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Paroxysmal period of abnormal cerebral function associated with a variety of clinical manifestations; a clinical sign, not a specific disease.
Seizure
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Generalized seizure with a motor component.
convulsion
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A condition/specific disease characterized by recurrent seizures of neural (intracranial) origin.
Epilepsy
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What is "status epilepticus"?
prolonged seizure lasting more than 5 min--> MEDICAL EMERGENCY often results in death/permanent brain damage
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What are "cluster seizures"?
2 or more seizures in 24 hours
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What are the phases of a seizure?
aura (period before seizure), ictus (actual seizure), postictal (after seizure)
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What are the clinical manifestations of a seizure? (4)
partial or complete conscious impairment, changes in muscle tone and movement (especially in the face), autonomic disturbances, behavioral changes
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What are the classifications of seizures? (2)
generalized (motor, tonic, clonic), focal/partial seizure
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Describe a generalized motor seizure. (4)
aura absent, unconscious, tonic and clonic phases (usually), +/- autonomic signs (urination, defecation, salivation), usually <2 minutes
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What kind of diseases cause generalized motor seizures/ convulsions? (3)
primary epilepsy, metabolic/toxic disturbances
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Describe a focal seizure. (4)
consciousness, aura present, motor activity contralateral to affected cortex, facial involvement
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What kind of diseases cause focal seizures? (2)
structural cortical abnormalities, MAYBE some breeds primary epilepsy
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What kind of diseases can cause a focal seizure evolving into a bilateral, convulsive generalized seizure? (2)
structural cortica abnormalities, some breeds maybe primary epilepsy
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What is the most common factor that will lower the seizure threshold and induce a seizure?
stress
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What are the 2 general causes of seizures?
extracranial and intracranial
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What are extracranial causes of a seizure? (5)
toxins, [metabolic] hypoglycemia, hypocalcemia, polycythemia (cats only), uremic encephalopathy
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What are general intracranial causes of seizures? (2)
functional- idiopathic epilepsy, structural- symptomatic epilepsy
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What are structural intracranial causes of seizures? (5)
tumors, encephalitis, cortical dysplasia, post-traumatic injury, post-hypoxic injury
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What are the 3 ways to classify epilepsy?
idiopathic (genetic/primary), structural (symptomatic/secondary), unknown (symptomatic suspected but cannot be confirmed)
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When does idiopathic epilepsy generally present (first seizure)?
1-5 years (maybe can be stretched to 6 yrs)
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How do you diagnose epilepsy? (4)
signalment (predisposed breeds), history (multiple seizures- not just one), PE, neuro exam
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In what animals does idiopathic epilepsy generally occur?
large breed dogs with long noses, 1-5 years of age (brachycephalic dog or 10yo dog with seizures--> probably not epilepsy--> consider secondary/symptomatic seizures)
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Dogs less than 1 year old with seizures; what are your differentials? (6- in order from most likely to least)
poisoning, anomaly (hydrocephalus, dysplasia), metabolic, encephalitis, juvenile epilepsy (cocker spaniel), post-injury
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Dogs 1-5 years old with seizures; what are your differentials? (5- in order from most likely to least)
idiopathic epilepsy, meningoencephalitis, brain tumor, trauma, poisoning
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Dogs older than 5 years old with seizures; what are your differentials? (5- in order from most likely to least)
brain tumor, vascular/ischemic/hypoxic, encephalitis, insulinoma (hypoglycemia), idiopathic MAYBE
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Dogs post-status epilepticus can have neurologic deficits for up to __________.
2 weeks (or permanently)
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What are the key tests for assessing thalamocortical function after a seizure? (4)
mental status/behavior, menace response, nasal sensation, postural reactions (proprioception)
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If there is asymmetry in the neuro exam after a seizure, what can explain this?
structural or functional disease (rule out idiopathic epilepsy)
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If there is a normal neuro exam after a seizure, what is the likely diagnosis?
idiopathic epilepsy
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When approaching a case of a dog with seizures, what is your first step?
rule out extra-cranial causes (then look for evidence of brain disease with a neuro exam)
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When should you start antiepileptic therapy? (3 possibilities)
after second seizure within 2 months, dogs <2 years with idiopathic epilepsy, or dogs with cluster seizures [under any of these circumstances]
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Can you discontinue antiepileptic therapy?
can SLOWLY WEAN off is >1 year seizure free (if you stop txt abruptly or miss a pill, can induce status epilepticus and death)
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What is the most effective drug for epilepsy? What are some other options? (1, 5)
Phenobarbitol, Potassium/Sodium bromide, Zonisamide, Levetiraceta, Gabapentin, Pregabalin
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What is the mechanism of action of Phenobarbitol?
increases responsiveness to GABA, antiglutamate effects (glutamate is excitatory)
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What dose must you start at for phenobarbitol to be effective?
- dogs/cats- 2.5 mg/kg BID
- puppies- 5mg/kg BID
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How do you titrate the effective dose of phenobarbitol?
check serum level of drug 2 weeks after starting txt and adjust dose from there ONLY BY USING SERUM DRUG LEVEL (drug dose is useless in determine efficacy)
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What is the therapeutic and safe serum level of phenobarbitol?
20-35μg/mL (ideally, 23-30)
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What are potential side effects of phenobarbitol? (5)
sedation, PU/PD, hepatotoxicity (only if dose is too high for an extended period...monitor serum levels of drug and titrate), neutropenia/thrombocytopenia, superficial necrolytic dermatitis
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What are the most important aspects of using Potassium Bromide to treat epilepsy? (3)
patient's diet MUST REMAIN CONSTANT (no extra treats, same amount, same brand), SID, long half life therefore takes 3-4 months to reach steady state
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What is a big don't with KBR?
DON'T GIVE TO CATS... it will kill them
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How does KBr work?
hyperpolarizes neuronal membranes, making it more difficult to depolarize them and lead to seizure
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What is the ideal steady state serum conc of KBr?
150-300mg/dL
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Why does chloride in the diet directly interfere with serum concs of KBr?
KBr is a salt; the kidneys response is to retain dietary Cl- and excrete KBr
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What drug is a good option for "mild epileptics", and may work for families who can't afford blood work every 6 months (higher safety index)?
Zonisamide (sulfa derivative)
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What is the pro and con to Levetiracetam?
- pro- no liver metabolism and is ideal for patients with liver disease
- con- must be given every 8hrs
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What does an increase in serum ALT and ALP after starting phenobarbitol indicate?
does NOT indicate liver failure...it is expected
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How can you asses liver function in a patient that is being treated with Phenobarbitol?
bile acids
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What are the most common causes for treatment failures with epilepsy? (3)
low oral dose (not treating aggressively enough), failure to make necessary adjustments in serum conc, inadequate client education (ie. consistent diet essential with KBr)
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