Seizures

Question 1

Describe a seizure.

Answer 1

Aura - pre-ictal - ictal event - post-ictal

Ictal event typically lasts 60-90s
Loss of continuousness
Commonly occurs at rest
Autonomic signs may occur after a seizure

Tonic clonic seizures are most common in animals - paddling

Question 2

What are the three types of focal seizure?

Answer 2

1. Motor - eg excessive licking
2. Autonomic - excessive salivation, LN enlargement
3. Behavioural - catching flies, stopping and staring

Question 3

Describe an audiogenic seizure in a cat.

Answer 3

Old cats, 15yo
Reflex seizure that occurs in response to high frequency sounds
Myoclonic seizure that frequently progresses to a tonic clonic seizure

Control- levitiracetam

Question 4

Differential diagnoses for seizures?

Answer 4

Narcolepsy
Cataplexy
Syncope
Movement disorder
Metabolic disease 
Vestibular disease

Question 5

What movement disorders are there?

Answer 5

Head tremors
Episodic falling
Canine epileptoid cramping

Question 6

Describe head tremor movement disorder

Answer 6

Dobermanns and English Bulldogs

Head nod - yes or no, never yes and no in the same event
May last hours
Can be distracted

Question 7

What is he common presentation of episodic falling?

Answer 7

CKCS
Increased tone in the limbs until the animal falls over
Occurs during exercise
Responsive to diazepam

Question 8

What is canine epileptoid cramping?

Answer 8

Paroxysmal dyskinesia - unable to move and becomes very stiff
Responds to the owner
Thought it be linked with a gluten intolerance in Border Terriers
May cause v+ and d+
Dx: blood test
Response to a gluten free diet

Question 9

What causes of seizures are there?

Answer 9

Reactive seizures - occur during to a metabolic or toxic cause
Idiopathic - genetic
Structural epilepsy - provoked by cerebral pathology

Question 10

What are the presentations of idiopathic epilepsy?

Answer 10

Between 6mo and 6y
Suspected genetic epilepsy - collies and Belgian shepherds
Epilepsy of unknown cause - no indication of structural epilepsy

Question 11

How can you diagnose idiopathic epilepsy?

Answer 11

Tier 1 confidence interval
2 seizures more than 24hours apart
6m to 6y
Unremarkable inter ictal examination
NAD on - haematology, biochemistry, NH3, fasting bile acids, urinalysis 
Family history of idiopathic epilepsy 

Tier 2 confidence interval
Unremarkable fasting post prandial bile acids
Normal MRI of the brain
CSF analysis normal

Tier 3 confidence interval
Ictal or inter-ictal electroencephalogram abnormalities

Question 12

When should you consider performing an MRI?

Answer 12

Onset - less than 6m more than 6y
Interictal neurological abnormalities 
Status epilepticus
Cluster seizures 
Drug resistance with idiopathic epilepsy previously diagnosed

Question 13

Indications for starting treatment.

Answer 13

Structural or metabolic epilepsy
Status epilepticus or cluster seizures
Inter-ictal period of 6m or less
Post-ictal signs are severe or last longer than 24h
Seizure duration or frequency increasing
Seizures getting more severe
1st seizure within 1 m of a traumatic event

Question 14

What drugs are licensed for the treatment of epilepsy?

Answer 14

None in cats

In dogs:

1. Phenobarbitone - potentiates the action of GABA
2. KBr / NaBr - only licensed as a monotherapy
3. Imepitoin - only licensed as a monotherapy

Question 15

Describe the effects, monitoring and side effects of phenobarbitone.

Answer 15

Potentiates the effects of GABA

Monitoring
2 weeks after a dose change, 3 months and 6 months
Plain serum, haematology and biochemistry

Aim for levels - 25-30 mg/L

Side effects: sedation, ataxia, PU/PD, polyphasic, hepatotoxicity, neutropenia, anaemia and thrombocytopaenia

Question 16

Describe the effect of KBr, monitoring and side effects of KBr.

Answer 16

Competes with Cl- and inhibits Na+ transport - causes membrane hyperpolarisation

DO NOT USE IN CATS

Monitor every 12w - haematology and biochemistry - plain serum

Side effects: sedation, ataxia and pelvic limb weakness

Question 17

What other AEDs are there that aren’t licensed?

Answer 17

Levetricetam - minimal side effects

Zonisamide - ataxia, sedation, dry eye, inappetance

Question 18

Define status epilepticus.

Answer 18

Seizures lasting more than 5 minutes

2 seizures occurring without full recovery

Question 19

Define cluster seizures.

Answer 19

2 or more seizures within 24h

Question 20

What may cause status epilepticus?

Answer 20

Neoplasia
CNS inflammatory disease 
Trauma 
Metabolic disease 
Toxicity 
Idiopathic epilepsy

Question 21

What is status epilepticus an emergency?

Answer 21

Causes irreversible neuronal damage after 30mins

Tachycardia, hyperglycaemia, hypertension

Question 22

Describe the emergency management of status epilepticus.

Answer 22

1. Stop the seizure - diazepam 1mg/kg per rectum
2. History
3. Place an IV catheter - 0.5mg/kg phenobarbitone
4. Clinical examination
5. Baseline bloods - glucose, sodium, calcium, renal and liver parameters, serum AED concentration
6. Phenobarbital 3mg/kg BID

Question 23

How should you manage breakthrough seizures or if the seizures don’t stop!

Answer 23

1. Levetricetam loading - 60 mg/kg
2. Diazepam
3. Midazolam - 0.3 mg/kg IV but CI in hepatic dysfunction
4. Propofol - 6mg/kg bolus, followed by CRI
5. Ketamine infusion only if Propofol infusion failing

Question 24

What should you monitor in an emergency status epilepticus patient?

Answer 24

Heart rate and respiratory rate
BP (systolic >90, mean 70-80)
Urine production 1-2 ml/kg/h
SPO2 - greater than 95
ETCO2 - 35-40 mmHg 
Temperature 
Neurological examination 
Pharyngeal tone in patients on a CRI

Question 25

What are important to considerations when selecting AEDs in cats?

Answer 25

Diazepam - fulminant hepatic necrosis with oral administration
Propofol - Heinz body anaemia
KBr - eosinophillic bronchitis
Phenobarbitone - lower loading dose