Seizures

Question 1

An epileptic seizure is caused by

Answer 1

Excessive excitation of neutrons in the cerebral cortex.

Alterations in the neural environment can decrease the threshold of activation sufficient to result in a seizure.

Question 2

Neuron environment can be altered due to

Answer 2

Genetically determined factors, inflammation, oedema, pressure from SOLs

Question 3

Focal seizures

Answer 3

abnormal activity in an isolated region

• usually lateralised CSs - contralateral to seizure focus
• can secondarily generalise

Question 4

Generalised seizures cause

Answer 4

Abnormal neuronal activity in both hemispheres = loss of consciousness, bilaterally symmetrical muscle activity, recumbency ± jaw movements & autonomic signs.

Question 5

Most common type of seizures

Answer 5

generalised

Question 6

Cluster of seizures =

Answer 6

2+ in <24h

Question 7

Status epilepticus =

Answer 7

Seizure which is not self limiting.

Lasts >5mins or 2+ without complete recovery in between lasting >30mins

Question 8

Phases of seizure activity

Answer 8

1. prodrome - abnormal behaviour hrs/days prior
2. aura - initial focal sensory signs - secs/mins prior
   - Agitation. Hide away or may seek their owner.
3. ictus - seizure
4. Post ictal signs - hrs/days after. Disorientation, ataxia, proprioceptive deficits, blindness, pacing, polyphagia, aggression.

Question 9

Causes of seizures can be

Answer 9

Intra-cranial or extra-cranial

Question 10

Extra-cranial seizures

Answer 10

response of the ordinary brain to insults from inside the body (metabolic) or outside (toxins) - altered composition of blood flowing through the brain triggers a seizure

Question 11

Intra-cranial seizures

Answer 11

Structural brain lesion or a functional disorder e.g. idiopathic epilepsy.

Question 12

Ddx intra-cranial lesions

Answer 12

Haemorrhage or infarction
Meningitis/meningoencephalitis
Trauma (at time or 3-6mo later)
malformation, hydrocephalus
Neoplasia - e.g. glioma, meningioma
Lysosomal storage dz

Question 13

Only definitive test that an event is a seizure

Answer 13

EEG during episode

Question 14

Hx to help determine if the event is a seizure

Answer 14

• Post-ictal behaviour changes?
• Muscle tone - generally increased in seizures and ‘floppy’ in syncope
• Autonomic signs?
• Can the animal be distracted during the episode?

Question 15

Potential cause of seizures esp. in older cats

Answer 15

hypertension

Question 16

Indications for advanced imaging

Answer 16

<6mo or >6yrs
cluster seizures or status epileptics
intra-ictal deficits consistent with a forebrain lesion
refractory to drug tx despite adequate serum levels

Question 17

Stages of idiopathic epilepsy dx.

Answer 17

Stage I:
▪ 2+ unprovoked seizures >24hrs apart
▪ Onset 6mo-6yrs
▪ Normal inter-ictal physical & neurological exam
▪ No abnormalities on haematology, biochemistry, urinalysis

Stage II: stage I + unremarkable bile acid stim, brain MRI & CSF analysis

Stage III: I, II + consistent EEG abnormalities.

Question 18

Goals for epileptic management

Answer 18

Overall QOL most important

Reasonable aim = 1 short, self limiting seizure every 3mo.

Question 19

Guidelines for starting anti-epileptic drug therapy (5 points)

Answer 19

▪ 2+ seizures in 6mo
▪ Increasing fr./severity
▪ Cluster seizures or status epilepticus
▪ An underlying progressive disease causing them
▪ Severe post-ictal signs e.g. aggression or blindness.

Question 20

Anti-epileptic drug options

Answer 20

Phenobarbitone - licensed mono therapy
Potassium Bromise (NOT cats) - refractory to phenobarbitone tx
Imepitonin
Levetriacetam - may be useful if routine cluster seizures
Diazepam - rectal formula for owners to give at home for a seizure >2-3mins

Question 21

Phenobarbitone

Answer 21

Licensed monotherapy for idiopathic epilepsy

Question 22

Potassium bromide

Answer 22

Licenced for use in dogs with idiopathic epilepsy refractory to phenobarb tx
Can induce vomiting, pancreatitis & aggression.

Question 23

Imepitoin

Answer 23

Licenced monotherapy in dogs with idiopathic epilepsy.

Don’t use if hx of cluster seizures or status epilepticus - poor efficacy.

Question 24

Levetriacetam

Answer 24

May be useful in dogs routinely showing cluster seizures. Used immediately following 1st seizure.
Aim - reducing number + severity of further seizures in the cluster

Question 25

Diazepam

Answer 25

Rectal formula can be dispensed for the owner to give at home with a seizure lasting more than 2-3mins.