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Define seizures

- transient involuntary change in behaviour or neurological status d/t abnormal activity of populations of CNS neurons
- hypersynchronous firing of neurons
- d/t imbalance of excition and inhibition
- specific seizures are named after their lcinical signs


How are seziures classified? How should they not be classified in vet?

- classify by clinical sign
- NOT petit-mal grand-mal (petit mal = focal absent seizure in humans, grand-mal = generalised tonic clonic)


Are seizures in thems in themselve sharmful to the brain? 1* dmaage?

NO unless >30mins (then focal and general both harmful)
1* damage is very little
2* dmaage more important
- hypoxia
- hypercarbia
- hyperthermia
- others...


What types of MRI can be used for looking at the brain?

T1W fat is white
T2W fat and water is white
Flair flowing structures/liquid (not visable or white??!)


How can seizures be classified?

> focal
- simple focal (no loss of conciousness)
- complex focal (impaired conciousness)
- focal seizure with 2* generalisation
> generalised seizures
- Convulsive
- Non-convulsive
> status epilepticus
- prolonged seizuring
- >30 mins according to basic science -> damage
- clinical >5mins seizuring = unlikely to be self limiting


If limbic structures are involved in seizure activity is this easy or hard to tx? What else can affect ease of tx?

- hard
- length of seizure - longer they go on, more difficult they are to tx


Define epilepsy

>2 seizures
>48hrs apart


What are the stages of tx classified as?

> prodrome
- behaviour changes that occour hours/days before the seizure
> aura
- sensory/focal onset seizures may start with sensory experience eg. smell or feeling of deja vu.
- hard to prove in animals but behaviour change often seen minutes before ictus
> ictus
- sezire
> post-ictal
- neuro alterations hourse/days after ictus
- cf. vestibular/syncope (??) causes with no post-ictal phase


How else may seizures be classified?

> Self limiting
- focal (sensory/motor/automatisms most common orofacial "chewing gum fits")
- generalised (tonic-clonic/clonic/myoclonic/atonic)
> Clustered or continuous (status epilecpticus)
- focal (motor: epileptia partialis continua; sensory: auro continua (hard to dx animals)
- generalised
> reflexive
- precipitating stimuli eg. loud bang


What things may be seen with seizures? (random notes!)

- Hypersalivation
- loss of proprioception -> rearing up backwars etc.
- vocalisation in cats


Are seizures conciously perceived?

Focal yes, generalised not concious no


When do seizures often occour?

- when asleep


Does a focal motor seizure involve the cortex? Eg. leg twitch



Ddx for seizures (what can mimic seizure like behaviour?)

> syncope
- partial/complete loss of consciousness
- lack of motor activity
- no post ictal signs
- shorter duration
> narcolepsy
- v rare
- stimulated by excitement, food or pharmacologically
> pain
> vestibular syndrome
> movement disorders
- scotty cramp (excercise in/dependent, no salivation, concious)
- CKS tetany, hypertonicity and deer-stalking
- norwich terriers
- Boxers paroxysmal dystonic choreoathetosis
- Bichon frise similar to boxers


How does position of disk extrusion in the spine alter clinical severity>

Cervical spine majority of disk can be extruded before myelopathy seen in neck


Typical history with seizures

- last ~1min
- several stages
- often at rest or asleep
- clonic movement (rhythmical muscle contraction) common in partial and generalised seizure
- MOST recurrent seizures respond at least partially to AEDs
- EEG?


Can anyone seziure?

Yes just different thresholds


How can seizures be classfiied by aetiology?

1. type of seizure
> symptomatic/2* seizure
- structural brain dz
- assymmetric
> reactive seizure
- metabolic/ toxic cause
- remove 1* cause and will stop
> idiopathic/1* epilepsy
- genetic cause
- generlised seizures
> possible symptomatic/cryptogenic seizure
- R/o only via PME
- PE abnormlaities but imaging normal
2. branching diagram
> intra v extra cranial
- Intra = functional (idiopathic) or structural (possible symptomatic epilepsy)
- extra = intrinsic (metabolic reactive seizures) or extrinsic (toxic reactive seizures) + further subdivisions!!


What are the subdivisions of extracranial epilepsy Ddx?

> electrolyte imbalance
- hypernatraemia
- hyponatraemia
- hypocalcaemia
> energry deprivation
- thiamine deficiency
- hypoglycaemia
> organ dysfunction
- uraemic encephalopathy
- hepatic encepalopathy


WHat are the subdivisions of intra-cranial epilepsy ddx?

> Cryptogenic (eg. head trauma years earlier, normal imaging)
> Symptomatic
- Anomalous (hydrancephaly, lissencephaly, arachnoid cyst)
- Neoplastic (meningioma, astrocytoma, oligodendroglioma, ependymoma, choroid plexus tumour)
- Infectious (Viral, bacterial, parasitic, fungal, rickettsial, protozoal)
- Inflammatory (Granulomatous meningo-encephalomyelitis, eosinophilic meningoencephalitis, other meningoencephalitides eg. pug encephalitis)
- traumatic
- Vascular (ischaemia, haemorrage d/t coagulopthy or hypertension)
> Idiopathic
- ion channel mutation
- other genetic mutations


Typical signs associated with idiopathic epilepsy

> dogs
- 6month - 6 years
- generalised seizures (beagles, GSD, lab/ret, gold ret, bermese mountain, belgain tervuerens, keeshonds, irish wolfhounds)
- some breeds mainly partial seizures +- 2* generalisation (vizlas, english springer spaniels, danish labradors, lagotta romagnolo, standard poodles, finnish spitz)


Any pdf in horses for epilepsy/seizures?

- congenital in arab foals (will grow out of it)
- perinatal asphyxia (neonatal maladjustment syndrome) foals
- adults often d/t structual or metabolic brain dz. eg. migrating parasites, previous trauma OR intra-carotid injection


How can signalment help refine ddx?

> 6 months - 6 yrs
- idiopathic epilepsy
- inflam/infectious
- metabolic
~neoplasia, toxin, trauma
> >6yrs
- neoplasia
- idiopathic late onset
- inflam/infectious
- ~metabolic (HE, hypoglycaemia 2* to insulinoma)
~ toxic/trauma


How can disease onset and progression help narrow down ddx?

- inflam/infectious/neoplasia and generative dz. worsens over time
- metabolic is fluctuating
- trauma and vascular improves over time


How can inter-ictal exam findings narrow down Ddx?

> Normal
- idiopathic
- metabolic
- neoplasia in silent area of brain or early dz
> abnormal symetircal
- metabolic
- toxic
- hydrocephalus
- degenerative dz
- midline structural eg. pituitary neoplasia
- ?!cave - post ictal?! no idea waht this means
> abnormal ASYMMETRICAL [laterialising]
= intracranial
- neoplasia
- inflam/infectious
- anomalies


How can lateralising (asymetircal) v symmetrical seizures narrow Ddx?

> symetrical generalised onset
- idiopathic
- metabolic
- toxic
- degenerative
- hydrocephalus
- trauma
- midline structural
> asymetirical focal onset
- inflam/infectious
- neoplasia
- anomalies
- trauma
-cryptogenic and idiopathic


Extra cranial further diagnostics

> minimum database
- CBC and cytology
- biochem
-+ amonia
- resting BA or dynamic BA in smallies
- urinalysis (not common horses)
- BP (esp cats - cardiac work up)
> further diagnostics
- depending on signament, hx and PE
- infectious agents specific


Intracranial further diagnostics

> imaging
- CT
> clinical pathology
- CSF (WBC count, differential cell count, protein content)
- positive brain imaging/inflammatory CSF
- infectious agent testing