27 Anticonvulsants Flashcards
What is epilepsy?
a chronic neurologic disorder that is characterized by
recurrent (two or more) and unpredictable seizures generally arising from the abnormalities of cerebral cortex.
How is epilepsy characterized?
by type of seizure and EEG
T/F: The more severe seizures tend to have abnormal and excessive EEG discharges of synchronized activity of a group of neurons
F; all seizures have this quality, regardless of severity
When do most epileptic patients have their first seizure?
before age 18
How many patients are seizure free with antiepileptic medications?
90%
What is primary epilepsy?
no specific anatomic cause for seizure is evident; seizures may be due to an inherited abnormality, and patients are often treated with antiepileptics for life
What is secondary epilepsy?
epilepsy due to illness or injury; antepileptic drugs are taken until primary cause of seizures is resolved
which type of epilepsy is more common, primary or secondary?
primary (70%)
what is partial epilepsy?
epilepsy that originates in a small group of neurons that constitute a seizure focus; may spread throughout the entire cortex and become generalized tonic-clonic seizures
what is simple partial epilepsy?
partial epilepsy with no impairment of consciousness
what is partial complex epilepsy?
partial epilepsy with impairment of consciousness and a dreamy disaffective state, can spread
T/F: simple and complex partial seizures may spread throughout the cortex and progress to secondarily generalized seizures
F; only complex can
what are generalized seizures?
Seizures that spread throughout both hemispheres of brain and involve an immediate loss of consciousness
Are generalized seizures always convulsive?
sometimes, not always
What is the most common and most dramatic type of epilepsy?
Tonic-clonic (grand mal)–30% of seizures
describe the two phases of grand mal seizures
Tonic phase (<2-3 min): Rhythmic contraction of arms and legs
what is absence or petit mal epilepsy?
Brief, abrupt loss of consciousness; patient often unaware
of attacks
what is myoclonic epilepsy?
Short episodes of muscle contractions that may reoccur
for several minutes (single or multiple myoclonic jerks)
what typically causes myoclonic epilepsy?
permanent neurologic damage from hypoxia, uremia, encephalitis, or drug poisoning
What are febrile seizures?
Generalized tonic-clonic convulsions of short duration occuring in young children (3 months - 5 years of age) during illness accompanied by high fever
what is status epilepticus?
Repeated seizures without recovery between them;
consciousness is not regained between seizures
how long does status epilepticus last?
Seizures last at least 30 min
why is status epilepticus a medical emergency?
lack of oxygen can lead to systemic hypoxia, acidemia, hyperpyrexia, cardiovascular collapse and permanent brain damage
What tests are useful in the diagnosis of epilepsy?
EEG, SPECT imaging?
what does SPECT stand for?
Single-photon-emission-coherence tomography
what does SPECT measure?
regional blood flow in the brain
what are the two general methods by which antiepileptic drugs reduce seizures?
1) Alter ionic conductances (Na or Ca channels) to suppress firing of action potentials
2) enhance GABAergic transmission
what are the major drugs that alter ionic conductances to suppress firing of action potentials (list both Na and Ca channel blockers)?
Inhibit Na channels: carbamazepine, phenytoin, lamotrigine, and valproic acid
Ca channels: ethosuximide and valproic acid
what are the major drugs that enhance GABAergic neurotransmission
barbiturates (phenobarbital, primidone), benzodiazepines
(diazepam, lorazepam, clonazepam), and valproic acid
what does inhibition of voltage gated Na+ channels do to the action potential?
prolongs the refractory period and reduces sustained firing
what does inhibition of voltage gated Ca2+ channels do to the action potential?
inhibits rhythmic depolarizations
what are some non-pharmacologic treatments of epilepsy?
surgery and chronic vagal nerve stimulation
what is the drug of choice for initial therapy of epilepsy in adults?
phenytoin
what are some common side effects of antiepileptics?
drowsiness and sedation, ataxia, nausea and vomiting, skin rash, and metabolic changes
