Seizures Flashcards
What are the seizure criteria and how many must the episode match to be considered a seizure?
- Hypersalivation, urination and/or defecation - PS signs
- Tonic/tonic-clonic movements or rhythmic contractions of facial or appendicular muscles
- Altered mentation or decr responsiveness
- Postictal period - abnormal behavior or mental state noted; blind, frantic, ataxia, dullness
What are things that could causes a seizure-like episode?
- Narcolepsy/cataplexy, REM sleep movement disorders
- Syncope
- cardiac dz
- hypoglycemia
- myoclonus
- anemia
- e- abnormalities
- Atlanto-axial luxation
- COMS
- vestibular events
- head bobbing
Define a seizure. What are some possible causes of a a seizure?
Hypersynchronous electrical activity causing abnormal and excessive discharge of neurons in the brain
- Decr inhibition (GABA, glycine)
- incr excitation (glutamate, aspartate)
- high estrogen levels/low progesterone
Why is spaying an epileptic patient often indicated?
Because estrogen decreases seizure threshold and progesterone enhances GABA and inhibits glutamate
What are the phases of seizures?
Pre-ictal: may be a partial seizure
Ictal: seizure
Post-ictal: confused, absent menace
What is the difference between cluster seizures and status epillepticus?
Cluster - more than 1 seizure in 24 hours
Status epillepticus - longer than 5-20 min or not normal b/t events
What is epilepsy and what are the 4 etiologies?
Epilepsy = more than 1 seizure
Etiologies:
- Familial/idiopathic/primary: presumed genetic 1-4 yrs
- Symptomatic/Secondary - known underlying cause (neoplasia, infection, inflammation)
- Reactive
- Cryptogenic - suspect cause though not identified
What is a generalized seizure?
Focus in one cortex that reaches thalamus and disseminated throughout the brain
What is the difference between a simple and complex focal seizure?
Simple - consciousness unimpaired
Complex - consciousness impaired: fear, anger, behavioral abnormality, autonomic, “psychomotor”
What is a simple partial seizure?
Disturbance of motor function only, no loss of responsiveness
What is a complex partial seizure?
Disruption of the sensorium +/- motor (fly biting/flank chewing), decreased responsiveness
What are your initial diagnostics for a seizure work-up?
Hx, exam findings, MDB, rads, abd U/S, fundic exam, endocrine status, hepatic function, current anti-convulsants levels
What are three advanced diagnostics you can use for a seizure workup?
Advanced imaging - CT vs. MRI (gold standard)
Electroencephalogram (EEG)
CSF analysis - infectious dz titers
What are diseases that could cause seizures that follow the DAMNITV scheme?
Congenital - hydrocephalus
Metabolic
Neoplasia - primary vs. metastatic
Infectious/Inflammatory - viral, protozoal, fungal, MUE, GME, NME
Vascular event - stroke vs. hemorrhage
Epilepsy - familial vs. cryptogenic
What are metabolic causes for seizures?
- Hypo- or hyperglycemia
- DM, insulinoma
- Electrolyte disturbances (Na, Ca, Mg)
- Renal failure
- Hepatic dz/failure - PSS
- Toxins
What types of neoplasia can cause seizures?
Primary - meningioma, glioma, lymphoma, insulinoma
Secondary Metastatic - lymphoma, hemangiosarc
What are inflammatory/infectious causes of seizures?
Autoimmune, MUE, GME, NME, infectious: tick borne dz, protozoal (Toxo, Neospora), fungal (crypto, blasts, aspergillus), viral (rabies, distemper)
What are some vascular events that can cause seizures?
Ischemic/stroke, hemorrhagic, underlying endocrine disorders, underlying infectious dz
What are the causes of seizures in cats?
- Epilepsy
- thiamine deficiency
- infectious (cuterebra, crypto, FIP, FIV, Toxo)
- Hypertensive encephalopathy (CRF, hyperthyroid)
- Meningioma, LSA
- PSS in kittens
- Vascular
What are important factors that play a role in quality of life when managing epilepsy?
Underlying cause, seizure freq and severity, owner compliance, stress associated w/ seizure event, stigma assoc w/ certain AEDs
What are goals of therapy for management of epilepsy?
Decr frequency, decr severity, and good quality of life
What are AEDs that block Na channels?
Phenytoin, Valproate, Topiramate
What are AEDs that block Ca channels?
Topiramate, Gabapentin/Pregabalin
What AEDs enhance GABA?
Benzos, barbiturates
What AED inhibits glutamate?
Topiramate
What are the most common anticonvulsants?
Phenobarbital, KBr, Levetiracetam (Keppra), Zonisamide, Pregabalin (Lyrica)
Describe phenobarbital
MOA: incr neuronal responsiveness to GABA, anti-glutamate, decr Ca flow into neurons
Half-life: 40-90 hours
Ideal b/w 25-35 mcg/ml and monitor q 6mo
What are some side effects of phenobarb?
PU/PD/PP
hepatotoxicity (esp. when blood >35mcg/ml)
auto-inducer of cP450
sedation/ataxia
Describe KBr
MOA: traverse neuronal Cl channel and hyperpolarize neuronal membrane to cause an incr seizure threshold
Half-life: 28d, steady state @ 4 mo
Excreted via kidneys
What are some side effects of KBr?
Coughing (pneumonitis in cats) - DO NOT USE IN CATS
Pancreatitis - may develop elevated triglycerides
vomiting
Describe Levetiracetam
MOA: inhibit voltage-gated Ca channel, neuro protective
Half-life: 3 hours
Given PO TID to QID
What are the side effects of Levetiracetam?
Few to no side effects - transient sedation
Describe Zonisamide
MOA: block T-type Ca and voltage gated Na channels, bind to Cl channels associated with GABA
Half-life: 15 hours in dogs
What are the side effects of Zonisamide?
Ataxia, lethargy, KCS, vomiting, polyarthropathy, suppression of thyroid hormone synthesis, hepatotoxicity, renal tubular acidosis, calcium oxalate urolithiasis
Describe Gabapentin
MOA: structural analog to GABA and enhances action, inhibit voltage gated Na/Ca channels
Half-life: 3- 4hrs
*Terrible anticonvulsant, great for pain
Describe pregabalin (lyrica)
MOA: Gabapentin analog - decr Ca influx resulting in decr glutamate and substance P
Half-life: 7hrs
Expensive human product
don’t routinely monitor drug levels
What are principles for monitoring AED use in epileptic patients?
- Use a single agent to its maximal effect before adding or switching to another AED
- monitor levels for phenobarb, KBr, and Zonisamide
- monitor side effects
What are some alternative treatments for epilepsy?
Vagal nerve stimulators - internal and external
Ketogenic diet - not easy in dogs
Food allergies - novel protein or reduced antigen food?
What are the effects of status epilepticus?
Results in neuronal cell death from excitotoxicity from glutamate and influx of Ca through NMDA glutamate receptors
What are the goals of emergency management therapy for seizures?
- Stop seizures!
- support systemic function
- protect brain function
- assess underlying cause
What are your emergency management medications options for seizures?
Bolus diazepam (IV or per rectum)
midazolam (IV or intranasal)
AED loading dose (Phenobarb, KBr)
CRIs of prop, midazolam, dexmed, Levetiracetam
Which disease is which?
