Seizures

Question 1

What are characteristics of generalized seizures?

Answer 1

Involvement of both cerebral hemispheres simultaneously
Consciousness is impaired

Question 2

Define: Tonic-Clonic

Answer 2

Sustained increase in muscle contraction followed by repetitive involuntary muscle contractions at a frequency of 2-3 seconds

Question 3

Define: Tonic

Answer 3

Rigid limb extension

Question 4

Define: Myoclonic

Answer 4

Sudden, brief involuntary contraction of a muscle or groups of muscle

Question 5

Define: Atonic

Answer 5

A sudden loss of muscle tone

Question 6

What are characteristics of focal seizures?

Answer 6

Initial activation of one part of one cerebral hemisphere or region in the forebrain
Complex focal seizures = altered consciousness

Question 7

Define: Reactive Seizure

Answer 7

Seizure occurring as a natural response from the normal brain to a transient disturbance in function
Metabolic or toxic

Question 8

Define: Structural Epilepsy

Answer 8

Epileptic seizures which are provoked by intracranial or cerebral pathology
Inflammatory, neoplastic, traumatic

Question 9

Define: Idiopathic Epilepsy

Answer 9

Genetic or presumed genetic in origin
No inter-ictal neurological signs

Question 10

How is idiopathic epilepsy diagnosed?

Answer 10

Dx of exclusion
2 or more seizures >24h apart
6m to 6y of age
Normal inter-ictal
No cbc/chem/ua abnormalities
Family history of IE

Question 11

When should a seizuring patient be MRI’d?

Answer 11

<6m or >6h
Interictal abnormalities
Status epilepticus or cluster seizure
Previous presumptive diagnosis of IE and drug-resistance

Question 12

When should seizures be treated?

Answer 12

Structura epilepsy or reactive seizures
Status epilepticus or cluster seizures
>2 seizures in 6m period
Post-ictal signs severe or last longer than 24h

Question 13

What is the mechanism of action of phenobarbital?

Answer 13

Augments the inhibitory effect of GABA, prolonging the chloride channel opening at gaba a receptors

Question 14

When should pts on phenobarbital be monitored?

Answer 14

Serum 2-3w post dose change
CBC/Chem/BA: 6w, 6m

Question 15

How is phenobarbital metabolized?

Answer 15

Hepatic microsomal enzymes - induces cytochrome P450 enzymes in liver

Question 16

Which AED requires a consistent diet?

Answer 16

Bromide

Question 17

What is the mechanism of action of bromide?

Answer 17

Competes with chloride transport across nerve cell membranes and inhibits sodium transport = membrane hyperpolarization which raises the seizure threshold

Question 18

How is bromide metabolized?

Answer 18

Excreted unchanged in the urine
Undergoes tubular reabsorption in competition with chloride

Question 19

What is the AED of choice for PSS/liver disease?

Answer 19

Levetiracetam
Renal excretion

Question 20

What is the mechanism of action of zonisamide?

Answer 20

Blocks propagation of epileptic discharges

Question 21

How does the drug dose of zonisamide change when used in conjugation with other AEDs?

Answer 21

Reduce phenobarbitone doses by 25% when starting zonisamide

Question 22

Diazepam usage in cats

Answer 22

Fulminant hepatic necrosis with oral administration

Question 23

Potassium bromide usage in cats

Answer 23

Contraindicated = eosinophilic bronchitis

Question 24

Propofol usage in cats

Answer 24

Heinz body anemia

Question 25

What situations are considered emergency with seizures?

Answer 25

Cluster seizures (2 or more within 24h) Status epilepticus (>5min, >2 seizures without recovery)

Question 26

When does neuronal damage occur in seizures?

Answer 26

After 30 - 60 minutes *Excitotoxic cell injury*

Question 27

1st line drugs for emergency seizure control

Answer 27

Diazepam Midazolam

Question 28

What medications should be started *after* emergency seizure control?

Answer 28

Phenobarital Status or clusters: phenobarbital IV loading Further seizures: levetiracetam loading dose

Question 29

When should infusions be used? What drugs are used?

Answer 29

For breakthrough seizures Diazepam, midazolam, propofol

Question 30

What occurs after 30 minutes in status epilepticus? What drug can be used?

Answer 30

An alteration in the GABA A receptor subunit expression occurs with NMDA receptor ACTIVATION (which is the major mediator of excitotoxicity). Ketamine can be considered