Final: Neuro Flashcards
What distinguishes a pathologic nystagmus from normal nystagmus?
Pathologic if occurs in absence of head movement
How do we assess smell in horses?
If they are eating they can smell
What is the best way to assess vision?
Obstacle course/ Maze
Can blindfold one eye and then the other if suspect unilateral vision problems
Which nerves are most commonly affected when there are vision problems? Of these which is most comon?
V, VII, VIII
VII (Because it is superficially located)
What nerve is affected if the masseter is atrophied? What does it mean if the jaw is dropped?
CN V
Bilateral nerve damage
What horse-specific signs are associated with Horner’s?
Asymmetric nasal airflow (localized congestion)
Unilateral sweating on neck
(Also abnormal position of eyelashes)
When CN VII is damaged on the right, to which side does the muzzle deviate?
To the normal side (left)
When CN VIII is damaged, in which direction is the head tilt? To which side do they lean and fall?
Toward lesion
To affected side
The fast phase of nystagmus is _____ the lesion.
Away from
What does Dog Sitting imply?
Neurologic disease of some kind, often the case that it is more severe in the hind limbs
R/O Weakness since +++ weight in hind
If you notice a horse being as affected or more affected in the forelimb than the hind limbs what lesion comes to mind?
Low cervical (C6-7) lesion or cranial intumnescence involvement
In order to evaluate gait a grading system is used. How many grades are there? Which three parameters are used IN EACH LIMB for evaluation and what grades are used for these?
6 grades (0 - 5) 5 is most severe- recumbent
Weakness
Spasticity
Ataxia
Graded 0 to 4+
When you grade the gait and posture and note that only weakness and spasticity are abnormal (i.e. no ataxia) what does this indicate?
Weakness or lameness rather than neurologic disease
What words are used to describe weakness when assessing gait and posture?
“ings”
Toe dragging
Knuckling
Buckling
Stumbling
What can cause toe dragging?
Mechanical disruption (tendon rupture, DJD…)
Weakness
What are the 2 causes for spasticity?
Hypermetria: excessive joint flexion
Hypometria: short choppy gait, ‘tin soldier’ gait
What does it indicate if a horse vacillates it’s leg in the air before setting it down?
Ataxia
What signs in addition to ataxia and head pressing do you expect to see with cerebral disease? What other conditions cause similar sypmtoms?
Mentation and behavior abnormalities
Circling
Seizures, semi-coma, coma, death
Other conditions: Sodium imbalance, Liver disease, Moldy corn poisoning (leukoencephalomalacia- corn looks pink to brown), trauma
Does lack of a fever rule out infectious causes for cerebral disease?
Nope
What does a bacterial CNS infection do to the glucose in the CSF?
Decreases
What are the 2 locations for CSF sampling? Where should a sample be taken if you have a C2 lesion?
Atlantooccipital space
Lumbosacral space
C2 lesion= Lumbosarcal (must consider flow of CSF, it has to ‘flow’ past the lesion for the fluid to be diagnostic for the lesion)
Which type of CSF tap must be done under anesthesia?
Atlantooccipital
What is the normal TP in CSF? WBC? RBC? Color?
TP <100 mg/dl
WBC <5-6/microL
RBC none
Correction factor (blood contamination)= 1 WBC for every 500 RBC
Clear
You obtain a CSF tap and the values are:
WBC= 13
RBC= 5000
What is the corrected WBC value?
3
- 5000/500= 10*
- 13 WBC - 10 WBC = 3 WBC = WNL*
What to platelets in a CSF sample indicate?
Contamination (iatrogenic)
Or very recent (<8hrs) true hemorrhage
What test is used to determine whether antibodies are being made in the CNS?
Comparson of serum and CSF:
Albumin quotient (status of BBB, if elevated disrupted)
IgG index (if increased indicated AB production in CNS)
Antibody index (for antigen-specific antibodies)
What are your top DDx for a horse with hypersensitivity, hyperesthesia, muzzle fasciculation, and twitching? What in the CSF indicates one over the other?
West Nile Virus
Rabies
If there are neutrophils in the CSF think rabies (other viruses there will be lymphocytes and plasmacytes)
What is the most common form of rabies in horses?
Paralytic
Others are dumb and furious
How can an ante-mortem diagnosis of rabies be made?
Tactile Hair IFA
However many false negatives depending on what phase of rabies the horse is in when the sample is taken
What forms of equine viral encephalitides are most severe in horses?
EEE
VEE
For which viral encephalitides are horses amplifiers?
VEE
Sentinel/dead end host for WEE and EEE
How long are vaccines for equine viral encephalitides good for?
6 months
(also for West Nile)
Do horses always get neurologic disease associated with WNV infection?
No
If they do they get it about 8 days after infection
What is the most common presenting complaint in a horse with WNV?
Ataxia
What does it indicate if a horse with a basisphenoid fracture gets massive hermorrhage coming from the guttural pouch and inner ear? Where is is the hemorrhage going that you cannot see?
The Basilar artery and venous sinuses have been lacerated
Calvarium
What is the early treatment protocol for basilar fractures?
IV DMSO (to diminish CNS edema)
Methylprednisone (controversial)
Mannitol is counterindicated if there is active bleeding, which is common with trauma
Why should whole body sling systems not be used in horses that cannot hold themselves in a standing position?
Can cause evisceration (prolapse intestines through anus)
What decreases the prognosis in a horse with a traumatic brain injury?
Recumbence for >4 hours after injury
Basilar fracture (rather than a frontal fracture)
Respiratory symptoms (breathing alterations)
Arrhythmias
Which of these is included in the routine evaluation of a spinal ataxia case?
a. Antantooccipital CSF tap
b. CSF culture
c. LS CSF tap
d. LS spinal rads
e. Blood chemistry
c. LS CSF tap
In the gait evaluation of the neurologic horse, which of the following is an indicator of weakness?
a. Toe dragging
b. High stepping gait
c. Tin-soldier gait
d. Non-linear footfall pattern
a. Toe dragging
- B and C are indicative of spasticity*
- D is indicative of ataxia*
Does a head tilt in the abscence of blindfolding indicate acute or chronic disease?
Acute
What disease should be considered in every neuro case regardless of presentation?
EPM
What do you use to localize a lesion to the brainstem? What is most commonly affected?
Cranial nerves
CN V, VIII, and X (5, 8, 10)
What is the pathophysiology of vestibular disease due to otitis media/interna aka Temporohyoid osteoarthropathy (THO)?
Aseptic inflammatory process that is created by an extension from the ear to the joint of the temporohyoid aparatus
This results in DJD and then causes a petrous temporal fracture
This causes acute neurologic disease (usually perpheral but can be central)
What are risk factors for petrous temporal fracture?
Eating ahrd feeds (corn)
Loud vocalization (e.g. Stallion cat-calling a mare)
Yawning
What is the best way to diagnose a petrous temporal fracture? What will you see?
Endoscopy
Remodeling of the stylohyoid bone (indicating DJD)
Alternative: Nuclear scintigraphy (also might be able to see fracture on rads)
What is paradoxical vestibular disease?
Head signs indicate one side as involved while ataxia indicates the lesion is on the other side
What is the most common sign of cerebellar dysfunction?
Intention tremor
Which of the following characterized the normal value for CSF protein?
a. <50 mg/dl
b. >100mg/dl
c. <100mg/dl
c. <100mg/dl
A horse with its forelimbs more involved than its hindlimbs in terms of neurological signs probably has a lesion where?
Low cervical (C6-7)
Which of the following are included in the routine evaluation of a spinal ataxia case?
a. Physical exam
b. Neuro exam
c. AO CSF tap
d. CSF cytology
e. LS CSF tap
f. Cervical spine rads
g. Cervical spine myelogram
h. Thoracic spine rads
a. Physical exam
b. Neuro exam
d. CSF cytology
e. LS CSF tap
f. Cervical spine rads
* Note: In an adult horse you can only image the cervical spine (so myelograms are also limited to the cervical spine)*
* Myelogram would be indicated to proove a cervical spinal problem*
If you are looking at a spinal rad and all 3 vertebrae you see look the same, what vertebrae are they?
C3, C4, C5
What is the arrow indicating? What is the star indicating?
Arrow= Ski jump (remodeling of the ventral canal (dip) + caudal epiphyseal flare (upward sweep))
Star= Dorsal articular facet enlargement
How is the intravertebral saggital ratio calculated? What are the normal values for C3-C6 and for C7?
a/b x100 = saggital ratio %
C3-C6 >52%
C7 >56%
How can you differentiate a lame horse from a neurologic horse?
Lame horse will have a consistent and repeated gait abnormality
A neuro horses gait abnormality is always changing
What vertebrae is this?
C6
(Lateral process is wide and flat creating a straight line on a rad)
What vertebrae is this? How can you tell?
C2
Caudo-dorsal aspect sweeps downward and all subsequent ones sweep upward
Also characteristic dorsal spinous process?
Is muscle atrophy associated with LMN or UMN disease?
LMN
T/F: A horse presenting with CVI/CVM/CSS (Wobbler) would not manifest brain/head signs.
True
Radiographs are used to determine whether _______ is a possible cause of ataxia, a Western Blott Test is used to determine whether ____ is the cause.
Wobbler’s
EPM
What are the 6 ddx for ataxia?
EPM
EDM
Wobbler’s
EHV
Verminous encephalomyelitis
West Nile Virus
What are the 3 things that indicate EPM in a neuro case?
The 3 A’s
Asymmetric Ataxia with Atrophy
Multifocal disease
What indicates that herpes is the cause of ataxia in a horse with neuro disease? How do you treat?
Weakness (urine dribbling, symmetric signs, ascending paresis/paralysis)
Corticosteroids
Acylovir
Dietary vitamin E (and/or selenium), especially in utero and during the first year of life, plays an important role in the development of which neuro disease? When do they typically show clinical signs?
EDM
6mo - 1 year (if earlier then worse)
Supplementing RRR vitamin E helps if <1.5yrs
A lack of brain signs and hyporeflexia of the cutaneous trunci muscles indicates what disease?
EDM
In young horses cervical stenotic myelopathy tends to be _____ while in olders it tends to be _____.
Dynamic
Static
A small focal area of atrophy in a young horse that per the owner is clumsy makes you think of what disease? What may you see on a myelogram?
Wobbler’s/ Cervical stenotic myelopathy (type 1)
Ventral and dorsal attenuation of the dye column (50% attenuation compared to in front and behind)
How can you diagnose and treat a foal <1 year with Wobbler’s?
Scoring system (>12 out of 35 = CSM)
Put on PACE dietary program- to reduce energy intake and slow their skeletal growth
How much improvement can you expect post-op in an adult horse with Wobbler’s whose surgery (Bagby basket) went perfectly?
Maximum 2 grade improvement
What is the difference between a CSF tap between a horse with EPM and a horse with verminous encephalomyelitis (which present VERY similarly)?
Verminous= Eosinophils
EPM= Large mononuclear cells
- Both are inflammatory and have increase in protein*
- Any time EPM is a ddx, verminous should also be on the list (even though EPM is way more likely)*
How does an EPM horse classically present?
Undiagnosible lameness (progressive)
Acute onset EPM presents with more _____ signs, while chronic shows more ____.
Brain
Ataxia
Name 2 ddx that you can eliminate if an ataxic horse has brain signs.
Wobblers (CVM/CSS)
EDM
What is the treatment for EPM?
Ponazuril
Sulfadiazine/pyrimethamine (ReBalance)
Diclazuril
Successful in about 60% of cases
Nitazoxanide is no longer available - fatal enterocolitis
What disease classically presents as rapidly developing neurologic disease with tendency to progress for ~36 hrs and then plateau?
EHV (herpes)
How do you diagnose EHV?
CSF= High protein without significant WBC changes (Albuminocytologic dissociation)
PCR (nasopharyngeal swabs)
