Epilectic seizures Flashcards
What is a definition of seizures?
- Hypersynchronous - Neurons firing at the same time
- Transient + involuntary change in behaviour/neuro status due to abnormal behaviour + overpopulation of neurons
- Imbalance between excitation and inhibition
How are seizures classified?
Classified by clinical signs
What are the 2 groups of seizure classification?
Focal and generalised seizures
What are the different types of Focal seizures?
- Simple focal - no loss of consciousness
- Complex focal - loss of consciousness
- Focal seizure with secondary generalisation
Focal occurs on one side of the brain
Brain usually good at stopping seizures after 1-2mins - struggles after 10mins
What are the different types of Generalised seizures?
Generalised seizures occur all over the two sides of the brain
- Convulsive
- Nonconvulsive
What is a Status Epilepticus?
- Prolonged seizure activity
- > 5mins (clinical)
- > 30mins causes brain damage - too diff to tx - can be life threatening
What is a Cluster seizure?
- > 2 seizures in a 24 hours period
- Serious
What are the 4 different stages of a seizure?
- Prodrome - behaviour changes occurring hours/days before seizure
- Aura - sensory/focal onset seizures - sensory experience - déjà vu - hallucinations - (hard to prove)
- Ictus - the seizure itself
- Post-ictal - neurological status alterations hours/days after the seizure
What self-limiting focal and generalised seizures are there?
- Focal: Sensory, Motor, Automatisms (repeated behaviour eg. orofacial automatisms - chewing gum fits)
- Generalised: Tonic-clonic, clonic, myoclonic, atonic
Clonic - rhythmic muscle contractions
What types of cluster/continuous seizures are there?
Focal: motor (epilepsia partalialis continua), sensory: aura continua - diff to characterise in dogs
What are a type of reflexive seizure?
Precipitating seizure (epilepsy)
If an animal is twitching on one side, is the lesion on the same side?
No lesion in forebrain on the opposite side
What are some common behaviours in seizuring animals?
- Lip smacking
- hypersalivating
- howling
- fly catching (Limbic system)
- chronic movement in legs (motor cortex)
Horse- going backwards - v dangerous
What different events can mimic seizures?
- Syncope - partial/complete loss of consciousness, lack of motor activity, no post-ictal signs, shorter in duration
- Narcolepsy - stimulated by excitement, food, pharmacologically (rare sleeping disease)
- Pain
- Vestibular syndrome (unilateral - ataxia, nystagmus)
- movement disorder
How can you tell a mimic event to a normal seizure by treatment?
Recurrent seizures usually respond well to antiepiletic drugs
How can seizures be classified by aetiology?
- Symptomatic or secondary seizure (structural brain lesion)
- Reactive seizure (metabolic or toxic seizure)
- Idiopathic or primary epilepsy (genetic)
- Possible symptomatic/cryptogenic seizure (head trauma years previously) (only rule out at PME)
Which two types of seizures would be classified as intra-cranial?
Functional (idiopathic epilepsy) and Structural (symptomatic epilepsy)
Which two types of seizures would be classified as extra-cranial?
Intrinsic - metabolic -reactive seizures
Extrinsic - toxic - reactive seizures
What are the three types of issues leading to extracranial seizures?
- Electrolyte imbalance - hypernatraemia, hyponatraemia, hypocalcaemia
- Energy deprivation - Thiamine deficiency, hypoglycaemia
- Organ dysfunction - Uraemic encephalopathy, hepatic encephalopathy
What are some examples of intracranial symptomatic epilepsy?
- Anomalous- hydrocephalus, lissencephaly, archanoid cyst
- Neoplasia- meningioma
- Infectious- viral, fungal, bacterial, parasitic, protozoal
- Inflamm
- Traumatic
- Vascular- haemorrhagic (secondary to hypertension and coagulopathy, ischaemic)
What is the average age range for dogs to get seizures?
<6 months to 6 years
What are likely reasons for seizures at
a) 6 years
a) Metabolic (portosystemic shunt, hypoglycaemia), infectious diseases
Congenital
b) Idiopathic epilepsy, inflammatory/infectious, metabolic
c) Neoplasia, idiopathic epilepsy (late onset), inflammatory/infectious
What diagnostics would you use for extra-cranial problems?
- Complete blood count + cytology
- Biochemistry
- Resting bile acids
- Urinalysis
- Blood pressure (in cats)
What diagnostics would you use for intra-cranial problems?
- Imaging - MRI and CT
- Cerebrospinal fluid analysis (WBC)
