Seizures Flashcards
What is epilepsy?
Disease condition characterized by recurrent portion or generalized seizures
What are the two forms of epilepsy ?
Primary (idiopathic)—>no known cause
Secondary(symptomatic)—> has discernible intra- or extra- cranial cause
T/F: partial/focal seizures are most indicative of symptomatic epilepsy
True
-usually from post-trauma, space-occupying lesions, or cortical developmental disorders
What type of partial seizures are most common?
Partial motor seizures, caused by a lesion in the motor cortex
What signs do you see in a partial motor seizure?
Brief episodes of abnormal movment in the contralateral body part
- jerking of one or both limbs
- chewing gum fits
- flexing to one side of body
- head turning
- head bobbing
T/F: head bobbing in a partial seizure starts and stops spontaneously but can be stopped by distracting the dog
True
What signs can you see in a partial seizure that causes abnormal behavior?
Aggression or rage
Excessive salivation
Licking or chewing
Sudden voracious consumption o food/water
Uncontrolled running/vocalizing/trembling
What is a characteristic sign of absent seizures ?
Brief loss of consciousness that appear to be “staring into space” or “blanking out”
Can be associated with loss of muscle tone or muscle twitches
A partial sensory seizure is due to a lesion where?
In the sensory cortex
What signs would you see in a dog with partial sensory seizures?
“Fly-biting” or “Tail chasing”
T/F: partial seizures may become generalized seizures
True
What is a generalized seizure?
Abnormal activity over the entire cortex —> widespread activation of the brain
What are the forms of generalized seizures?
Generalized tonic-clonic seizure Tonic seizure Clonic seizure Atonic seizure Absence seizure Incomplete
What is an atonic seizure?
Loss of muscular activity but consciousness is maintained
What are the phases of a generalized tonic-clonic seizure?
Preictal phase - minutes (aura) or hours (prodromal) before convulsion
Ictal period -actual seizure with loss of consciousness
—> tonic phase - widespread muscle contraction
—> clonic phase -alternating contraction and relaxation of muscles
Postictal phase -gradual return to consciousness
Limbs extended rigidly
Opisthotonos
Apnea and cyanosis
What phase of a seizure is this?
Tonic phase
Animal appears to be running or paddling and chewing
Can have salivation, deification, and urination
What phase of a seizure is this?
Clonic
Animal with varying degrees of depression, fatigue, fright, dazed appearance, aimlessness, pacing, thirst or hunger
What phase of a seizure is this??
Postictal period
Occasionally can have neurological deficits such as blindness, paresis, or in coordination
T/F: cluster seizures are seizures that are separated by minutes to hours where the animal returns to full consciousness in between episodes
True
_____________ is where there is continuous seizure activity for more than 5 minutes and the animal does not return to full consciousness between episodes
Status epilepticus
How can you differentiate between seizures during sleep and excessive sleep movement??
Attempt to wake animal
—> excessive sleep movement, animal wakes normally with no pot-ictal signs (confusion/ataxia)
What is the difference in treatment for primary/idiopathic vs secondary epilepsy ?
Primary-> anticonvulsant drugs
Secondary-> treat underlying disease
In general practice, ___________ is the most important cause of provoked seizures
Toxicity
When do seizures usually develop in cats and dogs with idiopathic epilepsy
1-5years
What would your differential list be for young animals with seizures?
Primary/idiopathic
Toxicity
Congenital abnormalities
Infectious disease
What would be your differential list for older animals with seizures ?
Neoplastic
Systemic metabolic disease
What breeds commonly have seizures?
Golden retrievers German shepherds Border collies Poodles Shelties Welsh corgis Cocker spaniels
T/F: the older the animal is when seizures start, the more severe the epilepsy is likely to be and the more difficult it will be to treat
False
the YOUNGER the animal is when seizures start, the more severe the epilepsy is likely to be and the more difficult it will be to treat
Episodic weakness can appear like seizures to owners, what are causes of episodic weakness?
Syncope Narcolepsy, Scotty cramp, episodic falling Sudden onset of vestibular disease Hypoglycemia Hyperkalemia Hypocalcemia Cardiovascular disease Myasthenia gravis Polymyositis
What information in a history would suggest a seizure?
Neurological abnormalities
—> changes in personality and behavior, circling, unilateral proprioceptive defects
What would be important aspects of a physical exam to rule-in/out seizures?
Cardiovascular abnormalities —> syncope secondary to hypoxia
Neoplasm —> metastases
Systemic infection —> distemper or FIP
Abnormalities in skull —> trauma, hydrocephalus
Retinal exam—> active/healed rential lesions (toxo/FIP/distemper)
When you do a neurological exam, localized lesions are suggestive of what DDX?
Primary tumors
Focal inflammation
Infarction
Brain trauma
When doing a neurological exam and lesions appear to be multifocal, what is your DDX?
Secondary neoplasia
Infectious disease
Degenerative disease
Metabolic disease
Why use an EEG in seizure diagnosis?
Can confirm diagnosis and discriminate between general and partial seizures
Can help identify a suspected seizure focus
What are indications for starting an animal on anticonvulsant drug therapy?
Frequency and severity..
- seizures more than once every6-8weeks
- clusters of seizures (several in a day)
- prolonged seizures than might cause neuronal damage
- status epilepticus
- symptomatic epilepsy caused by CNS disease
Only _________% of animals will be free of seizures on anticonvulsant therapy, and only _____% will have a reduction in the number of their seizures?
30-40; 50
—> therapy is generally lifelong
When can withdrawal of seizure medication be considered?
If animal has been seizure free for more than one year..
withdrawal is gradual over 6-12months
Sudden discontinuation can result in severe seizures
Remission rate only 15%
Antiseizure drugs often have long half lives, what implications does this have on monitoring and dosages?
Loading doses should be given for animals with severe seizures
Blood levels should be taken when
- steady state levels have been reached or after loading dose
- if seizure is not controlled
- dose related toxicity signs
- when autoinduciton occurs
- every 6-12months
What is the drug of choice for treating seizures and what is its MOA?
Phenobarbital
enhance GABA action —> elevate seizure threshold
When is use of phenobarbital contraindicated?
Liver disease
What are the adverse effects of phenobarbital ?
Sedation and ataxia - usually disappear in the first few weeks
PP/PU/PD
Liver enzyme induction
Lipidemia —> predispose to pancreatitis
What laboratory abnormalities would you see on a patient treated with phenobarbital ?
Increase ALP and ALT
Due to enzyme induction, cannot asses hepatotoxicity with these values
Because of phenobarbital’s effect on liver enzymes, how must you dose it over time?
Phenobarbital is an enzyme inducer—> enhances its own metabolism —> must gradually increase dose over time (autoindution may continue for up to 6 months)
What are signs of liver failure, what can help you determine if liver failure is present on lab work of a patient that is on phenobarbital ?
Sedation, ataxia, anorexia, jaundice, acities, and encephalopathy
Increase in bile acids and bilirubin
Proportionally large increase in ALT over ALP
Can see increased phenobarbital levels —> lack of metabolism in liver (causes the ataxia and sedation)
T/F: hepatotoxicity caused by phenobarbital is reversible if drug is withdrawn early in disese
True
-> this is why we do 6-12months bloodwork
T/F: dogs on phenobarbital will have similar clinical and laboratory signs to dogs with hyperadrenocortisim
True
—> adrenal function tests are normal
You initiate treatment with phenobarbital, what is your follow up procedure?
Measure [PB] for the first time a 3weeks and adjust dose accordingly
Remeasure at 6weeks and then at 3 and 6 months after —> detecting liver enz induction
CBC at 3 or 6 weeks —> detect idiosyncratic blood cell disturbances
Long term—> [PB], liver function, and CBC every 6-12months
T/F: Doses of phenobarbital are much smaller in puppies than adults
False
Puppies have increased doses (up to 50%) because they have increased distribution volume/clearance, and decreased half-life
What is the MOA of bromide??
Moves through Cl- channels and hyperpolarizes membranes
—> mimic inhibitory affect of GABA making depolarization more difficult
When is bromide used?
As refractory drug to phenobarbital
-can help control up to 70% of seizures that are not controlled by phenobarbital
For patients on bromide therapy, how should diet be changed?
Low salt / consistent salt intake diet
—> chloride competes with bromide for reabsorption, with high levels of chloride, bromide excretion increases and concentration falls
—> low salt intake —> decreased excretion and a rise in bromide concentration
Can bromide be given to dogs with renal insufficiency?
Yes but should only receive 50% of the recommended dose and be monitored very closely
How can you treat dogs with bromism toxicity?
Given high chloride diet/furosemide to hasten excretion
What are adverse effects of bromide?
PP/PU/PD
Personality change- Irritability, attention seeking, and aimless pacing
Sedation for first few weeks of therapy is common
T/F: unlike phenobarbital, bromide does not cause changes in ALP, ALT, or thyroid levels and is not hepatotoxic
True
When is bromide contraindicated?
Renal insufficiency
Cats —> feline asthma or renal insufficiency
Refractory epilepsy occurs in 10-20% of dogs despite appropriate treatment with phenobarbital and bromide. What treatment methods can you use in these patients?
Phenytoin - short half life
Primidone - only about as useful of phenobarbital and expensive
Benzodiazepines - short halflife and rapid tolerance (5-7days)
Imepitoin - partial benzodiazepines agonsit (GABA) about as effective as PB
What are side effects of imepitoin?
PP/PU/PD Hyperactivity Apathy/Somnolence Hypersalivation Emesis /diarrhea Ataxia Decreased sight and sensitivity to sound
—> usually not severe and only temporary
T/F: blood monitoring of imepitoin is not required
True
There is no correlation between dose and reduction in seizure frequency
What drug has been shown to reduce seizures when given as a “pulse treatment” when pre-ictal signs occurred?
Levetricetam (Keppra)
What are common reasons for inadequate decrease in seizure frequency and or seizure severity ??
Owner non-compliance Incorrect dosage of anti epileptic drug Failure to monitor drug levels Generic factors Incorrect diagnosis Wrong drug Concurrent disease (liver/kidney) Tolerance to drug Monotherapy is insufficient Hepatic enzyme induction
What are non-drug therapies for seizures?
Surgery (resect focus or separate corpus callosum) Vagus nerve stimulation Acupuncture Ketogenic diets Hypoallergenic diets
What is juvenile epilepsy??
Generalized tonic-clonic seizures that begin in clinically normal puppies up to 4 months of age, often littermates
Phenobarbital is often effective and prognosis is good once seizures are under control and puppies develop into normal dogs, not requiring treatment
About ___% of cats have non-convulsive seizures that are mild, generalized seizures/ partial seizures/ complex focal seizures
50
T/F: symptomatic epilepsy is more common in cats than it is in dogs
True
About 50% of epilepsy cases in cats is symptomatic, only about 20% in dogs
What are common diagnostics run in cats with seizures?
CBC Chem profile Bile acids Serum T4 FeLV/FIV testing
What is a feline audio genie reflex seizures??
Focal or generalized seizures in response to high-pitched sounds, like crinkling tin foil, or metal spoon, tapping glass
How are Feline audiogenic reflex seizures controlled?
Levetricetam (70%) better than with phenobarbital (25%)
When should anticonvulsant therapy be started in cats?
Seizures becoming more frequent
Status epilepticus / clusters
Seizures more often than every 12weeks
What is the drug of choice for treatment of seizures in cats?
Phenobarbital
-contraindicated in liver disease
T/F: diazepam can be used to treat seizures in cats
True
However contraindicated in.. liver disease, oral can cause hepatotoxicity
T/F: imepitoin is well tolerated by cats and can prevent seizures
True
What can cause status epilepticus ??
Cerebral trauma Intracranial space occupying lesions CNS infections Acute metabolic disturbances Idiopathic epilepsy
What changes occur in the body during the early stages of status epilepticus ?
Autoregulatory mechanisms in the brain increase blood flow to meet metabolic demand for oxygen or glucose
Vasodilation and increased blood flow to muscles to correct hypoglycemia, hyperkalemia, and lactacidosis.
Increased cardiac output by SNS
What occurs in the body if status epilepticus is maintain longer than 30mins?
Cardiac output is no longer sufficient to provide for metabolic demands of tissue
—> metabolic acidosis, hypoxia, hypercapnia, hypoglycemia, hyperpyrexia, electrolyte disturbances, myoglobinuria, renal failure, respiratory failure, and arrhythmias
—> ischemia and neuronal cell death
What is the treatment of status epilepticus?
First, stop seizures.. then maintain..
Airway, oxygen IV line Temperature Glucose ECG Blood gases and pH
How can you stop a status epilepticus seizure when the animal is convulsing?
Diazepam- IV bolus/rectally/intranasally
Lorazepam -IV(longer acting)/IM/ intranasally
Midazolam -IM/ intranasally
When seizing has decreased, place IV line and administer another bolus of diazepam if seizure has not completely stopped
Being maintenance phenobarbital
If the animal is not longer seizing on presentation from a status epilepticus seizure, how would you treat?
Sample for lab analysis
Administer phenobarbital loading dose
What do you do if seizures cannot be controlled with diazepam or phenobarbital ?
Induce general anesthesia with IV pentobarbital
Propofol can be used to induce anesthesia and maintained CRI
What supportive therapy should accompany treatment of status epilepticus once seizures are under control?
Brain edema —> mannitol/ dexamethasone/methylprednisone succinate
Treat any lab abnormalities —> glucose/calcium
Body temp—> cooling
Turn stuporous animals to avoid lung congestion and clean to avoid dermatitis, eye lubricaiton, express bladder, fluid therapy
