Epilepsy

Question 1

What is epilepsy?

Answer 1

A chronic disorder characterized by recurrent seizures

Question 2

What is a seizure?

Answer 2

A short term episode of abnormal firing of cerebral neurons

Partial or generalized

Question 3

What can cause seizures?

Answer 3

Fever, head injury, tumor, hereditary, alcohol withdrawal and metabolic disorder

Question 4

What is a partial (focal) seizure?

Answer 4

Initiated in neurons in a localized area of one cerebral hemisphere
Simple, complex, secondary generalization

Question 5

What is a simple partial seizure?

Answer 5

No loss of conciousness

Preceeded by an aura sometimes

Question 6

What is complex partial seizure?

Answer 6

Impaired consciousness often with automatisms

Question 7

What is a secondary generalized partial seizure?

Answer 7

Seizures that spread to activate both hemispheres

Part of body begins to tingle then jerk, then jerking spreads throughout body

Question 8

What is a generalized seizure?

Answer 8

Simultaneous activation of both cerebral hemispheres

Tonic-clonic, absence

Question 9

What is a tonic-clonic generalized seizure?

Answer 9

Loss of consciousness, extension then jerking of the body with stiffness finishing by passing out into a deep sleep

Question 10

What is an absence generalized seizure?

Answer 10

Impaired consciousness sometimes with automatisms

Blanking out for a few seconds, blinking

Question 11

What does a normal EEG look like?

Answer 11

Activity mostly in the left and right occipital lobes

Question 12

What does the EEG of a partial seizure look like?

Answer 12

More activity in one side of the brain (left frontal and temporal)

Question 13

What does the EEG of a complex partial seizure look like?

Answer 13

Similar to that of a simple partial seizure

Question 14

What does the EEG of a generalized tonic-clonic seizure look like?

Answer 14

All parts of the brain show large spikes (close together then more spread apart throughout) in activity.

Question 15

What does the EEG of a generalized absence seizure look like?

Answer 15

Very similar large, organized spikes throughout entire brain

Question 16

What are the 4 mechanisms of action of anti-epileptic drugs?

Answer 16

Block voltage-dependent sodium channels (decreases neuronal firing)
Inhibit excitatory (glutamate) transmission
Increase inhibitory (GABA) transmission
Block voltage-activated Ca channels (stops depolarization)

Question 17

How does depolarization and hyperpolarization affect a Na cell?

Answer 17

Depolarization enhances channel opening (Gate A)
Hyperpolarization blocks channel opening
Channel then becomes inactive (Gate B closes)

Question 18

Where do many anti-epileptic drugs work on the Na channel?

Answer 18

Prevent the conversion of the inactive channel to closed channel (From closed gate B to gate A)

Question 19

What drugs are used to treat partial seizures?

Answer 19

Carbamazepine, phenytoin or valproate

Question 20

What drugs are used to treat generalized tonic-clonic seizures?

Answer 20

Carbamazepine, phenytoin or valproate

Question 21

What drugs are used to treat generalized absence seizures?

Answer 21

Ethosuximide

Question 22

What drugs are used to treat generalized tonic-clonic and absence seizures?

Answer 22

Valproate

Question 23

What drugs are used to treat atypical generalized seizures?

Answer 23

Valproate

Question 24

What can be added to drug therapy of partial seizures?

Answer 24

Lamotrigine, gabapentin or topiramate

Question 25

How does carbamazepine work?

Answer 25

Inhibits voltage-gated sodium channels and induces it's own metabolism Dose adjustments are required

Question 26

What are the drug interactions with carbamazepine?

Answer 26

Can enhance the metabolism of many other antiepileptics including phenytoin and valproate toxicity

Question 27

What are the adverse effects of carbamzepine?

Answer 27

Double vision, ataxia (poor balance, uncoordination), nausea High doses: drowsiness Skin rash and leukopenia (low white blood cells)

Question 28

How does phenytoin work?

Answer 28

Blocks voltage-gated sodium channels Absorption differs among formulations Dramatic increases in plasma levels with small increases in dose

Question 29

What are the drug interactions with phenytoin?

Answer 29

Highly bound to plasma proteins | Induces CYP 3A4 and thus the metabolism of carbamazepine, valproate, vitamin K and contraceptives

Question 30

What is the metabolism of phenytoin enhanced by?

Answer 30

Phenobarbital and carbamazepine, requires dose adjustment

Question 31

What are the adverse effects of phenytoin?

Answer 31

Double vision, ataxia, gingival hyperplasia, hirsutism (hair growth), mild peripheral neuropathy, megaloblastic anemia, osteomalacia

Question 32

How does phenobarbital and primidone work?

Answer 32

Enhance the inhibitory effects of GABA Primidone is metabolized to phenobarbital Induces it's own metabolism

Question 33

What are the drug interactions with phenobarbital and primidone?

Answer 33

Induces liver microsomal enzymes so drug interactions are common with vitamin K and oral contraceptives

Question 34

What are the adverse effects of phenobarbital and primidone?

Answer 34

Drowsiness, ataxia, respiratory depression and decreased motor skills Skin rash, dependence

Question 35

How does gabapentin work?

Answer 35

Increases the release of GABA and decrease the metabolism of GABA Not metabolized, doesn't induce hepatic enzymes Adjunctive therapy

Question 36

What are the adverse effects of gabapentin?

Answer 36

Sedation, dizziness, headache, tremor, ataxia, nausea, constipation Will resolve in 2 weeks

Question 37

How does topiramate work?

Answer 37

Inhibits voltage gated Na channels, increases GABA, inhibits glutamate Adjunctive therapy or mono in partial and tonic-clonic

Question 38

What are the adverse effects of topiramate?

Answer 38

Fatigue, dizziness, mental slowing and nausea

Question 39

How does lamotrigine work?

Answer 39

Blocks voltage gated sodium channels | Adjunctive therapy or mono for partial and absence

Question 40

What are the adverse effects of lamotrigine?

Answer 40

Dizziness, headache, skin rashes

Question 41

How does ethosuximide work?

Answer 41

Blocks voltage activated calcium channels

Question 42

What are the adverse effects of ethosuximide?

Answer 42

Stomach aches and vomiting (tolerance will develop) | Rash, may increase tonic-clonic seizures

Question 43

How does clonazepam work?

Answer 43

Enhances the inhibitory effects of GABA

Question 44

What are the adverse effects of clonazepam?

Answer 44

Sedation and tolerance to anti-seizure effects

Question 45

How does valproate work?

Answer 45

Voltage gated sodium and calcium channels, enhances inhibitory effects of GABA

Question 46

What are the drug interactions with valproate?

Answer 46

Inhibits metabolism of other drugs including antiepileptics

Question 47

What are the adverse effects of valproate?

Answer 47

Nausea, vomiting (initiate therapy slowly) Tremor at high concentrations Spina bifida in babies if taken while pregnant

Question 48

What are the other uses of anti-epileptic drugs?

Answer 48

Bipolar disorder (carbamazepine, valproate), anxiety disorders, alcohol abuse, spasticity, migraine, cluster headache, neuropathic pain (gabapentin)

Question 49

What drugs are used in the case of status epilepticus?

Answer 49

IV diazepam or lorazepam are used to stop the seizures and phenytoin may be initiated for longer term control have to gradually increase antiepilieptics

Question 50

What must be monitored while on antiepileptics?

Answer 50

Blood level monitoring to maintain therapeutic levels, especially for drugs that can affect drug metabolizing enzymes

Question 51

What should be done about seizures in pregnancy?

Answer 51

Uncontrolled seizures are a greater risk to the fetus than the drugs Lowest effect dose should be used, one drug at a time (dose may need to be increased due to increased metabolism-monitor blood levels at least once a month)