Lecture 8: Epilepsy

Question 1

What is epilepsy?

Answer 1

A chronic disease characterized by recurrent seizures

Question 2

What is a seizure?

Answer 2

A sudden, brief disruption of the normal functioning of neurons in the brain

Question 3

Causes of epilepsy

Answer 3

Stroke

Brain tumor

Brain infection

Past head injury

Metabolic problems

Other neurological conditions

Genetic factors

Question 4

Causes of seizures

Answer 4

High fever, especially in infants

Drug use, alcohol withdrawal

Near-drowning or lack of oxygen from another cause

Metabolic disturbances

Head trauma

Brain tumor, infection, stroke

Complication of diabetes or pregnancy

Question 5

Classification of seizures

Answer 5

Partial (focal): initiated in neurons in a localized area of one cerebral hemisphere (include simple, complex and secondary generalization)

Generalized: simultaneous activation of both cerebral hemispheres (include tonic-clonic and absence)

Unclassified seizures

Question 6

Partial seizure subclassifications

Answer 6

Simple - no loss of consciousness

Complex - impaired consciousness often with automatisms

Secondary generalization - seizures spread to activate both hemispheres

Question 7

Generalized seizures subclassifications

Answer 7

Tonic-clonic - loss of consciousness, extension then jerking of body

Absence - impaired consciousness sometimes with automatisms

Question 8

Motor homunculus in seizures

Answer 8

Seizures are sometimes associated with motor activity or sensations, which can give insight as to the brain location of the seizure focus

Question 9

Simple partial seizure characteristics

Answer 9

Pressure in stomach, rises to chest

Smells odor

Nervous

Aura

Question 10

What is the EEG?

Answer 10

Electroencephalogram (EEG)

record of electrical activity of
brain by placing the electrodes on the scalp.

Question 11

EEG partial seizure

Answer 11

Abnormal activity in specific brain regions

See figure

Question 12

Complex partial seizure characteristics

Answer 12

Funny face

Surprised and distressed

picking things off shirt

Question 13

Partial Seizure with Secondary Generalization Characteristics

Answer 13

Tingling in an extremity that turns into jerking and spreads

Question 14

Generalized tonic clonic seizure characteristics

Answer 14

Shrieks

Muscles activated

Teeth clench

Question 15

EEG in tonic clonic seizures

Answer 15

abnormal electrical activity in all brain regions

Question 16

Generalized absence seizure characteristics

Answer 16

Typically in children

Absence of aura

Loss of consciousness

Question 17

EEG of generalized absence seizures

Answer 17

Slow wave electrical activity in all brain regions

Question 18

What is an anti-epileptic drug?

Answer 18

adrugwhichdecreases the frequency and/or severity of seizures in people with epilepsy

Treats the symptom of seizures, not the underlying epileptic condition

Does not prevent the development of epilepsy in individuals who have acquired a risk for seizures (e.g., after head trauma, stroke, tumor)

Question 19

What is the goal of AEDs?

Answer 19

to maximize quality of life by eliminating seizures (or diminish seizure frequency) while minimizing adverse drug effects

Question 20

Mechanisms of drug action

Answer 20

1. Use dependent blockade of voltage-dependent sodium channels - Reduce the rate of sodium channel opening
2. Inhibit excitiatory (Glutamate) neurotransmission - Decrease glutamate exposure and reduce neuronal firing
3. Increase inhibitory (GABA) neurotransmission - Enhance chloride influx, hyperpolarize neurons and reduce neuronal firing
4. Block voltage - activated calcium channels - Neurons in thalamus are dependent on calcium channel pacemaker currents for depolarization, Depolarization of thalamic neurons activates cortical neurons

Question 21

Use dependent block of sodium channels

Answer 21

See figure

Question 22

Balancing GABA and glutamate

Answer 22

In a normal neuron, excitation and inhibition are balanced

Neurons susceptible to seizure activity show enhanced excitation or decreased inhibition

Increasing GABA activity can decrease seizure activity in both situations

Decreasing Glutamate activity can also decrease seizure activity

See figure

Question 23

How does blocking the voltage-activated calcium channels work?

Answer 23

Neurons in thalamus are dependent on calcium channel pacemaker currents for depolarization

Blocking these channels slows the pacemaker

Depolarization of thalamic neurons activates
cortical neurons

Question 24

Other uses for AEDs

Answer 24

Bipolar disorder

Carbamazepine and valproate are approved

Other AEDs have shown beneficial effect (topirimate, lamotrigine, gabapentin)

Anxiety disorders

Alcohol abuse

Spasticity
Migraine, cluster headache

Neuropathic pain (especially gabapentin)

Question 25

Status epilepticus

Answer 25

medical emergency; IV diazepam (Valium) or IV lorazepam (Ativan) are used to stop the seizures.

Phenytoin may then be initiated for longer term control

Question 26

How to dose AEDs

Answer 26

Antiepileptics are gradually increased to therapeutic concentrations to minimize adverse effects and are withdrawn gradually to reduce the risk of inducing seizures

Question 27

Additional considerations when giving AEDs

Answer 27

Blood level monitoring (maintain therapeutic levels)

Pregnancy (AEDs can harm fetus, but so can uncontrolled seizures, lowest effect dose should be used, only one drug at a time, monitor blood levels)

Oral contraceptives (enhanced metabolism)

Vitamin D metabolism (can cause osteomalacia - softening of bones)

Enhanced vitamin K metabolism (can cause bleeding disorders)

Enhanced metabolism of other anti-epileptics