Neurology 5 Flashcards
1
Q
What is epilepsy?
What is 1o/idiopathic epilepsy?
What is 2o/symptomatic epilepsy?
A
- Epilepsy = condition with recurrent partial or generalized seizures (vs. provoked seizures)
- Not a diagnosis; a condition (like anemia)
- Primary = unknown cause, no treatment
- Can only give anti-seizure drugs
- Secondary = intra/extracranial disease
- Some kind of pathology in the brain that is causing symptomatic epilepsy (tumor, parasites, etc.)
- Can get rid of underlying cause–>treat the seizures
2
Q
What are the 2 categories of seizures?
A
- Partial–disrupts function in area of cerebrum where they occur
- Often indicate symptomatic epilepsy
- Signs depend on area
- Partial motor seizures–episodes of abnormal movement
- Contralateral limb jerking, chewing gum fits, flexing, head turning
3
Q
Head bobbing
A
- Boxers, bulldogs, labs, etc.
- Boxers/bulldogs side to side
- Dobermans up and down
- Intermittent–starts/stops spontaneously or if distracted
- Cause?
- Focal seizure
- Basal nucleus discharge–dyskinesia
- Proprioception abnormality
- Diagnosis–clinical–N lab, MRI, CSF
- No treatment
4
Q
Partial seizures causing abnormal behavior–dogs
A
Aggressive, salivation, licking/chewing, sudden ingestion, run/vocal/trembling
5
Q
Partial sensory seizures
A
Sensory cortex
Dogs–‘fly biting,’ ‘tail chasing’
Put on phenobarb and will cease
6
Q
Generalized seizures
A
- Widespread disorder–not one area
- Animal can’t be conscious
- EEG–abnormal activity over entire cortex
- Generalied tonic-clonic “Grand mal”
- Most seizures in dogs
- Tonic seizures–tetanus; stiff
- Clonic seizures–muscles contract–>relax over and over
- Atonic seizures–loss of muscle tone but conscious
- Absence seizures–loss of consciousness but no tonic-clonic
- Incomplete–e.g. aura only
7
Q
What are the 3 phases of a typical generalized tonic seizure?
A
- Preictal phase
- Ictal phase (ictus)
- Postictal period
8
Q
What occurs during the preictal phase of generalized tonic seizures?
A
- Aura/prodromal phase
- Subtle behavior changes–clingy, anxious
- Few minutes - hour = aura
- Days = prodromal
9
Q
What occurs during the ictal phase of generalized tonic seizures?
A
- Unconsciousness (all neurons firing)–animal falls into natural recumbency
- Tonic phase
- 10-30s sustained muscle contraction–limbs rigid/extended, opisthotonos, apnea
- Looks like dog has tetanuus
- Clonic phase
- Running/paddling/chewing
- Autonomic–pupils dilate, salivation, defecation, urination
- Maybe further tonic contract–lasts 1-2 min
10
Q
What does the postictal phase of generalized tonic seizures consist of?
A
- Increased conscious, depression, fatigue, fright, pacing, thirst, hunger, neuro deficits
- Usually fairly rapid
- Animal behaves abnormally for awhile
- Lasts ~5 hours (not dependent on severity/duration)
11
Q
Clusters of seizures vs. status epilepticus
A
- Clusters = animal regains consciousness between seizures
- Can be bad; treat immediately
- Status epilepticus = animal doesn’t regain consciousness
- Finishes tonic/clonic phase, then another seizure immediately occurs
- Emergency
12
Q
How do you differentiate between sleep seizures and REM behavior disorder?
A
- Normally brain shuts off motor system during sleep–become paralyzed
- REM disorder = brain doesn’t suppress motor system during sleep
- Extensive motor activity during sleep
- Completely normal upon waking up
- Sleep seizure–animal won’t be normal when woken up
13
Q
What is the diagnostic approach for determining seizure type?
A
- Differentiate primary/secondary–treatment
- Signalment
- Idiopathic: 1-5 yrs
- Genetic basis in goldens, labs, poodles, border collie, GSD vs dobes, sight hounds
- < 1yr = toxic, congenital, infectious
- > 5yr = 35% idio, neoplasia, metabolic disease
- Idiopathic not too common in dobes
- Idiopathic: 1-5 yrs
- History
- Seizures? Signs?
- Episodic weakness? Syncopy, narcolepsy, etc.
- Seizures? Signs?
14
Q
History of neurological abnormalities indicates what?
What are the precipitating factors?
Duration/frequency–treatment?
A
- Intracranial disease
- Precipitating factors
- Hypoglycemia
- High protein meals
- Head trauma
- Estrus, vets, lawn, ace (no known factors)
- Treatment
- Need seizure diary
- Phenobarb doesn’t cure seizures–works in ~90% of dogs but only eliminates 50% (other 50% just decrease in frequency)
15
Q
When evaluating a patient for seizures, what is checked on the physical exam? Neuro exam? Specialty exams?
A
- PE
- Heart, neoplasms, systemic infection–retina, skull (trauma, hydrocephalus)
- Heart beats very fast–> doesn’t have time to fill –> CO decreases –> not enough blood to brain –> syncope
- Neuro exam–essential
- Abnormal findings–secondary
- Interpretation in post-ictal period?
- 45% with normal neuro (>5 yr) had abnormal CSF or MRI
- PPV = 80%
- NPV = 55%
- Special exam
- FBC, biochem, UA–normal with primary
- CT/MRI-scanning (esp. if suspect intracranial lesion
- Ex: 2yr doberman who presents for seizures
16
Q
What are CSF findings in dogs w/ seizures? EEG findings?
A
- CSF
- In all cases of 1o CSF is normal
- Increased protein + white cells = inflammation
- Increased protein = neoplasia
- Blood/xanthochromia
- Neoplastic cells
- EEG (electroencephalography)
- Confirm epilepsy–dd partial/generalized
- Find the focus
17
Q
What therapy is recommended for seizure patients?
A
- Old = delay–mirror foci/kindling
- Just because neurons on one side get excited/stimulated doesn’t mean the neurons on the other side will as well
- Balance toxic and side effects
- Ex: if animal only has 1 seizure per year it shouldn’t be put on daily phenobarb
- Frequency/pattern–assess pre-treatment
- 40% completely controlled
- 50% reduction in seizures
- Need seizure diary
- Worry abt animals w/ long-lasting seizures
18
Q
When do you treat an animal presenting for seizures?
A
- < 6-8 wks
- Clusters/prolonged/status epilepticus
- Untreatable CNS disease
- Owner insists
19
Q
Treatment of seizures–drug therapy
A
- Start with monotherapy, then polytherapy
- 1 drug–phenobarb
- If phenobarb alone doesn’t work add KBr (longer-lasting)
- 5.5 half-lives; loading doses–sedation
- Takes couple of weeks to become effective–give loading dose so the blood level for therapeutic effects is reached
- Blood levels needed when:
- Steady state, then q 6-12 mo
- Autoinduction
- Uncontrolled seizures
- Toxicity
- Slow withdrawal–never suddenly stop (will get very severe seizures)
20
Q
Phenobarbital and seizures
A
- Drug of choice
- Enhances GABA; increases seizure threshold
- Makes it harder for impulses to occur in the brain
- Don’t use with liver disease
- PU/PD/PP, sedation, hyperactive, hepatopathy (destroys liver w/ high dose for long time)
- Lipemia, ALP, ALT, T4–not bile acids, bili, US
- ALP/ALT useless when detecting hepatopathy–use bile acids (will be normal until hepatopathy)
- Competes w/ albumin–binds it and knocks down level of bound T4–>will look like dog has hypothyroidism
- Maintenance or loading dose IV
- Follow up
21
Q
Potassium bromide (KBr/NaBr)–seizure therapy
A
- Cl channels–dietary salt
- Add-on drug (70% respond; 20% off pheno)
- Adverse effects
- PP (25%), PU/PD, personaliy, GI upset, sedation
- Bromism–ataxia, paresis, hyporeflexia, tremors
- Pancreatitis (?)/megaesophagus (?)
- No liver/thyroid changes
- Too much bromide in system–> can increase salt in diet to compete w/ bromine and decrease blood levels
- Will show up as hyperchloric on clin path panels
22
Q
What are the contra-indications with using KBr?
A
- Renal insufficiency–check BUN, Cr, UA
- Cl will rise
- Excreted in kidney–don’t use if dog has kidney problems
- Maintenance– t1/2 3-6 wks
- Loading doses–vomiting and GI upset
- Have to give over days
- Follow ups
- 3 wks (50% therapeutic)
- 3 mo (renal)
- q 6-12 mo
23
Q
Imepetoin
A
low-affinity partial benzodiazepine agonist of the GABAA-receptor
Will most likely be used more frequently in the future
24
Q
What are the common anti-seizure drugs and which is preferred?
A
25
What are possible causes of therapeutic failures when treating seizures? Can anti-seizure drugs be withdrawn?
* Failures
* Owner compliance
* Weight
* Hepatic induction
* Phenobarb dose will need to be inc.
* Genes, wrong diagnosis--new diseases, etc.
* Drugs can be withdrawn
* Seizure-free for a year
26
What are some alternative therapies for seizure treatments?
* Surgery--focus
* Corpus callosum
* Joins hemispheres together--if severed, seizure can be localized to left side only--\> won't fall unconscious, etc.
* Vagal nerve stimulation
* Pressure on vagal nerve--\> seizure aborted
* Acupuncture
* Ketogenic diets
* Hypoallergenic diets
27
Juvenile epilepsy
* Generalized tonic-clonic seizures in clinically normal puppies up to 4 months of age
* Lab results are normal
* Good response to phenobarb
* 5 mg/kg q 12hrs--100-200µmol/L
* Wean if seizure-free after 6 mo
* Etiology? Prob. multifactorial
* **Prognosis good once seizures are controlled**
28
What breed is highly associated with juvenile epilepsy?
Lagotto Romagnolo
Very high rate of juvenile epilepsy--\> new gene assoc. w/ epilepsy
29
Seizures in cats (signs, most common type)
* Signs more variable--hyperesthesia/violent
* 50% have non-convulsive seizures (mild generalized or partial seizures, complex focal seizures)
* Idiopathic epilepsy
* Cats 1-5 yrs 50% vs 80% are primary/idiopathic
* Extensive work-up needed
* FIP, cryptococcus, thyroid, shunts, lymphosarcoma, FIV, FeLV, HCM, etc.
30
Which idiopathic epilepsy is most commonly seen? What seizures are more common in general practice?
* Intracranial pathology most common (dogs and cats)
* Reaction seizures are more common in general practice
31
Anticonvulsant therapy in cats? Phenobarb?
* Q 12 weeks (much harder to pill cats), clusters/SE, inc. frequency
* Phenobarb
* Same as in dogs
* Maintenance dose lower (2mg/kg BID)
* Steady state--10-14 d
* Polyphagia common, occasionally cytopenias, few hypersensitivities
* **No liver changes****/toxicity** and no liver enzyme induction
* Cats usually just tend to gain a little weight--\> switch to light food
32
Seizures in cats--diazepam? KBr?
Diazepam:
* **Not with liver disease**
* Maintenance oral dose--1mg/kg BID
* Monitor liver fx?
KBr:
* Better off just not using at all
* **Not with feline asthma, renal insufficiency**
* **CAT WILL DIE**
* Same as dogs, just smaller dose
* Conc. 50% at 2 weeks, 100% at 2 m
* 40% will cough--10% will die
33
Keppra--cats with seizures
Levetiracetam--7/10 responded; \>50% decrease in frequency
34
Status epilepticus
* Can get as a result of symptomatic epilepsy; can be the start of idiopathic
* Rapidly occurring convulsions--no complete recovery in between
* Prolonged seizures \> 5min
* Primary (60%) or secondary epilepsy
* **Immediate + aggressive treatment--brain damage**
35
SE protocol
* Goals
* Stop seizures (diaz/pheno/pento)
* Samples (FBC + biochem + urine)
* Stabilize
* Airway
* Oxygen
* Fluids
* BP and ECG
* Temperature
* Glucose
36
Seizure protocol: If not seizing + liver ok
* PB--slow IV loading dose--low therapeutic [PB]s
* Sedation--resolves in hours
* Diazepam for seizures within 20-30 minutes
* Get catheter in ASAP w/ diazepam (secure to avoid pulling out during seizure)
* Continue maintenance PB po after 12 hrs
* FYI--maintenance fluid:
* NOT lactated ringer's only--losing pure water as well
* Fluid must be 50% pure water (5% dextrose) and 50% LRS
37
Seizure protocol--if seizing
* DZ IV (IN, IR [IV best]) boli + catheter + blood
* Can't give IM
* Lorazepam (longer acting IM, IV, IN)
* Much easier to give during seizure--IM
* Midozolam (IM, IV, IN, IR)
* If want to use PB--slow loading dose IV
* Diazepam for seizures w/in 20-30 min--bolus or CRI diazepam 0.25-1 mg/kg/hr
* Maintenance oral therapy when animal can swallow
38
Seizure protocol: if DZ and PB don't work
* IV pentobarbital (barbiturate coma)
* Dangerous\*\*
* Go through excitable phase quite slowly--not a nice anesthetic
* 2-5 mg/kg to effect (1/2 wait 5-10 min)
* Propofol to effect and then CRI; ketamine CRI
* Inhalation anesthesia
* Keep under GA until no seizures on recovery
* DD paddling/excitement
* Nursing NB under GA--fluids, turn, temp
39
Seizures: supportive therapy
* Mannitol for brain edema--steroids?
* Correct glu/Ca levels
* Check for hyperthermia
* Turn--atelectasis/pulmonary congestion
* Clean and eye lube
* Hydration and bladder
40
Emergency home treatment for seizures
* Animals w/ cluster history or far away
* 2-3 seizures--5 (q 20 min) x 1.0 mg/kg DZ rectally
