Neuro Flashcards
Neuro location options for ATAXIA ONLY
Cerebellar or Vestibular
Neuro location options for PARESIS ONLY
Neuromuscular Disease or Lumbo-Sacral
Neuro location options for ATAXIA AND PARESIS
Spinal cord or brainstem
5 Finger rule components:
(signalment)
Onset, clinical course, lateralization, neurological localization, pain
Main components of a neurological exam
Mentation Gait/posture Cranial Nerves Postural reactions Spinal Reflexes Palpation
Common causes of progressive neuropathy in young dogs
Immune mediated inflammation of the brain- meningoencephalitis of unknown aetiology -
Infectious diseases including bacterial infection - most commonly intracranial spread of an otitis interna, fungal cryptococcus, viral - Distemper or protozoal Neospora
Common fungal pathogen causing neuropathy in pet rabbits
Encephalitozoon cuniculi
Leads to granulomatous inflammation
Most common brain tumor encountered in cats
Meningioma
Two most common spinal diseases in cats
FIP virus myelitis
Spinal neoplasia - spinal lymphoma associated with FeLV
Both have chronic onset with progressive clinical disease usually seen in younger cats
What are the three functional divisions of the cerebellum?
Cerebrocerebellum, Spinocerebellum, & Vestibulocerebellum
In the differential diagnosis of the “wet eye” what do you consider to be the most important decision to make?
Is the wetness due to excessive lacrimation or is it an epiphora?
Basically is it increased production or decreased drainage?
What is the most common CSF finding from a canine patient with Steroid Responsive Meningitis Arteritis (SRMA)?
Neutrophilic pleiocytosis (increased cellularity with neutrophils)
What are common clinical signs of hydrocephalus?
Dome-shaped head
Behavioral changes - congenital
Open fontanel
Diverging strabismus - ventrolateral strabismus (setting sun eyes)
What is the difference between Type 1 and Type 2 (Hansen) intervertebral disc disease?
Type 1 - extrusion of the nucleus pulposus of the disc due to mineralization
Type 2 - protrusion of the annulus of the disc - usually due to hypertrophy
Describe a myelogram.
Injection of contrast into the subarachnoid space to see and analyze the spinal cord on radiographs - best used to see compressions and deviations
What is the typical patient with Type I IVDD (IVD extrusion)? Think about signalment and clinical presentation specifically
Chondrodystrophic dog breeds = Dachshunds, Basset Hounds, Beagles, Corgis, French Bulldogs. Rarely in cats
Often young to middle-aged dogs
Typically acute, more rapidly progressive, painful
What is the typical patient with Type II IVDD (IVD protrusion)? Think about signalment and clinical presentation specifically
Middle-aged or older dogs (or cats)
Often large non-chondrodystrophic breeds
Typically chronic, slowly progressive, non-painful
What would the gross spinal cord of a dog with steroid-responsive meningitis arteritis look like?
Darkened areas with hemorrhage and inflammatory lesions
Histology - Inflammatory cells will be located within the MENINGES and surround the blood vessels
** This was in 2 separate DLs so I think it’s important*
What are differential diagnoses in a horse with spinal ataxia?
Cervical vertebral malformation/stenosis Equine Herpes Virus (EHV1) Equine degenerative myeloencephalopathy Trauma Migrating parasites Equine protozoal myeloencephalitis Ryegrass staggers
Clinical signs of equine herpes virus (EHV1)?
Ascending paresis/ataxia
Pyrexia
Bladder incontinence
Tail paresis
Where does EHV1 harbor within the CNS to make it a lifelong disease?
Trigeminal ganglion
Describe what is seen with dynamic stenosis of cervical vertebral malformation type 1.
Paresis and ataxia - all 4 limbs
With neck flexion and hyperextension - the vetebrae move excessively –> cord compression
Affects C3-C5
Seen most frequently in young animals
Describe what is seen with absolute stenosis of cervical vertebral malformation type 2.
Paresis and ataxia - all 4 limbs
Osseous changes in the vertebrae that acuse spinal cord compression
Usually affects OLDER horses
Affects C5-C7
Differential diagnoses for dog with exercise intolerance and regurgitation
Myasthenia Gravis
Botulism
Hypoadrenocorticism
Polymyositis
Describe the diagnostic tests for myasthenia gravis?
- Edrophonium chloride challenge = TENSILON RESPONSE TEST -Edrophonium is short acting anticholinesterase drug that increases AcH concentration in the NMJ - If the dog has myasthenia gravis - this will show a marked imorovement in muscle strength and exercise tolerance for a few minutes
- Nicotinic acetylcholine receptor antibody serology = most specific and sensitive test for myasthenia gravis - tests for circulating antibodies against the nicotinic ACH receptors
What would be an ideal treatment plan for diagnosed myasthenia gravis?
- Supportive care - preventing aspiration pneumonia, fluids if regurgitating often, GIT drugs - prokinetics to speed up the movement of food, nutritional support - feed from a height
- Anticholinesterase drugs
- Immunosuppressive drugs
What are the main sources of infection from Clostridium Botulism?
Forage poisoning - feed material with preformed toxin - soil contamination or air got into it
Wound botulinum - anaerobic wounds contaminated by the botulinum spores
Toxico-botulinum- usually seen in young foals caused by an infection in the GIT and production of the toxin –> absorption
How does botulinum toxin cause clinical signs?
Botulinum toxin acts at the neuromuscular junction by inhibiting the release of Acetyl choline vesicles at the presynaptic membrane. Without ACh, the nerve signal is not passed to the post synaptic muscle membrane.
What are the clinical signs associated with each of the 3 main forms of grass sickness (chronic, acute, subacute)
Thought to be from an enteric Clostridium botulinum toxin
Chronic= Weight loss, dysphagia, patchy sweating, muscle fasciculations, variable tachycardia, paretic stance.
Sub-acute = Dysphagia, colic (often impactions), sweating, muscle fasciculations, tachycardia
Acute = Severe, sudden onset colic with small intestinal distension and nasogastric reflux, death by gastric rupture
What are the clinical signs of equine motor neuron disease?
Usually caused by chronic vitamin E deficiency leading to free radical damage and attack of type 1 fibers in muscles of posture/core strength "Horse on a drum" stance Low head carriage muscle fasciculations = twitches Patchy sweating
How to easily differentiate between tetanus and exertional rhabdomyolysis?
Blood sample and test for CK activity
Both botulism and tetanus are caused by clostridial toxins. So why does botulism cause a flaccid paralysis whereas tetanus causes a spastic paralysis?
Botulinum toxins work at the NMJ
Tetanus acts at the spinal cord after being tracked up from the motor neurons - they inhibit the inhibiting NTs from “renshaw cells” –> excitation
Dog comes in seizuring, what do you do?
This wasn’t on the notes, I just researched it in case it comes up in the long papers
1) Diazepam IV (if you can’t put IV cath in then give it rectally)
2) If diazepam doesn’t work give it Phenobarbitol (loading dose) or Levicetaram (might be preferred because doesn’t cause obtundation but more expensive)
3) If again this doesn’t work give propofol
IN THE MEANTIME PROVIDE O2 WITH A MASK/FLOW BY
- The dog has stopped seizuring-
5) IV Fluids (correct hypernatremia, hypocalcemia, hypoglycemia) but take blood sample first!
6) cool down if TRP> 40C
7) keep on Phenobarbitol after seizure has stopped to prevent recurrence
8) Intubate for O2 administration if patient doesn’t have a gag reflex (heavily sedated)
9) while the patient is resting elevate the head at 30 degrees (decrease intracranial pressure)
10) administer mannitol, then furosemide if suspecting increased intracranial pressure (these patients are hypertensive and bradycardic)
What are the definitions for Epilepsy, Cluster seizures and Status epilepticus?
Epilepsy= 2+ unprovoked seizures, more than 24h apart
SE= seizure activity for more than 5 min. seizures can be convulsive (tonic clonic movement) or non-convulsive (patient is unconscious)
Cluster seizure= 2+ seizures within 24h with a normal interictal period (recovery in between episodes)
What’s the drug of choice for cluster seizures?
Levitiracetam
Phases of a seizure
important to know while you take history. Owners might confuse epilepsy for syncope or something else
1) AURA (dog hypersalivating, anxious, altered sensory activity)
2) ICTAL (seizure episode. focal or generalized, symmetrical or asymmetrical)
3) POST-ICTAL (drowsy, confused, aggressive, increased drinking)
Why is it important to diagnose idiopathic epilepsy? Even if the dog has only had 1 episode?
60% of IE patients will have a status epilepticus episode in their life (dangerous!) so they should be on anti-epileptic therapy
Types of generalized seizures
Tonic - increased muscle tension-
Clonic - prolonged repetitive muscle contraction-
Myoclonic - jerky contractions-
Atonic - flaccid-
Types of epilepsy
IDIOPATHIC - patient normal in the intrictal period, no neuro deficits, metabolically normal, between 6mo and 6y of age, generalized sizures-
STRUCTURAL - these tend to be asymmetric + neuro deficits in the interictal period and present focal asymmetric seizures - structural brain lesion
REACTIVE - response to toxin or metabolic issue like HE, generalized seizure, symmetric neuro deficits in the interictal period -
Types of focal seizures
Autonomic - drooling, diarrhea..-
Sensory - aggression, vocalization, tail chasing…-
Motor
Confidence levels in diagnosing IE
Tier I: dog signalment fits, metabolic screening (including BA, T4, B12), physical and neuro exam - may have family history of IE as well
Tier II: Diagnostic imaging MRI and CSF analysis
Tier III: EEG
Events that can mimic epilepsy
- syncope
- acute vestibular syndrome
- narcolepsy
- movement disorders (hypertonicity and others)
Neurolocalization for seizures
FOREBRAIN!!
What is the therapeutic range for Phenobarb concentration in the blood? Why is it important that it stays within this range?
15-35 ug/ml
Causes hepatotoxicity and other nasty side effects like pancytopenia
What is first line epilepsy tx in a healthy dog?
What about a dog with hepatic compromise?
Phenobarb is first line in healthy patients.
Imepitoin can be used in patients with hepatic compromise but it’s not as effective as phenobarb
If a patient has severe seizures and hepatic compromise then consider doing low dose phenobarb + KBr
How many days does it take each drug to reach plasma steady state?
Why do you need to know?
Cause that’s when you need to check plasma levels of the drug in case of ineffective seizure control
Phenobarb = 14d
KBr = 120d (slow mf)
Imepitoin = 1-2 d
What mechanism is responsible for anti-epilepsy tx failure?
p-glycoprotein efflux pumps in the BBB.
These are ATP dependent pumps that pump out drugs from the brain. If the gene encoding them (MDR-1) is overexpressed -> drugs don’t work
Collies have common MDR-1 mutation -> so ivermectin and other drugs can cause CNS toxicity at lower dose
What are some considerations with KBr as antiepileptic tx?
- never a sole treatment, only add-on
- renally excreted
- put these patients on fluids-> they will start seizuring agin (because increased KBr excretion)