Neuro: Seizures and Seizure management Flashcards
Define seizure
Clinical manifestation of excessive hypersynchronous neuronal activity
(inadequate inhibition (GABA), excessive excitation (glutamate), or both)
What is a cluster seizure?
2 or more seizures within 24 hours, with return to consciousness between seizures
What is status epilepticus?
- Seizures lasting > 5 mins
- Or 2 or more seizures without recovery to consciousness between seizures
What is pharmacoresistant epilepsy?
Failure to achieve freedom of seizures despite adequate trials or 2 or more AED drugs
How are seizure types classified?
- Generalized “Grand mal”
- Focal “Petit mal”
- Focal with secondary generalization (most common)
What is the most common seizure type?
A. Generalized “Grand mal”
B. Focal “Petit mal”
C. Focal with secondary generalization
C. Focal with secondary generalization
What are the characteristics of a generalized seizure?
- Bilateral involvement and loss of consciousness
- Salivation, urination, or defecation
- Typically lasts < 3 mins
- Presents as tonic, clonic, or tonic-clonic
What are the characteristics of a focal seizure?
- Ictal onset consistent from 1 seizure to another
- Electrical activity arises from opposite hemisphere (if lesion in L hemisphere, R side affected)
- Difficult to asses consciousness
- Lateralized or regional signs
- Tonic, clonic, tonic-clonic, or atonic on 1 side
- Salivation, urination, defecation
- Behavior changes: acting like seeing/feeling something
What are the 3 components of a seizure?
- Pre ictal phase (before seizure)
- Ictal phase (during seizure)
- Post ictal phase (after seizure)
What can occur in the pre-ictal phase of a seizure?
Confusion, hiding, attention seeking, acting weird before the onset of seizure
How long does the pre-ictal phase tend to last?
minute to hours prior to seizure
How long does the post-ictal phase tend to last?
minutes to days
What can occur in the post-ictal phase of a seizure?
- Behavior changes
- Neuro symptoms
- May be the only sign a patient had a seizure
Other than factors that precipitate stress, what physiological parameter in dogs make them more at risk for seizures?
Intact females in estrus
What are the etiology based classifications of epilepsy?
- Idiopathic
- Structural
- Reactive
What dog breeds are susceptible to idiopathic epilepsy?
- Australian Shep
- Border collie
(poor treatment response)
What factors are supportive in the diagnosis of idiopathic epilepsy?
- Seizures begin between 6m-8yrs
- Normal, conscious PE between seizures
- Normal diagnostic testing
What is structural epilepsy?
- Seizures due to brain pathology (DAMNITV)
(Degenerative, Anomalous, Metabolic, Neoplastic, Inflammatory, Traumatic/Toxic, Vascular)
How can the diagnosis of structural epilepsy be achieved?
- MRI
- CSF
- Biopsy/Necropsy
- DNA testing
What etiology-based classification of seizures is refractory to treatment in 25% of cases?
Idiopathic epilepsy
List some differentials for other diseases or symptoms that look like seizure activity, but are not true seizures
- Syncope
- Vestibular disease
- Compulsive disorders/Panic attacks
- Head tremors, neck pain
- Toxicity
- Neuromuscular diseases
- Narcolepsy, catalepsy, REM sleep disorder
- Feline hyperaesthesia syndrome
When is starting anticonvulsant therapy indicated in a patient?
- Identifiable structural lesion, or prior history of brain dz or injury
- Acute repetitive seizures or status epilepticus
- 2 or more isolated events within 6 months
- Prolonged, severe or unusual post- ictal events (Ex: aggression)
What are the goals of emergency seizure treatment?
- Stop seizure
- Prevent next seizure
- Decrease frequency
- Consider pharmacodynamics of drug choice (half life, MOA, route of admin, etc)
What drugs can be used in emergency treatment for controlling seizures?
Benzos - 1st line DOC
1. Midazolam
2. Diazepam
3. Lorazepam
2nd line AEDs
4. Levetiracetam
5. Phenobarbital
Which of the following AED’s can be given intranasally to control seizures?
Midazolam
Which of the following AED’s can be given rectally to control seizures?
Diazepam
What drug can be given to patients with brain edema from epileptic episodes?
Mannitol (osmotic diuretic)
- Decreases ICP and brain edema
- Acts as a free radical scavenger
What considerations must be made prior admin of Mannitol for seizure patients?
- Warm the line and give through special filter to avoid crystallization
- Monitor electrolytes and continue IVF to avoid renal vasoconstriction
What is the most commonly used anticonvulsant used in vet med?
Phenobarbital
What is the MOA of phenobarbital?
Binds to post synaptic Cl- channel → Increased inhibitory action → Increases GABA
What blood work changes can be seen in pets on phenobarbital?
- Hypertriglyceridemia
- Non pathologic increase in liver ALP
- Low T4, high TSH
- Cytopenias (less common)
- Hepatotoxicity (less common)
What concurrent diseases in seizure patients make them less fit for management with phenobarbital?
- Liver disease patients
- Hypothyroidism (Pheno decreases T4)
What side effects are seen in patients on phenobarbital? List the common and rare effects.
Common:
1. Sedation
2. PU/PD/PP
Rare:
1. Hepatotoxicity (dogs)
2. Cytopenias
3. Superficial necrolytic dermatitis
4. Facial pruritis (cats)
What factors affect the metabolism and excretion of phenobarbital?
- Low protein diet increases elimination
- Alkalizing urine increases elimination
- Chloramphenicol, cimetidine, and ketoconazole inhibit metabolism, prolonging half life
- Increased risk of hepatotoxicity if combined w other hepatotoxic drugs
What is the MOA of KBr?
Binds to post synaptic Cl- channel → Increased inhibitory action → Increases GABA
Which of the following AED’s can only be used in dogs, not cats?
A. Phenobarbital
B. KBr
C. Levetiracetam
D. Zonisamide
B. KBr
What side effect can occur after admin of a loading dose of Bromide?
Severe obtundation, vomiting and diarrhea
How is Kbr metabolized?
Kidney (good for liver dz patients)
Which of the following takes the longest time to reach steady state, making it least effective in managing acute seizures?
A. Levetiracetum
B. Phenobarbital
C. Zonisamide
D. KBr
D. KBr
Bromide has a _______ therapeutic index
Narrow
Phenobarbital has a ________ therapeutic index
Narrow
What blood work changes can be seen in pets on Bromide?
Pseudohyperchloremia (High Cl-)
What side effects are seen in patients on Bromide? List the common and rare effects.
Common:
1. Nausea
2. Sedation
3. PU/PD/PP
4. Pancreatitis
5. Megaesophagus
6. Irreversible pneumonitis (Cats>Dogs)
Rare:
1. Coughing
2. Aggression
3. Bromidism (ataxia, sedation)
Irreversible pneumonitis is a side effect that occurs in patients on which of the following AED’s?
A. Levetiracetam
B. Phenobarbital
C. Zonisamide
D. KBr
D. KBr
How is Levetiracetam metabolized?
By the kidney (good for patients with liver dz)
Which of the following AED’s are more preferable in patients with concurrent liver disease? Select all that apply.
A. Levetiracetam
B. Phenobarbital
C. Zonisamide
D. KBr
A. Levetiracetam (1st line for liver dz)
D. KBr
What is the 1st line AED of choice for a seizuring patient with a concurrent portosystemic shunt?
Levetiracetam (1st line for liver dz)
Which of the following AED is usually given PO q TID?
Levetiracetam (short half life)
What side effects are seen in patients on Levetiracetam? List the common and rare effects.
Common:
1. Transient sedation
2. Ataxia
Rare:
1. Behavior change (aggression)
Which of the following AEDs has the potential of causing underlying aggression?
A. Levetiracetam
B. Phenobarbital
C. Zonisamide
D. KBr
A. Levetiracetam
What blood work changes can be seen in pets on Levetiracetam?
None :)
What is the MOA of Levetiracetam?
Binds to pre synaptic vesicle protein → Inhibits excitatory synapse → Inhibits glutamate release
Also prevents hypersynchronization / antikindling effect
Which of the following AEDs can have a “honeymoon effect”?
A. Levetiracetam
B. Phenobarbital
C. Zonisamide
D. KBr
A. Levetiracetam
A patient was recently started on an at home AED for seizure management. The owner called stating that they are pooping out the capsules. Which of the following can have this “ghost pill” effect?
A. Levetiracetam
B. Phenobarbital
C. Zonisamide
D. KBr
A. Levetiracetam (Extended release)
How is the dose of Levetiracetam affected when combining with phenobarbital?
Use higher dose of Levetiracetam if on phenobarbital
Which concurrent disease requires a lower dose of Levetiracetam to be used?
Kidney disease, decreases elimination
What is the MOA of zonisamide?
- Increases inhibitory synapse @ post synaptic terminal
- Inhibits excitatory activity @ pre-synaptic terminal by blocking Na+ channels
What side effects are seen in patients on Zonisamide? List the common and rare effects.
Common:
1. Transient sedation
Rare:
1. Dry eye
2. Ataxia
3. Inappetance
4. Vomiting
5. Metabolic acidosis
6. Idiosyncratic hepatotoxicity (reason for it not being a 1st line DOC)
How is the dose of Zonisamide affected when combining with phenobarbital?
Use higher dose of Zonisamide if on phenobarbital
Which of the following AED’s should not be used in a seizuring patient with concurrent hypothyroid disease?
A. Levetiracetam
B. Phenobarbital
C. Zonisamide
D. KBr
B. Phenobarbital (decreases T4)
A value > _______ when measuring phenobarbital levels in blood results in hepatotoxicity
> 35
