Neuro - seizures Flashcards by Mary Tilling

What causes seizures?

Neurones are excitable cells and can depolarise
When the excitatory state is not balanced with the inhibitory state then can get seizures

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What is a seizure threshold?

Brain activity fluctuates between excitatory and inhibitory stimulation
Threshold where excitatory stimulation is enough to start synchronous activation of neurones

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What is the definition of a seizure?

Fit=episode=moment
Change in mentation and autonomic function over a period of time

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What is the definition of an epileptic seizure?

Abnormal uncontrollable hypersynchronous activation of a large group of neurones

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What is epilepsy?

Recurrent epileptic seizures - always forebrain neurolocalisation

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What is status epilepticus?

Seizure for longer than 5 mins
Or 2 seizures without complete recovery in between
Emergency action required - seizure longer than 5 mins lead to brain damage

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What are cluster seizures?

2 or more seizures in 24hr period with complete recovery in between

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What are the different types of seizures?

Partial/focal seizure
Generalised seizures
Partial with secondary generalisation

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What is a partial/focal seizure?

Affects a well defined area
May not have loss of consciousness/awareness

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What is the most common type of seizure?

Generalised seizure - tonic-clonic
Change in behaviour/consciousness/absence

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What does tonic-clonic mean?

Tonic - prolonged extension
Clonic - alternating flexion and extension

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What are the phases of the classic generalised tonic-clonic seizure?

Pre-ictal phase - period before the seizure, behaviour changes
Ictus - seizure, non responsive, tonic clonic movements, autonomic signs
Post ictal phase - mins to days afterwards, disorientation, polyphagia, ataxia, blindness

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What can trigger seizures?

Stress
Excitement
Flashing lights
Noises

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What are some seizure mimics?

Narcolepsy/cataplexy - conscious, quick loss of muscle tone
Fly catching - dog doesnt look consciousness
Movement disorder
Syncope - very quick, dog immediately back to normal
3rd degree AV block - not enough blood to brain

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What are the features of movement disorders that distinguish them from seizures?

Responsive/conscious
Often longer than 5 mins - sometimes hours
No autonomic signs - salivating, defecating

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What is an example of a movement disorder?

Border terrier epileptoid cramping syndrome (spikes disease) - running along skipping occasionally with leg lifting into the air

What are the differentials for seizures? Use localisation to help

Extra-cranial - toxins, metabolic
Intra-cranial - structural, functional

What are the signs of toxin induced seizures?

Often accompanied by GI signs - vomiting and seizures

What are common toxins causing seizures?

Ethylene glycol - antifreeze
Permethrin spot on in cats
Ivermectins in collies

What are 3 causes of metabolic induced seizures?

Portosystemic shunt/liver failure - causing hepatic encephalopathy
Hypoglycaemia - liver dysfunction, toy breeds, insulinoma
Hypocalcaemia

What are 3 structural intracranial causes of seizures?

Brain tumour
Inflammation
Hydrocephalus

What is a functional intracranial cause of seizures?

Idiopathic epilepsy

How is idiopathic epilepsy diagnosed?

Rule out all other options first
Recurrent seizures in animal between 6 months and 6 years
Normal inter-icteral neurological exam
Normal metabolic investigation

What is the minimum database following an isolated seizure?

Haem
Biochem
Fasted blood glucose
Isolated bile acids test - pre and post prandial

What are the goals of seizure management?

Stop patient seizuring in emergency management Reduce seizure frequency Reduce severity With acceptable side effects and costs for owner, and is practical

When do you start treatment in a seizuring animal?

If more than 1 seizure per month Increasing frequency Cluster seizures or status epilepticus If there is underlying structural or metabolic cause

When is just monitoring appropriate for a seizuring animal?

Single seizure Long interictal period - more than 3 months Known toxic trigger

What type of drug can you use as emergency management to treat seizures?

Anti-convulsants - very short half life, short acting rapid onset of action Stops a seizure when it is occuring

What are some examples of anti-convulsants?

Diazepam - first line IV/rectally (not IM) Midazolam Propofol

How often can you give anti-convulsants in an emergency?

Can repeat diazepan/midazolam dose up to 3 times or until seizure stops

What type of drug do you use for long term management of seizures?

Anti-epileptic - longer half life, slow onset of action, long acting

What are some examples of anti-epileptic drugs?

Phenobarbitone - first choice Imepitoin - second choice (doesnt treat status epilepticus or cluster seizures) Adjunct - potassium bromide (not in cats)

When should you consider referral for advanced imaging in seizure cases?

Very young or old dog Not normal between episodes Status epilepticus

What is the mechanism of action of an anticonvulsant?

Reduces excitation and promotes inhibition - act on GABA

When do you add a second antiepileptic drug?

Improper seizure control Causes side effects if increasing first line drug means reaching toxic blood level (best to use one drug though)

When should you monitor seizure drug control?

At steady state - 3 weeks after starting, then every 6-12 months If seizure control is lost If signs of toxicity

What is uncontrolled epilepsy? What percentage of patients have this?

When still seizure the same amount even after treatment - 20-30% of patients

What are the 5 steps of managing acute seizures?

Check vital parameters Time it Protect patient Try to get IV access Check blood glucose/get blood sample Givve anticonvulsant - IV, rectally