Investigation + management of seizures Flashcards
1
Q
What are the different seizures?
A
- Epileptic seizure = sudden, transient paroxysmal event caused by excessive +/or hypersynchronous firing of neurons in the brain
- Reactive seizures = seizures with extracranial cause (toxin, metabolic disease …)
- Cluster seizures = more than one seizure in 24hr period BAD
- Status epilepticus = seizure lasting >5mins / 2 or more discrete seizures without full recovery in between = LIFE THREATENING
2
Q
Why is seizures relevant?
A
- Most common neurological presenting sign in small animal practice
3
Q
What are stages of a seizure?
A
- Prodromal = predictive / preceding events
- Aura = initial manifestation of a seizure
- Ictal phase = actual seizure
-less than 2 mins, occurs usually at rest/sleep
-hypersalivation, mydriasis, involuntary urination / defecation - Post ictal-phase = behavioural +/or neurological abnormalities post seizure = can last minutes/days
4
Q
What causes a seizure?
A
- Imbalance between excitation + inhibition
-Glutamate = excitatory
-GABA = inhibitory
5
Q
What are different location of seizures?
A
- Generalised =
-both cerebral hemispheres
-tonic-clonic
-myoclonic
-atonic - Focal seizures =
-unilateral seizures w/ without 2ary generalisation - Complex partial seizures
6
Q
What is paroxysmal dyskinesia? (movement disorders)
A
- Recurrent episodes of involuntary movements without changes in consciousness
- Last minutes / hours
- Idiopathic + genetic causes (border terrier / CKCS)
7
Q
What does twitching of face, mydriasis + hypersalivation indicate?
A
- Focal seizure
8
Q
What are often confused for seizures?
A
- Paroxysmal dyskinesia
- Idiopathic head tremor syndrome
- Syncope
- Episodic muscle stiffness
- Narcolepsy - so excited you fall asleep
- Vestibular episodes
- Neck pain
- Nystagmus
- Tremor syndromes
- Behavioural disorders
9
Q
Where are all seizures from?
A
Forebrain
10
Q
What are signs of forebrain problems?
A
- change in behaviour
- compulsive pacing / circling toward lesion
- head / body turn towards lesion
- contralateral proprioception, menace, nasal-mucosal sensation
11
Q
What is initial assessment of seizure patients?
A
- Hx = accurate description of episode (video) any other abnormalities
- Examination =
-abnormal asymmetrical = structural lesion
-abnormal symmetrical = post-ictal, metabolic / bilateral structural lesion - Bloodwork = rule out extra-cranial causes (+bile acid stim - to rule out PSS)
- MRI + CSF = indicated if asymmetrical neurological deficit
12
Q
What can happen if you don’t treat seizures?
A
- Secondary effects =
-sudden unexpected death in epilepsy
-aspiration pneumonia
-soft tissue / orthopaedic injuries - Late effect =
-structural brain atrophy
-progressive cognitive impairment
-anxiety
13
Q
When would you treat seizures?
A
- More than one seizure in a six-month period (dogs) or three-month period (cats)
- Cluster seizures or status epilepticus EMERGENCY
- Suspicion or diagnosis of a structural lesion
- Seizure within three months of a traumatic brain injury
- Severe/prolonged post-ictal signs (aggression, blindness etc)
- Decreasing frequency or worsening seizure intensity over three inter-ictal periods
14
Q
How do you treat seizures?
A
- Enhance inhibitory by facilitating GABA
- Reduce excitatory transmission
- Modulate cell membrane cation conductance
(Drugs must be able to cross BBB)
15
Q
What drugs can be used? SIDE EFFECTS?
A
- Phenobarbitone = promotes GABA (IV, IM, PO)
-can cause hepatic injury
-aim for serum levels of 25-32mg/l
-AE = polyphagia, polyuria, polydipsia, ataxia, lethargy
-less common AE = hepatotoxicity, pseudolymphoma, hypothyroidism, dermatological abnormalities - Bromide = increase seizure threshold (PO / per rectum)
-use for dogs as ADD on (NEVER IN CATS)
-AE = ataxia, lethargy, polyphagia, polydipsia, polyuria
-less common AE = pancreatitis, panniculitis, muscle pain - Imepitoin (PO only) GABA promoter
-AE = polyphagia, hyperactivity, polydipsia, polyuria
-less common AE = lethargy, GI signs, ataxia, noise sensitivity - Levetiracetam = reduces glutamate (IV, SC, IM, PO + per rectum)
-SAFE + well tolerated
-AE = mild sedation, decreased appetite
