Seizures (Yr 4)

Question 1

what is a seizure?

Answer 1

transient occurrence of convulsions or focal motor, autonomic or behavioural signs due to abnormal excessive or synchronous epileptic neural activity in the brain

Question 2

where do seizures localise to?

Answer 2

forebrain

Question 3

what are some possible changes seen if a lesion is localised to the forebrain?

Answer 3

seizures
behavioural change
compulsive circling/pacing
head turn on same side as lesion
loss of vision on opposite side as lesion
postural reaction deficits on opposite side

Question 4

what is the pathogenesis that leads to seizures?

Answer 4

excessive excitation or decreased inhibition

Question 5

what is the main excitatory neurotransmitter?

Answer 5

glutamate

Question 6

what is the main inhibitory neurotransmitter?

Answer 6

GABA

Question 7

what are the stages of seizures?

Answer 7

prodrome
aura
ictal
post-ictal

Question 8

what is the prodrome phase of a seizure?

Answer 8

any predictive or preceding events to the seizure

Question 9

what is the ictal phase of a seizure?

Answer 9

the actual seizure event - involuntary muscle tone/movement with abnormal sensations or behaviour

Question 10

what is the post-ictal phase of a seizure?

Answer 10

minutes to days after the event that can be characterised by unusual behaviour or neurological deficits

Question 11

how long do ictal events usually last?

Answer 11

60-90 seconds

Question 12

when do seizures most commonly occur?

Answer 12

at sleep/rest

Question 13

how can ictal events often be distinguished from other paroxysmal activity?

Answer 13

ictal events have autonomic signs, such as there will spray urine rather than the passive dribbling you may get with paroxysmal activity

Question 14

what are the two main phenotypic categories of seizures?

Answer 14

generalised
focal

Question 15

what parts of the forebrain do generalised seizures involve?

Answer 15

both cerebral hemispheres

Question 16

what are the phases possible with generalised seizures?

Answer 16

tonic-clonic
tonic
clonic
myoclonic
atonic

Question 17

what is the most common phase associated with generalised seizures?

Answer 17

tonic-clonic

Question 18

what is a tonic-clonic generalised seizure phenotype?

Answer 18

animal initially appears stiff/opisthotonic followed by twitching/jerky movements

Question 19

what is a myoclonic generalised seizure?

Answer 19

a brief shock like muscle action

Question 20

what are the forms of focal seizures?

Answer 20

motor
autonomic
behavioural

Question 21

what animals is audiogenic reflex seizures seen in?

Answer 21

older (>15 years old) cats
(majority of cats are deaf)

Question 22

what causes audiogenic reflex seizures?

Answer 22

they are consistently precipitated by environmental or internal stimuli (typically sounds)

Question 23

what is usually an effective treatment for audiogenic reflex seizures?

Answer 23

levetiracetam

Question 24

what type of seizure is a feline audiogenic reflex seizure?

Answer 24

mycolonic (jumpy) that can progress to generalised tonic-clonic seizures

Question 25

what are some differential diagnoses for seizures?

Answer 25

narcolepsy/cataplexy neuromuscular collapse syncope paroxysmal dyskinesia painful episodes metabolic disease vestibular disease idiopathic head tremor syndrome

Question 26

what is idiopathic head tremor syndrome?

Answer 26

not a seizure but involuntary head movement that can be vertical or horizontal, they are caused by stress and can be stopped by distracting the dog

Question 27

what breed is episodic hypertonicity seen in?

Answer 27

cavalier King Charles spaniel

Question 28

what is cataplexy?

Answer 28

an acute loss of muscle tone

Question 29

how can narcolepsy-cataplexy often be elicited?

Answer 29

giving food (dog feels overwhelmed)

Question 30

what are the three causes of seizures?

Answer 30

reactive idiopathic structural

Question 31

what are reactive seizures?

Answer 31

seizures occurring as a natural response from the normal brain to a transient disturbance in function (usually have concurrent neurological signs)

Question 32

what are the two common causes of reactive seizures?

Answer 32

metabolic intoxication

Question 33

what is the presumed causes of idiopathic seizures?

Answer 33

presumed to be genetic

Question 34

what is structural epilepsy?

Answer 34

epileptic seizures which are provoked by intracranial or cerebral pathology (inflammation, neoplasia, trauma...)

Question 35

how is idiopathic epilepsy diagnosed?

Answer 35

diagnosis of exclusion

Question 36

what age is idiopathic epilepsy usually seen in dogs?

Answer 36

6 months to 6 years old

Question 37

how do dogs with idiopathic epilepsy appear between seizures?

Answer 37

normal, with no neurological signs

Question 38

when should you MRI dogs with suspected seizures?

Answer 38

if the age of onset is <6 months or >6 years inter-ictal neurological abnormalities status epilepticus or cluster seizures previous presumptive diagnosis of idiopathic epilepsy

Question 39

when should you start treating seizures?

Answer 39

if they have structural/metabolic epilepsy status epilepticus or cluster seizures inter-ical period is less than 6 months post-octal signs are severe seizure frequency/duration is increasing first seizure is within one month of trauma

Question 40

what drugs are licensed to treat seizures in cats?

Answer 40

none licensed

Question 41

what are the drugs available to treat seizures?

Answer 41

phenobarbital bromide (potassium or sodium) imepitoin

Question 42

what is the mechanism of action of phenobarbital?

Answer 42

increases the inhibitory effect of GABA by prolonging the chloride channel opening

Question 43

how and why do we need to monitor animals on phenobarbital?

Answer 43

do biochemistry/haematology at 2 weeks, 3 months and 6 months check for effects on liver

Question 44

what are the possible side effects of phenobarbital?

Answer 44

sedation/ataxia PU/PD, polyphagia hepatotoxicity haematological abnormalities (neutropenia, anaemia...) pseudolymphoma

Question 45

where is phenobarbital metabolised?

Answer 45

in the liver by cytochrome P450 enzymes (these enzymes can be unregulated so may have to increase the phenobarbital dose over time)

Question 46

what is the mechanism of action of bromide is seizure control?

Answer 46

competes with chloride transport across nerve cell membranes and inhibits sodium transport so the membrane become hyperpolarised to increase the seizure threshold

Question 47

can potassium bromide be used in cats?

Answer 47

no (it will kill them)

Question 48

how is bromide metabolised?

Answer 48

it is excreted unchanged in the urine

Question 49

what are possible side effects of bromide?

Answer 49

sedation, ataxia, paresis bromism

Question 50

what types of seizures should emepitoin not be used for?

Answer 50

cluster seizures or structural epilepsy

Question 51

what is the mechanism of action of imepitoin?

Answer 51

partial agonist for the benzodiazepine binding site of GABA receptors

Question 52

where is imepitoin metabolised?

Answer 52

liver

Question 53

why should potassium bromide be avoided in cats?

Answer 53

can cause eosinophilic bronchitis