Epileptic Seizures: Classification and Diagnostic Approach

Question 1

Define seizure

Answer 1

A transient, involuntary change in behaviour or neurological status due to abnormal activity of populations of CNS neurones

Question 2

Define hypersynchronous

Answer 2

All neurons firing at the same time

Question 3

What are the two classifications of seizures?

Answer 3

Status epilepticus

Cluster seizures

Question 4

Outline the characteristics of status epilepticus seizures

Answer 4

Prolonged seizure activity
>5 mins
>30 mins –> brain damage
Life-threatening emergency

Question 5

Outline the characteristics of cluster seizures

Answer 5

> 2 seizures in 24 hours

Question 6

What are the 4 stages of a seizure?

Answer 6

1. Prodrome
2. Aura
3. Ictus
4. Post-ictal

Question 7

What occurs during the prodrome stage of a seizure?

Answer 7

Behaviour changes hours-days before a seizure

Question 8

What happens during the aura stage of a seizure?

Answer 8

Sensory experience just before the seizure (unproven in animals)

Question 9

What happens during the ictus stage of a seizure?

Answer 9

The seizure itself

Question 10

What happens during the post-ictal stage of a seizure?

Answer 10

Neurological changes hours-days after the seizure

Question 11

What events can appear similar to a seizure?

Answer 11

Syncope
Narcolepsy
Pain
Vestibular syndrome
Movement disorder

Question 12

What can stimulate narcolepsy?

Answer 12

Food
Excitement
Pharmacological

Question 13

How does syncope differ from a seizure?

Answer 13

Partial-complete unconsciousness
No motor activity
No post-ictal signs
Shorter in duration

Question 14

What breeds are predisposed to movement diorders that mimic seizures?

Answer 14

Scotties
CKCS
Norwich terries
Boxers
Bichon frise

Question 15

Outline the features of a epileptic seizure…

Answer 15

Lasts about a minute
Several stages
Tends to occur at rest
Rhythmic muscle contractions
Recurrent seizures respond to antiepilectic drugs

Question 16

How can seizures be classified by aetiology?

Answer 16

Structural/intracranial
Reactive/extrcranial
Idiopathic

Question 17

Give three examples of reactive/extracranial causes of seizures

Answer 17

Electrolyte imbalances (hyper or hyponatraemia, hypocalcaemia)
Hypoglycaemia 
Organ dysfunction (Hepatic encephalopathy)

Question 18

What species and age suffer from idiopathic epilepsy?

Answer 18

Dogs 6m-6y

Cats

Question 19

What breed of horse suffers from congenital seizures and how is it treated?

Answer 19

Arabs - no tx necessary as they grow out of it.

Question 20

What syndrome can causes seizures in foals?

Answer 20

Perinatal asphyxia

Question 21

What can cause seizures in adult horses?

Answer 21

Structural or metabolic brain disease
Migrating parasites or trauma
Intra-carotid injections

Question 22

What is the most likely cause of a seizure in a <6m dog?

Answer 22

Metabolic - PSS or hypoglycaemia

Infectious

Question 23

What is the most likely cause of seizures in a dog 6m-6y

Answer 23

Idiopathic

Inflammtory/infection

Question 24

What are the most likely causes of seizures if the animal appears normal inbetween episodes?

Answer 24

Idiopathic

Metabolic

Question 25

What are the most likely cause of seizures if the animal appears asymmetrically abnormal between episodes?

Answer 25

Inflamm/infection

Neoplasia

Question 26

What diagnostic tests are used to assess extracranial causes of seizures?

Answer 26

CBC and cytology
Biochemistry
Ammonia
Resting bile acids
Urinalysis
BP

Question 27

What diagnostic tests are used to assess intracranial causes of seizures?

Answer 27

Imaging - MRI, CT
CSF analysis - WBC, cell count, protein
Infectious agent test