Seizures (Holgar)

Question 1

Define seizures

Answer 1

• 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

Question 2

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

Answer 2

• classify by clinical sign

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

How can seizures be classified?

Answer 5

> 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

Question 6

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

Answer 6

• hard

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

Question 7

Define epilepsy

Answer 7

> 2 seizures

>48hrs apart

Question 8

What are the stages of tx classified as?

Answer 8

> 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

Question 9

How else may seizures be classified?

Answer 9

> 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

Question 10

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

Answer 10

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

Question 11

Are seizures conciously perceived?

Answer 11

Focal yes, generalised not concious no

Question 12

When do seizures often occour?

Answer 12

• when asleep

Question 13

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

Answer 13

No

Question 14

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

Answer 14

> 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

Question 15

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

Answer 15

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

Question 16

Typical history with seizures

Answer 16

• 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?

Question 17

Can anyone seziure?

Answer 17

Yes just different thresholds

Question 18

How can seizures be classfiied by aetiology?

Answer 18

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!!

Question 19

What are the subdivisions of extracranial epilepsy Ddx?

Answer 19

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

Question 20

WHat are the subdivisions of intra-cranial epilepsy ddx?

Answer 20

> 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

Question 21

Typical signs associated with idiopathic epilepsy

Answer 21

> 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)

Question 22

Any pdf in horses for epilepsy/seizures?

Answer 22

• 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

Question 23

How can signalment help refine ddx?

Answer 23

>  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

Question 24

How can disease onset and progression help narrow down ddx?

Answer 24

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

Question 25

How can inter-ictal exam findings narrow down Ddx?

Answer 25

> Normal
- idiopathic
- metabolic
- neoplasia in silent area of brain or early dz
-toxic
> 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

Question 26

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

Answer 26

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

Question 27

Extra cranial further diagnostics

Answer 27

> 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

Question 28

Intracranial further diagnostics

Answer 28

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