of an absence attack
toxicity: GI distress, sedation
drugs that inhibit Ca channels in the presynaptic neuron
ethosuximide, lamotrigine, levetiracetam, valproate
levetiracetam MOA
MOA: binds the synaptic vesicular protein SV2A and thus interferes with synaptic vesicle release and neurotransmission, also appears to interfere with Ca entry through Ca channels and with intraneuronal calcium singaling
drugs that inhibit NMDA receptors
felbamate
drugs that inhibit AMPA receptors
topiramate
drugs that inhibit GABA transporter
tiagabine
drugs that inhibit GABA transaminase
vigabatrim
always counsel on the interaction between anticonvulsants and ___
oral contraceptives