Seizures - Part I Flashcards
Seizure - definition
_____ brain dysfunction due to excessive ______ neuronal discharge
Seizure is a ____, not a disease
Paroxysmal
Hypersynchronous
SIGN
Seizure Pathophys
Anything that alters electrophysiology, can precipitate seizure activity
- NT involvement (GABA, Glutamate, etc)
- Receptor dysfunction (GABA, NMDA, etc)
- Ion channelopathies ( Cl, K, Na, Ca, etc)
- Ion imbalances ( Ca, Mg, Na, etc)
Epilepsy definition
______ seizures caused by any intracranial cause
Recurrent
Primary/idiopathic epilepsy
- no identifiable pathologic cause
- may or may not be inherited
- Dx of exclusion
Familial Epilepsy
- subtype of primary epilepsy
- inherited basis
- occurs in families
Secondary/Symptomatic Epilepsy
- Epilepsy due to a structural brain lesion
tumor, vascular/stroke, others
Cryptogenic Epilepsy
- Epilepsy due to a probable brain lesion, but cant be identified definitively
- Probably Symptomatic Epilepsy
- Lesion not apparent on imaging
Reactive Epilepsy
- epilepsy due to the following causes:
metabolic, toxic, infectious, or inflammatory - brain may return to normal once treated
Period of time prior to seizure activity
Prodrome
Initial manifestation of seizure (EEG activity)
Lasts mins to hours
Aura
Actual seizure event
Lasts seconds to minutes (avg 90 sec)
Ictus
Follows the seizure event
Lasts mins to hrs; occasionally days
Post-ictal period
Generalized tonic-clonic seizure
aka ‘grand-mal’
Appearance:
- symmetric throughout body
- tonic phase (rigid extension)
- clonic phase (paddling, running)
- chewing, facial movements, autonomic signs
*typical form of idiopathic epileptic seizures
(Generalized) Absence seizure
“Petit mal”
Appearance:
- NOT a focal/partial seizure
- sudden, brief loss of consciousness
- sudden, brief loss of mm tone
- different drug therapy than other seizure types
- not yet recognized ini dogs
(Generalized) Myoclonic Seizure
Appearance:
- sudden mm contraction or “jerking” movement
- symmetric throughout body
- consciousness is lost; but episode is so brief the loss may go unnoticed
- may be triggered by stimuli of any type
Partial/focal seizures
- Usually assoc’d with secondary epilepsy
- occasionally idiopathic or familial epilepsies
- area of body affected reflects location of seizure focus
- motor cortex = contralateral limb/facial movements
- occipital cortex = fly-biting, visually triggered behaviors
- limbic system = abnormal behavior episodes
- autonomic signs may also occur
Simple partial seizure
Appearance:
- focal motor activity
- conscious awareness is MAINTAINED
- unilateral facial twitching, head turn, or repetitive limb movements
- autonomic signs may be present
- seizure focus is in contralateral motor cortex
Complex partial seizure
Appearance:
- focal motor activity
- conscious awareness is IMPAIRED
- unilateral facial twitching, head turn, or repetitive limb movements
- autonomic signs may be present
In cats, bizarre behavior may be present (hissing, growling, running)
- seizure focus in contralateral temporal lobe
Psychomotor seizure
Appearance:
- conscious awareness is IMPAIRED
- abnormal sensory, behavioral activity (rage, hysteria, hallucinations, fly-biting)
- seizure focus thought to be in limbic system, but may reflect occipital cortex involvement
Single isolated seizure which ceases spontaneously
Self-limiting
- two or more seizures in a 24 hr period
- usually requires intervention
- may lead to status epilepticus
Cluster
- single seizure >5mins
- > 3 seizures without return to normal consciousness
- motor activity may dissociate from brain activity
- true emergency
Status epilepticus
*Severe metabolic complications if untreated!!
If death occurs, usually from:
- cardiac arrhythmia
- non-cardiogenic pulmonary edema
- renal failure
Difficulty performing a movement
Dyskinesia
- due to other involuntary movements
- encompassess all active movement phenomena that are attributed to the basal nuclei
Seizure = ___ origin
Dyskinesias = _____ and _____
cortical origin
Basal nuclei and muscle membrane disorder
Normal vs abnormal tremors
Normal (physiologic)
- enhanced physiologic tremor
Abnormal (pathologic)
- tremors that impeded normal movement
Clinical Decisions
< 6 months
- anomalous/congenital cause (hydroencephalus, congenital metabolic - PSS, hypoglycemia)
- toxins
- infectious etiologies
- breed related encephalitides
- idiopathic is possible, but less likely
Clinical Decisions
6 mo-5 years
- idiopathic/inherited is most common!!
- symptomatic, reactive causes are possible
- rec minimum database
- +/- advanced diagnostics
Clinical Decisions
> 5 years
- secondary (symptomatic) and cryptogenic causes are most likely
- rec full workup (advanced imaging, CSF)
- precede workup for min database, met screen
Clinical Decisions
Breed predispositions
- many breed predisposed to epilepsy
- labs, GSD, Goldens, Beagles, Cocker Span, Poodles
- many toy breeds predisposed to inflammatory encephalitides (yorkies, maltese, pug, chihuahua)
