27 Anticonvulsants

Question 1

What is epilepsy?

Answer 1

a chronic neurologic disorder that is characterized by

recurrent (two or more) and unpredictable seizures generally arising from the abnormalities of cerebral cortex.

Question 2

How is epilepsy characterized?

Answer 2

by type of seizure and EEG

Question 3

T/F: The more severe seizures tend to have abnormal and excessive EEG discharges of synchronized activity of a group of neurons

Answer 3

F; all seizures have this quality, regardless of severity

Question 4

When do most epileptic patients have their first seizure?

Answer 4

before age 18

Question 5

How many patients are seizure free with antiepileptic medications?

Answer 5

90%

Question 6

What is primary epilepsy?

Answer 6

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

Question 7

What is secondary epilepsy?

Answer 7

epilepsy due to illness or injury; antepileptic drugs are taken until primary cause of seizures is resolved

Question 8

which type of epilepsy is more common, primary or secondary?

Answer 8

primary (70%)

Question 9

what is partial epilepsy?

Answer 9

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

Question 10

what is simple partial epilepsy?

Answer 10

partial epilepsy with no impairment of consciousness

Question 11

what is partial complex epilepsy?

Answer 11

partial epilepsy with impairment of consciousness and a dreamy disaffective state, can spread

Question 12

T/F: simple and complex partial seizures may spread throughout the cortex and progress to secondarily generalized seizures

Answer 12

F; only complex can

Question 13

what are generalized seizures?

Answer 13

Seizures that spread throughout both hemispheres of brain and involve an immediate loss of consciousness

Question 14

Are generalized seizures always convulsive?

Answer 14

sometimes, not always

Question 15

What is the most common and most dramatic type of epilepsy?

Answer 15

Tonic-clonic (grand mal)–30% of seizures

Question 16

describe the two phases of grand mal seizures

Answer 16

Tonic phase (<2-3 min): Rhythmic contraction of arms
and legs

Question 17

what is absence or petit mal epilepsy?

Answer 17

Brief, abrupt loss of consciousness; patient often unaware

of attacks

Question 18

what is myoclonic epilepsy?

Answer 18

Short episodes of muscle contractions that may reoccur

for several minutes (single or multiple myoclonic jerks)

Question 19

what typically causes myoclonic epilepsy?

Answer 19

permanent neurologic damage from hypoxia, uremia, encephalitis, or drug poisoning

Question 20

What are febrile seizures?

Answer 20

Generalized tonic-clonic convulsions of short duration occuring in young children (3 months - 5 years of age) during illness accompanied by high fever

Question 21

what is status epilepticus?

Answer 21

Repeated seizures without recovery between them;

consciousness is not regained between seizures

Question 22

how long does status epilepticus last?

Answer 22

Seizures last at least 30 min

Question 23

why is status epilepticus a medical emergency?

Answer 23

lack of oxygen can lead to systemic hypoxia, acidemia, hyperpyrexia, cardiovascular collapse and permanent brain damage

Question 24

What tests are useful in the diagnosis of epilepsy?

Answer 24

EEG, SPECT imaging?

Question 25

what does SPECT stand for?

Answer 25

Single-photon-emission-coherence tomography

Question 26

what does SPECT measure?

Answer 26

regional blood flow in the brain

Question 27

what are the two general methods by which antiepileptic drugs reduce seizures?

Answer 27

1) Alter ionic conductances (Na or Ca channels) to suppress firing of action potentials
2) enhance GABAergic transmission

Question 28

what are the major drugs that alter ionic conductances to suppress firing of action potentials (list both Na and Ca channel blockers)?

Answer 28

Inhibit Na channels: carbamazepine, phenytoin, lamotrigine, and valproic acid
Ca channels: ethosuximide and valproic acid

Question 29

what are the major drugs that enhance GABAergic neurotransmission

Answer 29

barbiturates (phenobarbital, primidone), benzodiazepines

(diazepam, lorazepam, clonazepam), and valproic acid

Question 30

what does inhibition of voltage gated Na+ channels do to the action potential?

Answer 30

prolongs the refractory period and reduces sustained firing

Question 31

what does inhibition of voltage gated Ca2+ channels do to the action potential?

Answer 31

inhibits rhythmic depolarizations

Question 32

what are some non-pharmacologic treatments of epilepsy?

Answer 32

surgery and chronic vagal nerve stimulation

Question 33

what is the drug of choice for initial therapy of epilepsy in adults?

Answer 33

phenytoin

Question 34

what are some common side effects of antiepileptics?

Answer 34

drowsiness and sedation, ataxia, nausea and vomiting, skin rash, and metabolic changes