Seizures Flashcards by Emma Mortensen

Define seizure

Clinical manifestation of excessive hypersynchronous neuronal activity

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What causes seizures?

Inadequate neuronal inhibition (GABA and glycine)
Excessive neuronal excitation (aspartate and glutamate)
Both

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Define epilepsy

Enduring disorder of the brain characterized by recurrent seizures (symptom, not a dz)

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Define cluster

2 or more seizures within 24h

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Define status epilepticus

Seizure lasting longer than 5 min or 2 or more seizures without recovery to consciousness

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Define refractory/pharmacoresistant epilepsy

Failure to achieve freedom from seizures despite adequate trials of two or more well-tolerated AED regimens

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Define generalized (grand mal) seizure

Bilateral involvement and loss of consciousness
Salivation, urination and or defecation
Typically less than 3 min
Presents as:
- Tonic
- Clonic
- Tonic-clonic
- Myoclonic
- Atonic
Focal
Focal with secondary generalization

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Define generalized focal or partial seizure

Ictal onset consistent from one seizure to another
Electrical activity arises from opposite hemisphere
Difficult to assess consciousness in patients (not recommended anymore)
Lateralized and/or regional signs
- Motor
- Autonomic
- Behavioral

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Three components of seizure

Preictal
Ictal
Post ictal

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Prodome/preictal

Prior to onset of seizure
- Hours to days
- Should not be confused with focal seizure signs
Clients may not report this
- Confusion, hiding, attention seeking, etc

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Ictus

May be generalized, focal, or focal to generalized
Lasts seconds to minutes
- Duration of seizure measured during this period only

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Post ictal

After seizure
Can last minutes to days
Behavior changes and neuro symptoms may be seen (may be only sign of seizure)

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Etiology based classification

Idiopathic or structural

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Idiopathic epilepsy subtypes

Genetic (incomplete penetrance of several genes)
Suspected genetic
Unknown cause

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Idiopathic epilepsy basics

Common neuro dz
- Affects 1-5% of entire dog population
- About 3 mill ppl in USA
Refractory in about 25% of cases
- Canine is excellent animal model

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Breeds commonly affected by idiopathic epilepsy

Australian shepherd, border collie, goldens, collies
Arabian foals
Aberdeen Angus, Brown Swiss, Swedish Red

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Testing for idiopathic epilepsy

None yet
Dx of exclusion

Factors supportive of dx:

Seizures between 1-5y
Normal interictal period
Normal dx testing

Idiopathic epilepsy of unknown cause

Classification of seizures where the cause is not determined but genetic epilepsy is unlikely

Dx testing normal
Signalment

Idiopathic/Unknown epilepsy in cats

Unknown versus presumptive unknown

- Subtypes

Structural epilepsy

Epileptic seizures dt brain activity

Degenerative
Anomalous
Metabolic
Neoplastic
Inflammatory
Traumatic
Vascular

Diseases confirmed by diagnostic testing
- MRI, CSF, biopsy/necropsy, DNA testing

Seizure like episodes

Syncope
Vestibular
Narcolepsy, cataplexy, REM sleep disorder
Cervical muscle spasm/ AA luxation
Head bobbing
Feline hyperaesthetic syndrome
Panic attack
Intermittent decerebrate rigidity
Neuromyotonia or neurokymia
Toxicity

What are the three questions for all seizure cases?

Is it a seizure?
What is the cause?
Does it require Tx?

Is it a seizure?

Start with Hx

Ask open ended questions
Specifically describe what happened before, during, and after event
How long did it last?
Abnormalities during interictal period?

Ask client to video episode

Performing a neuro exam

Look for evidence of other cerebral or thalamic abnormalitis

Blindness, decreased menace response
Circling, proprioceptive deficits
Hemi-inattention syndrome
Behavior changes

Diagnostic tests

Electroencephalogram (EEG) MRI CSF analysis Infectious disease titers, metabolic screening tests

How does one decide when to start tx?

``` Consider the disease - Tx any underlying issue causing symptom of a seizure Consider seizures - Kindling phenomenon Consider pt (quality of life, etc) ```

T/F: treatment is often started after 1 seizure

False; no benefit

T/F: the earlier a treatment is started, the better the potential for seizure control

True

T/F: Prolonged or repetitive seizures can increase morbidity, mortality, and require prolonged hospitalizaiton

True; increases financial burden

When is seizure treatment required?

Identifiable structural lesion present or prior history of brain disease or injury Acute repetitive seizures or status epilepticus - Ictal event >5min or 3 or more generalized seizures within 24h period Two or more isolated events within a 6 month period Prolonged, severe or unusual post ictal events

Client communicaiton

Seizure control - Target is 50% reduction in seizures or more - Decrease frequency, duration, and intensity Unrealistic that there will be no seizure Pt may require lifelong tx Frequent reevaluations and monitoring Do not judge efficacy of medication until reaches steady state Potential for ER visits Possible drug side effects DO NOT change medication doses

Which drug should be used first?

Based on tolerability in pt

Efficacy of monotherapy anticonvulsants

Phenobarbital: 60-80% of dogs Bromide: 70-80% Zonisamide and levitiracetam - Excellent based on experience (lack of research) - Less side effects than phenobarbital and bromide

Efficacy in Polytherapy

``` Phenobarb: 70-80% Bromide: 65% Zonisamide: 58-90% Levetiracetam: 57-97% Pregabalin: 7/9 Gabapentin: 50% ```

Recommendation for owners

At home, after a seizure - Give extra dose of anticonvulsant after pt is awake and aware to swallow - Exception is bromide Owner should record every seizure - Date, time, duration of each phase

Monitoring therapeutic blood levels

After steady state reached after starting Tx, changing dose, or immediately after loading - Provides baseline Seizures are not controlled - Helps determine if dose change or additional medication is needed Signs of possible dose related toxicity Every 6-12 months to verify no changes in pharmacokinetics - Variable usefulness

Recommendations for monitoring

CBC chem in all pts every 6 mo Phenobarbital and bromide levels - After reaching steady state - Every 6 mo

Recommendation for owners

Pt that tend to cluster - Consider pulse dose of short acting drug over 48h period - Levitiracetam and gabapentin work well, if the pt is not already on these meds for maintenance AVOID ER

Emergency Tx

``` Seizures lasting longer than 5 min 3 or more seizures within 24h ABCs Get vital parameters IV access ```

Emergency drug therapy

``` Levetiracetam Benzodiazepams (add something else on board) - Diazepam - Lorazepam - Midazolam ``` If no IV access: keppra SQ or IM Diazepam rectally Midazolam IM

Emergency seizure management

Run bloodwork to eval for hypoglycemia, renal, or hepatic dz Collect blood for levels before loading - In pt on AED therapy - Without serum separator for Pb

T/F: Propofol CRI is controversial in seizure pts

True; will stop motor activity but not seizure; use inhalant anesthesia