Exam 2 - Seizures Flashcards
what is the most common neurological problem in small animal medicine?
seizures
what is a seizure?
hypersynchronous electrical activity of cortical neurons
defects that alter a group of neurons - potential for marked & prolonged depolarization
what are the major inhibitory neurotransmitters?
GABA & glycine
what are the major excitatory neurotransmitters?
aspartate & glutamate
what are the two general causes of seizures that occur in combination?
inadequate neuronal inhibition & excessive neuronal excitation
what is epilepsy?
disease characterized by an enduring predisposition to generate epileptic seizures & by the neurobiological, cognitive, psychological, & social consequences of this condition
______ is the event, while ______ is the disease
seizure
epilepsy
what is another name for the pre-ictal phase?
prodome
what are clinical signs of an animal in the pre-ictal phase?
abnormal behavior - may be clingy or may go and hide
what is ictus?
the seizure it self
what is seen during the ictal phase?
tonic/clonic seizures, non-responsive, urinating, defecating, & salivating
how long does the post-ictal phase last?
minutes to days
what clinical signs are seen in an animal during the post-ictal phase?
disorientation, blindness, & ataxia
T/F: the longer the seizure, the longer the post-ictal period
true
what is the general definition of a tonic-clonic seizure?
animal gets stiff (tonic)
then progresses to paddling (clonus)
what is clonus?
repetitive/rhythmic activity
before a generalized seizure in a dog, how may an owner describe the clinical signs?
dog chokes & turns blue
tonic - muscles of respiration get stiff
what does a generalized seizure look like?
class tonic-clonic activity
animal gets stiff & progresses to paddling
what parts of the CNS are affected in generalized seizures? why is this important?
both sides of the brain are affected, so the animal will have diffuse general movement & disorientation
how will an animal respond to an outside stimulus during a generalized seizure?
they won’t be responsive
T/F: during a generalized seizure, the animal may vomit, urinate, or defecate on themselves
true
T/F: any dog breed can get partial or focal seizures
true
while clinical signs are variable in partial/focal seizures, what may they include?
fly biting, ‘seeing ghosts,’ leg pulling, & head turn prior to generalized seizures
what are partial/focal seizures often secondary to?
CNS insult or genetically determined
T/F: partial/focal seizures come from one or more foci, & can spread to involve entire brain
true
what is status epilepticus?
seizure that lasts longer than 5 minutes or 2 seizures without a complete recovery in between
why is status epilepticus considered a medical emergency?
can lead to brain damage - hypoxia & hyperthermia
can lead to organ failure - multi-system failure, DIC, etc.
what is the number one differential for seizures?
syncope
how can you diagnose syncope?
put an ecg on the patient
what is idiopathic head-bobbing?
same direction head-bobbing every time with breed predilection for bulldogs, dobermans, & boxers
regardless of underlying cause, what are the 3 goals of seizure therapy?
- decrease number of seizures
- decrease severity of seizures
- increase the normal interictal period
regardless of underlying cause, what are the goals of acute seizure therapy?
stop the seizure & look for underlying cause - check bloodwork & look at BG
what are some examples for seizure-like events that are differentials for seizures?
narcolepsy, vestibular disease, myasthenia gravis, cerebellar tremors, neck spasms, & behavioral problems
what is the mechanism of action of benzodiazepines in seizure control?
lipid soluble drug that enters the brain rapidly
binds to GABA receptors, enhances neuronal hyperpolarization which leads to reduced neuronal activity
how long does an intermittent bolus of a benzodiazepine last?
approximately 30 minutes
what is the easy math for giving diazepam (valium) in a seizing animal?
0.5mg/kg at 5mg/ml given IV
move the decimal point over one spot
25kg dog gets 2.5 ml
10kg dog gets 1 ml
what dose can you give of diazepam if the animal is also on phenobarbital?
2mg/kg given rectally
T/F: IN midazolam works faster than IV valium
true
what is the goal of maintenance seizure therapy?
aimed at controlling seizures not curing them
-goal of no seizures with minimal side effects
-issue can become quality of life
under what conditions should maintenance seizure be started?
-when an animal has 2 or more seizures within a 6 month period
-seizures are increasing in frequency, severity, & duration
-status epilepticus or clusters
-severe post-ictal signs
-suspicion of structural lesion based on neuro exam
why is client education so important in maintenance therapy in seizure patients?
owner compliance is key!!!
risks in stopping drugs abruptly or altering doses on their own & keeping a seizure log
when selecting a drug for seizures, what is the definition of effective?
for an FDA approved drug to be considered effective - there must be a 50% reduction in seizure frequency
what drugs are apart of the 1st generation AEDs?
phenobarbital
KBr
benzodiazepines
how is phenobarbital metabolized?
through the liver
what is the success rate of phenobarbital?
60-80% effective in idiopathic epilepsy patients
what 1st generation AED has a high incidence of side effects?
phenobarbital
if you are giving phenobarbital, you expect ALP to become high, but why would you be concerned if both ALT/ALP become increased?
concerned about hepatotoxicity!!!
what is the dosing for phenobarbital?
2-3mg/kg BID
what are the common side effects seen with phenobarbital?
liver problems, PU/PD/PP, inducible enzymes, autoinduction can shorten drug half-life, sedation, & ataxia
what is the rare dermatological side effect associated with phenobarbital?
superficial necrolytic dermatitis
what are some rare side effects of phenobarbital?
neutropenia, anemia, & thrombocytopenia
what drug is the first choice for cats in many cases for seizure control? why?
phenobarbital
fewer side effects seen in general & don’t appear to develop metabolic tolerance from autoinduction enzyme
what was the first AED used in people?
potassium bromide
T/F: potassium bromide is effective as sole therapy drug or an add-on
true
how is potassium bromide metabolized in the body?
through the kidney
what is the time to reach steady state for potassium bromide?
3 months
what is the dosing used for potassium bromide?
20-30mg/kg/day
what seizure drug can not be used in cats & will kill them?
potassium bromide
how long can sedation last as a side effect from potassium bromide?
up to 3 weeks
why should you not use potassium bromide in cats?
increased risk of pneumonitis
how can you avoid gi side effects of potassium bromide?
start with dosing 2x a day
what are the common side effects of potassium bromide?
PU/PD, sedation, ataxia, pancreatitis, & vomiting
what are the 2nd generation AEDs?
zonisamide & levetiracetam
what is the time to steady state for zonisamide?
3 days
how is zonisamide metabolized?
mixed liver & kidney
what are the side effects of zonisamide?
sedation, ataxia, rare gi signs, reports of hepatic disease, & reports of renal tubular acidosis
what is the dosing used for zonisamide?
twice daily dosing
what is the time to steady state for levetiracetam?
within 1 day
what are the side effects seen with levetiracetam?
mild sedation, transient decreased appetite
what is the dosing used for levetiracetam?
20mg/kg - every 8 hours!!! critical owner compliance
how is levetiracetam excreted?
unchanged through the kidneys
T/F: levetiracetam is effective in cats for seizures
true
what is the downside of using levetiracetam?
TID dosing - much more difficult for owner compliance
due to the half life of the drug, dosing needs to be every 8 hours
what is keppra XR?
long-acting formulation of keppra
what is the dosing of keppra XR?
30mg/kg BID
T/F: once daily dosing of keppra XR may be effective in some dogs
true
what is the limiting factor of keppra XR? why?
size of the patient
can’t cut the tablets in 1/2 because the coating of the pill is what makes it extended release
T/F: animals on keppra XR may pass whole pills in their feces
true
what is pulse therapy used for?
effective at breaking the seizure cycle but not the current seizure - will prevent more from happening
what drugs can be used for pulse therapy? how can this help owners?
chlorazepate - always oral
benzodiazepines
owners can have medication on hand at home
what is the dosing used for pulse therapy?
TID day 1 (1mg/kg)
BID day 2
once a day on day 3
what drugs are your 1st line AEDs?
phenobarbital
KBr
zonisamide
keppra
what AED has the longest time until steady state?
KBr
what is the time to steady state for phenobarbital?
2 weeks
what is the cheapest AED?
KBr
how should KBR be monitored?
check levels every 3 months or if there is a change in seizure control
how are levels of zonisamide & keppra monitored?
not done as often - check if poor seizure control and if there are significant side effects
how are levels of phenobarbital monitored?
2 weeks, 3-6 months, & yearly - must also check bile acids
or if there is a change in seizure control
how should seizure drugs be monitored?
CBC, chemistry panel, & electrolytes - 2 weeks, 1 to 3 months, 6 months, & yearly
