Epileptic seizures Flashcards
When in the day do seizures occur more often and why?
At night as the brain is less active and has less inputs from sensory organs
Define a seizure
Hypersynchronicity of neuron firing where all nerves fire at the same time
Transient and involuntary change in behaviour or neurological status due to the abnormal activity of populations of CNS neurons
How are seizures named?
By clinical signs
How are seizures treated?
Increase inhibition not to decrease excitation as a way to do this hasn’t been discovered yet
What are the different methods of classifying seizures?
By clinical signs
By duration/timing of seizure
By aetiology
How are focal seizures classified?
Simple focal = no loss of consciousness
Complex focal = impairment of consciousness
Focal seizure with secondary generalisation
And then also by sensory/motor/autonomous
How are generalised seizures classified?
Convulsive - further by type of convulsion
Non-convulsive
Define status epilepticus
Prolonged seizure activity which requires treatment if longer than five minutes as at this point it becomes a clinical case
What happens when a seizure lasts a long time?
If its longer than 30 minutes then it results in brain damage
The longer a seizure lasts the more difficult they are to treat
Define cluster seizures
More than 2 seizures in a 24 hour time period
What do cluster seizures indicate?
That it is a serious case that is likely to be more difficult to treat
What are the four stages of a seizure?
Prodrome = behavioural changes that occur hours/days before Aura = sensory/focal onset seizures start with a sensory experience such as a perceived smell/feeling of deja vu Ictus = seizure onset Post-ictal = neurological status alterations hours or days after the seizure
What types of seizures can be focal and self-limiting?
Sensory
Motor
Automatisms (orofacial/chewing gum)
What types of generalised seizure can be self-limiting?
Tonic-clonic
Clonic
Myoclonic
Atonic
What types of focal seizure can be clustered or continuous?
Epilepsia partialis continua = motor
Aura continua = sensory and difficult to classify in dogs
Which types of generalised seizure can be clustered or continuous?
All of them
What are reflexive seizures?
Seizures that have a precipitating stimulus
What events can mimic seizures?
Syncope, narcolepsy, pain (esp cervical), vestibular syndrome, movement disorders
What are the features of a tonic-clonic seizure?
Tonic phase 1st where all the muscles tense
Clonic phase follows which is seen as the limbs jerking rapidly and rhythmically
What is the appearance of a clonic seizure?
Repeated jerking movements of limbs caused by rapidly alternating contraction and relaxation of muscles
What do myoclonic seizures look like?
Brief shock like jerks of a muscle/group of muscles
What do atonic seizures look like?
Abrupt loss of muscle tone resulting in a drop to the floor
How can seizures be classified by aetiology?
-> Functional -> Idiopathic epiliepsy
-> Intracranial -> Structural -> (possible) Symptomatic
Seizures
-> Extra-cranial -> Intrinsic (metabolic -> Reactive
-> Extrinsic (toxic) -> Reactive
What are some differential diagnoses of extra-cranial seizures?
Electrolyte imbalances (hyper/hyponatraemia, hypocalcaemia) Energy deprivation due to thiamine deficiency or hypoglycaemia Organ dysfunction such as uraemic encephalopathy (kidneys) or hepatic encephalopathy (liver)
What are some differential diagnoses of intra-cranial seizures?
Cryptogenic epilepsy (head trauma from years ago with normal imaging) Symptomatic epilepsy
What are the DDx for symptomatic epilepsy?
Anomalous (hydrocephalus/lissencephaly/arachnid cyst)
Neoplastic (meningioma/ependyoma/choroid plexus tumour/astrocytoma/oligodendroglioma)
Infectious or inflammatory ( various meningio-encephalomyelitis)
Traumatic
Vascular (ischaemic or haemorrhagic secondary to hypertension)
What are the characteristics of idiopathic epiliepsy?
Ion channel genetic mutation or other genetic abnormality
Found in dogs aged 6 months to 6 years
Generalised seizures or partial seizures depending on breed
What breeds are affected by generalised idiopathic epilepsy?
Beagles, GSD, Labradors, Golden Retrievers, Bermese Mountain Dogs, Belgian Terwerens, Keeshounds, Irish Wolfhounds
What breeds are affected by partial idiopathic epilepsy?
Vislas, English Springer Spaniels, Danish Labradors, Lagotlo Romagnolo, Standard Poodles and Finnish Spitz
How can signalment help refine the problem list?
< 6 months = metabolic, infectious, congenital, toxic, trauma
6 months - 6 years = idiopathic, inflammatory/infectious, metabolic, neoplastic, toxic, traumatic
> 6 years = neoplastic, idiopathic late onset, inflammatory/infectious, metabolic, toxic, trauma
How do you define disease onset and progression?
DAMNITV
Degenerative, anomalous, metabolic, neoplastic, inflammatory/infectios, trauma/toxic, vascular
How do inter-ictal neuro-exam findings narrow down the problem list?
Normal = idiopathic, metabolic, neoplastic, toxic
Abnormal symmetrical = metabolic, toxic, hydrocephalus, degenerative, midline structural
Abnormal asymmetrical = neoplastic, inflammatory/infectious, anomalies
What does a minimum data base include?
CBC and cytology, Biochemistry, Ammonia, Resting bile acids, Urinalysis, Blood pressure in mature animals
What additional diagnostic methods can be used?
Imaging using MRI/CT
CSF analysis for WBC, differential cell count, protein content
Positive brain imaging/inflammatory CSF
