Neuro Flashcards
Which 2 clinical signs can be expected with neuromuscular disease?
Weakness
Exercise intolerance
What are the systems that can cause weakness?
- Cardiovascular and respiratory (ie. arrhythmia, hypotension, hypoxemia…)
- Systemic/ Metabolic (i.e sepsis, electrolyte imbalance such as hypocalcemia, hypoglycemia..)
Weakness can be 2 things
1) focal
2) generalised (may involve CNs leading to signs such as dyphagia, dysphonia, regurgitation..)
What clinical signs may be seen with weakness?
- difficulty getting up
- short strides
- stiff gait
- plantigrade stance
On Physical exam, what signs may you see that makes you think of signs of weakness?
- muscle hypertrophy
- muscle atrophy
- myalgia (muscle pain)
- ventroflexion in cats
What do postural reaction tests assess?
Proprioception
If a patient has a spinal cord injury, would the postural reactions be affected?
If the lesion is cranial to the limb segment- then yes.
If a patient has neuromuscular weakness, what would the postural reactions be like?
Intact, can be reduced. The animal is weak but knows where its limbs are (it is only the motor unit that is affected)
In neuromuscular disease, are the spinal reflexes increased or decreased?
Typically decreased (especially if neuropathy)
If all spinal reflexes are reduced and reduced tone in all limbs- what is the most likely explanation and the least likely?
- Most likely: generalised myopathy, neuropathy or junctionopathy
- Least likely: Spinal cord lesion in C6-T2 and L4-S3
What happens to muscles in a neuromuscular disorder? (LMN loss)
Atrophy
Common cause of ventroflexion in the cat
hypokalaemia
Common cause of eclampsia in the bitch?
hypocalcemia
What is ‘reflex fatigue’?
If you repeat reflex again and again it will eventually stop occurring i.e. Palpebral reflex. This mimics exercise tolerance (i.e Myasthenia Gravis)
Ventroflexion in a cat- is it a neuropathy? a junctionopathy? or a myopathy?
Myopathy
You have a patient with really flaccid limbs, decreased spinal reflexes and a plantigrade stance- Is it more likely to be a neuropathy, junctionopathy or myopathy?
neuropathy
You have patient with weakness, myalgia, exercise intolerance and normal spinal reflexes- neuropathy? a junctionopathy? or a myopathy?
myopathy
80% of dogs with acquired Myasthenia Gravis will have…
Megaesophagus
Megaesophagus predisposes to …?
aspiration pneumonia
What diagnostic tests can we do to test for myopathy?
Look at muscles enzymes: CK, AST, ALT enzymes.
Urinalysis: myoglobinuria
What test can be used to differentiate between muscle disuse due to orthopedic problems Vs myopathy/neuropathy?
electromyogram
What test helps us differentiate between neuropathy, junctionopathy or a myopathy
nerve conduction test
Acute Canine Polyradiculoneuritis is cause by?
Immune mediated inflammatory disease affecting the ventral nerve root
If a dog has miosis, ptosis and facial paralysis - is it peripheral or central vestibular disease?
peripheral
If a cat seems obtunded and has a horizontal strabismus that can change direction- is it peripheral or central vestibular disease?
central
Central vestibular disease includes what structures?
the vestibular nuclei
the cerebellum
the cerebral cortex
Peripheral vestibular disease includes which structures?
the hair cells
the vestibulocochlear nerve
the ampulae cristalis
the maculae
Could a peripheral lesion causing vestibular disease also lead to facial paralysis?
Yes
Could a peripheral lesion causing vestibular disease also lead to Horner’s syndrome?
Yes
What is this and how do you treat it?
SCCED or ‘indulent ulcer’ or ‘boxer ulcer’
Ulcerative disease
treatment: only ulcer that can be debrided (cotton bud, diamond burr or keratectomy)
What is this? What is the risk?
A foreign body.
Ulcerative disease
It can migrate and damage the lens.
What is this? How do you treat it?
This is a melting ulcer caused my Pseudomonas.
Ulcerative disease
Fluroquinolones required. This is an emergency do not wait!
What is this? How do you treat it?
This is a perforation filled with a fibrin plug.
Ulcerative disease
Do not remove the fibrin plug. Requires surgical treatment.
What does this represent?
a desmetocoele.
Ulcerative disease.
Pattern caused by uneven fluorescein staining
What is this?
Corneal oedema due to endothelial disease.
What is this? What are the causes? Treatment?
Mineral deposits in the cornea
Non ulcerative
Can be there for lots of different reasons :
- Old age
- Chronic irritation
- Hereditary
Can also occur with some systemic disease i.e. hypothyroidism, diabetes, lipid deposits- you need to treat the systemic underlying cause
What is this? Treatment?
Pigmentary keratitis is found in almost in every brachycephalic pug. It can progress to the degree where it becomes blinding. So important to monitor the progression
What is this?
Acute Bullous Keratopathy.
Non ulcerative
Very rare
Patients present suddenly with extreme corneal oedema
What causes this?
Feline Herpes
Non ulcerative
What is this?
Chronic superficial keratitis (Pannus)
Caused by UV damage
Treatment is cyclosporin and corticosteroids
What is this?
Eosinophilic keratitis
Full of eosinophils
Non ulcerative disease
Treat with cyclosporin and corticosteroids
What is this?
Keratoconjunctivitis Sicca (Dry eye)
Ulcerative disease
What is this?
Deep ulcer
Ulcerative disease
When the ulcer becomes deeper than 50 % then we need to provide some mechanical support to prevent it from this also from rupturing.
What is this?
Corneal sequestrum
Non ulcerative disease
necrotic part of the cornea
Would need to be removed
Causes of corneal edema
endothelial degeneration
uveitis
lens luxation
glaucoma
What are the 4 medical management treatments for corneal opacity
- anti-collagenase
- antibiotics
- mydriatic cyclopegics
- anti-inflammatories/ immunosupressives
How long does it take for the epithelium
1 - 2 hours
If deeper layers of the epithelium are lost how long may it take to repair?
a week if the limbus stem cells are still intact.
How long do vessels take to grow per day in the process of corneal healing?
0.5mm per day
How long does it take for the stroma to heal?
weeks to months
How long does it take for the endothelium to grow?
Unfortunately the endothelium is only one cell thick and is non-regenerative.
What features can be seen with progressive retinal atrophy (PRA) when examining the fundus?
- hyperreflective tapetum
- vascular attenuation
- end stage: catarracts
What can cause retinal toxicity in cats?
enrofloxacin
What causes symblepharon in cats?
FHV1
What is this?
pigmentary keratopathy
What is this? What does it need to be differentiated from?
synechia
Needs to be differentiated from persistent pupillary membranes (PPM)
What is this?
Hypopyon
7 causes of cataracts
- congenital
- inherited
- nutritional
- traumatic
- metabolic
- PRA
- senile
What are the clinical signs of uveitis?
- hypopyon
- hyphaema
- aqueous humour flare (tyndall effect)
Uveitis is a local or systemic problem?
Both
local: a trauma, corneal ulcer
systemic: pyometra, urinary tract infection, hyphaema could be due to coagulopathies
What is the pathophysiology of glaucoma?
Aqueous humous is produced by the ciliary body, flows through the pupil and should exits in the drainage angle. There is a problem of outflow leading to increased IOP and optic nerve damage.
What are the signs of acute glaucoma?
- corneal oedema
- episcleral congestion
- hyperemia
What does this show?
Persistent pupillary membranes
These can extend from
either iris to iris, iris to
lens or iris to cornea.
What is this?
iris atrophy
can occur with age.
The pupil margin
ragged; this can appear
as mydriasis if the pupil
margin is not examined
closely
What does this represent?
an iris coloboma.
Developmental defect leaving a hole is this iris at 6 o clock
What does this represent?
Iris melanoma- can be benign melanosis or
a neoplastic change for
example iris melanoma
What is this?
a uveal cyst.
Spherical cysts formed
from the uveal
epithelium, these are
usually free floating in
the anterior chamber,
however can also burst
and leave pigment on
the corneal endothelium
What is this?
anterior lens luxation. anterior displacement of the lens means the pupil cannot constrict and dilate as normal.
What is SARDs?
Sudden acquired retinal degeneration syndrome.
Acute blindness - idiopathic
What does the fundus of a SARDs dog look like?
Normal
When doing an electroretinogram for a SARDs patient what may you expect?
a flat line
What is this?
optic nerve neurits
This is an inflammation of
the optic nerve and
manifests as blindness or
if very early reduced
vision. The optic nerve
head is pink/
haemorrhagic, swollen
and there can be
peripapillary oedema/
retinal detachment.
Cataracts can lead to glaucoma. How?
cataracts—> uveitis—> pre-iridal fibrovascular membranes (PIFM)—> synechia—> glaucoma
uveitis can cause miosis or mydriasis?
Miosis
Horner’s syndrome can be defined by what 4 characteristics?
Miosis,
enophthalmos, third
eyelid protrusion and
ptosis (drooping of the
upper eyelid)
Glaucoma- miosis or mydriasis?
Mydriasis
Dysautonomia- miosis or mydriasis?
mydriasis
Means dysregulation of the autonomic system.
Fear- miosis or mydriasis?
Mydriasis-
When animals are very
stressed, they have a
heightened sympathetic
stimulation and thus
mydriasis that is usually
not very responsive to
bright light and therefore
a reduced or absent PLR
In a chiasmal lesion would the pupils be constricted or dilated? PLR absent or present?
dilated-
Nothing works!
In a re-chiasmal lesion (right) what would the PLR direct and indirect be in each eye?
In an oculomotor nerve lesion (left) what would the PLR direct and indirect be in each eye?
Parasympathetic nucleus of CN3 lesion (right)
With SARDs what would the menace response and PLR be?
No menace response, absent or decreased PLR
Enophthalmia define
retraction of the bulb within the orbital cavity known as
enophthalmia. Due to ocular pain, reduced amount of
retrobulbar fat, periocular/facial muscle atrophy (typical of
elderly cats, weight loss, long-term use of steroids)
