SA Neuro Flashcards
Which diagnostic tests can you use to diagnose neuro conditions?
Blood, urine, faecal, microbiology Genetic testing CSF Imaging (US, radiographs, myelography, CT, MRI) Electrodiagnostics Muscle and nerve biopsies
What would you look for on a haematology test when diagnosing neuro disease?
Infectious and inflammatory dx
Hyperviscosity (polycythaemia)
Inclusions (lysosomal storage dx)
Thrombocytopenia
What would you look for on a biochemistry test when diagnosing neuro disease?
Liver function (bile acid stimulation test, ammonia)
Glucose and fructosamine (weakness, seizures)
Electrolytes (Na, K, Ca-weakness, seizures)
CK, AST (muscle damage)
Which endocrine tests may you run when investigating neuro disease (mainly for neuromuscular disease)?
- Thyroid dysfunction
- Adrenal dysfunction
- Insulin
Give some markers for immune-mediated diseases
- Acute phase proteins (eg C-reactive protein, good for steroid-responsive meningitis arteritis SRMA)
- Acetylcholine receptor antibodies titres (gold standard for acquired myasthenia gravis)
- Type IIM antibodies titres (gold standard for masticatory muscle myositis)
How does immune-mediated acquired myasthenia gravis work?
Forms circulating antibodies against Ach receptors
Which test would you use to diagnose myasthenia gravis?
Acetylcholine receptor Ab test= gold standard
Edrophonium test
IV administration of edrophonium chloride (often called tensilon) which is a fast-acting cholinesterase inhibitor
Can have false + and -
Give a potential problem with using the edrophonium test to diagnose myasthenia gravis
How would you resolve it?
Can cause a cholinergic crisis: bradycardia, salivation, miosis, dyspnoea, tremors
Give atropine
Which infectious diseases could cause neuro conditions in dogs?
Neospora Toxoplasma CDV (distemper) Cryptococcus Tick-borne diseases
Which infectious diseases could cause neuro conditions in cats?
FIV FeLV FIP Toxoplasma Cryptococcus
Why might you carry out metabolic urine screening?
To identify genetic diseases causing errors of metabolism
Most abnormal metabolites are concentrated in urine
Metabolic defects that produce organic acid accumulation often affect neuronal and muscle metabolism
Why should you always do a CSF analysis before doing a myelography?
The contrast material in the myelogram is irritable and will cause inflammation, which will affect the results of the CSF analysis
Where should you collect a CSF sample from relative to the lesion?
Caudal to lesion
When is a CSF analysis contraindicated?
Increased intra-cranial pressure (brain could herniate through skull)
Clotting problems (could cause bleeding into spine -> death)
Chiari-like malformations (syringomyelia)
Atlantoaxial instability or trauma
What shoud you never do when taking a CSF sample?
Aspirate
How much CSF should you take when obtaining a sample?
1ml/5kg
When taking a CSF sample, why should you use a plastic rather than glass tube?
Cells adhere to glass -> may get falsely low counts
What should you look at in a CSF analysis?
Differential cell count
Cytology
Protein
PCRs
What would you expect in a normal CSF sample?
<5 WBC/ul
No RBC
Protein <30-45mg/dl
What are the 2 places you can take a CSF sample from?
Cerebellomedullary cistern (atlanto-occipital joint) or lumbar subarachnoid space (L5-L6)
What position should a dog be when you take a CSF sample?
Lateral recumbency
Head 90 degrees, nose parallel to table
Where would you take a cervical CSF sample?
Imaginary line between occipital protuberance and wings of atlas (cerebellomedullary cystern)
Where would you take a lumbar CSF sample?
L5-L6 in dogs
L6-L7 in cats and small dogs (end of spine) (lumbar subarachnoid space)
What size needle should you use when taking a CSF sample?
Cervical: 1.5 inch needle, 21-22G
Lumbar: 1.5-3.5 inch needle, 21-22G
What is a pleocytosis?
An increased cel count, usually WBCs
For which conditions may you see a neutrophilic pleocytosis in a CSF sample?
(Increased neutrophils) SRMA (steroid-responsive meningitis arteritis) Bacerial infection Granulomatous meningitis Necrotising encephalitis Fungal FIP Post-myelography, haemorrhage, trauma, neoplasia
For which conditions may you see a mononuclear pleocytosis in a CSF sample?
Granulomatous meningitis Necrotising encephalitis CNS lymphoma Viral (distemper) Bacterial and steroid-responsive meningitis arteritis
For which conditions may you see a mixed pleocytosis in a CSF sample?
Granulomatous meningitis Bacterial and steroid-responsive meningitis arteritis Fungal Protozoal Non-inflammatory disease (infarction)
For which conditions may you see an eosinophilic pleocytosis in a CSF sample?
(Uncommon) Eosinophilic meningitis Fungal Protozoal Parasitic
What is myeography?
Administration of contrast agent to subarachnoid space to outline the spinal cord
Highlights space-occupying lesions as deviations or thinning of contrast column
CT is good for diagnosing what?
Trauma
Haemorrhage and middle ear disease
Fair for tumours and IVDD
What is electrodiagnostics?
Recording of electrical activity of muscles or neuronal structures
Can be spontaneous or in response to stimulation
What is electromyography (EMG)?
Records spontaneous muscle electrical activity
Normal muscle at rest is electrically silent
Destabilisation of the muscle cell membrane results in spontaneous discharge and so identifies damaged or denervated muscles and lesions
What do nerve conduction velocities (NCV) do?
Evaluate peripheral nerve function by stimulating a nerve at 2 different locations and recording:
- Amplitude of response (strength)
- Latency of response (how long it takes to get there-to calculate velocity)
What do velocities and amplitude represent on an nerve conduction velocity test?
Velocities: myelin
Amplitude: axon
What do repetitive nerve stimulation tests do?
Evaluate neuromuscular junctions (eg myasthenia gravis)
If amplitude decreases by >10%, suggestive of disease
What do F wave tests do?
Evaluate nerve roots and proximal part of peripheral nerves
Lost/delayed F waves if nerve roots are damaged
What do electroencephalography (EEG) tests do?
Record spontaneous electrical activity in cerebral cortex. 5-12 electrodes on head.
Good for:
-Detecting seizures
-Localising seizure focus
-Monitoring response to AEDs (automated external defibrillators) in cases with epilepsy
-Brain death
What do brainstem auditory evoked response (BAER) tests do?
Screening tool for detection of congenital sensorineural deafness
Determines hearing threshold in adults
Assess neural lesions on CNVIII or brainstem
Assess for brain death
Why do we take muscle and nerve biopsies when diagnosing neuro disease?
Mainly to differentiate between inflammatory and non-inflammatory (metabolic, degenerative) disaese
How big should a muscle biopsy be?
0.5 x 0.5 x 1.0cm
How big should a nerve biopsy be?
1/3 the width for 1cm
Which nerve is commonly biopsied?
Peroneal nerve (cranial tibia mucsle) (easily identified, is both motor and sensory)
Give some neurological deficits of the forebrain
- Altered mental status (depressed/disorientated)
- Contralateral blindness (decreased menace but normal PLR)
- Normal gait
- Circling (ipsilateral), head turn, head pressing, pacing
- Reduced postural responses in contralateral limb (tells you the lesion is rostral to midbrain)
- Normal to increased spinal reflexes and muscle tone
- Seizures, behavioural changes, hemineglect syndrome
How would you identify the location of a lesion using postural reactions?
- Lesions rostral to the midbrain (eg forebrain) -> contralateral reduced responses
- Lesions caudal to the midbrain (eg SC) -> ipsilateral reduced responses
Give some neurological deficits of the midbrain
- Depression, stupor, coma
- Cranial nerve deficits, possible vestibular signs
- Paresis of all or ipsilateral limbs
- Possible decerebrate rigidity
- Reduced postural responses in all/ipsilateral limbs
- Normal to increased spinal reflexes and muscle tone
- Resp or cardiac abnormalities
Opisthotonus with hyperextension of
all four limbs reflects a lesion where?
Brainstem
Give some neurological deficits of the cerebellum
- Normal mentation
- Ipsilateral menace deficit, normal vision, possibly vestibular signs
- Possibly decerebellate rigidity (hyperextended FLs, spastic flexion of hips)
- Intention tremors
- Truncal ataxia, broad-based stance, hypermetria
- Delayed then hypermetric postural responses
- Normal spinal reflexes and muscle tone
- Rarely increased frequency of urination
Hyperextension of the forelimbs and spastic flexion of the hips reflects a lesion where?
Cerebellum
What is meant by ‘white shakers’?
-Idiopathic cerebellitis, idiopathic tremor syndrome
-Mostly small breeds, young dogs
-Fine tremor, worse with stress/excitement
+/- head tilt/decreased menace/ leaning and falling, ataxia
How do you diagnose white shakers?
CSF-mildly inflammatory
How do you treat white shakers?
What is the prognosis like?
Corticosteroids for 4-6 months +/- other immunosuppressive drugs
Good prognosis, may relapse
What are the 3 main methods of infection of bacterial meningitis?
- Haematogenous
- CSF
- Direct invasion (eg inner ear, eyes, bite wounds)
Give some clinical signs of bacterial meningitis
Usually acute:
- Obtundation and cranial nerve deficits
- Neck pain
- Pyrexia
- Neutrophilia (50% of cases)
How would CSF be affected by bacterial meningitis?
- Increased protein concentration
- Pleocytosis (increased lymphocytes)
- Phagocytosed organisms (rare)
How do you treat bacterial meningitis?
- Antibiotics
- Surgical drainage
- Guarded prognosis
Give some clinical signs of increased intracranial pressure
- Altered mental status: obtunded, stupor, coma
- Altered pupil function: anisocoria, miosis, mydriasis
- Posture: decerebrate or decerebellate
- Bradycardia and hypertension (Cushing’s reflex)
- Physiological nystagmus
What is the oculocephalic reflex?
- When you move head, eyes should follow
- May be absent in comatose patients with brainstem dysfunction eg head trauma
How should you treat a patient with head trauma?
- ABC
- Oxygenation
- Restore blood pressure
- Fluid therapy (avoid glucose)
- Analgesia
How would you treat raised intracranial pressure?
- Mannitol (decreases blood viscosity) followed by crystalloid fluid therapy to prevent dehydration eg normal 0.9% saline (CI in hypovolaemia)
- Or hypertonic saline (4mg/kg 7.5% as slow bolus) (CI in hyponatremia)
Give some general care you should consider when treating a patient with head trauma
- Keep head elevated
- Avoid jugular compression
- Turn every 4-6 hours
- Catheterise bladder
- Nutritional support (tube feeding)
What should you not give to patients with head trauma?
Corticosteroids
What is hydrocephalus?
Abnormal dilation of the ventricular system within the cranium
Which kinds of dogs are affected by hydrocephalus?
Toy breeds, young age
Give some clinical signs of hydrocephalus
- Domed head
- Persistent fontanellae
- Abnormal behaviour
- Cognitive dysfunction
- Seizures
- Obtundation
- Circling/pacing
- Vestibular signs
How do you treat hydrocephalus?
- Medical: corticosteroids, furosemide, anti-epileptic drugs
- Surgical: ventriculoperitoneal shunt (drains fluid from ventricles into abdomen)
What is lissencephaly?
Which breeds are predisposed to it?
- No development of gyri and sulci
- Llasa apso, Korat cats
Give some clinical signs of lissencephaly
-Seizures and behavioural changes
What are hydronencephaly and porencephaly?
Presence of cerebral cavities, usually communicating with subarachnoid space and/or lateral ventricles
Give the clinical signs of hydronencephaly and porencephaly
- 1st few months: circling, abnormal behaviour
- Up to a few years: seizures
What is hepatic encephalopathy?
Liver dysfunction -> toxins in blood -> brain dysfunction
-Caused by acute liver failure or congenital portosystemic shunt
Give some clinical signs of hepatic encephalopathy
Mostly signs of forebrain dysfunction:
- Seizures
- Circling, head-pressing
- Abnormal behaviour
- Mentation changes (obtundation)
How do you diagnose hepatic encephalopathy?
- Blood ammonia levels
- Bile acids
- Liver US or CT
How do you treat hepatic encephalopathy?
- Lactulose (reduces absorption of ammonia from gut)
- Antibiotics
- Restricted protein diet
- Anti-epileptic drugs
- Surgery
Give the clinical signs of hypocalcaemia
- Muscle spasm and cramping
- Muscle twitching, trembling, stiffness
- Mental depression
- Tonic-clonic spasm
- Episodic rigidity
- Tetraparesis
- Seizures
Give the clinical signs of hypercalcaemia
- Muscle spasm and cramping, muscle twitching -Trembling
- Mental depression
- PU/PD
- Constipation
Give some causes of hypernatremia (high blood sodium)
- Excess water loss
- Excess salt intake
- Insufficient water intake
- Brain abnormalities
Give the clinical signs of hypernatremia (high blood sodium)
-Changes in mentation and seizures
How do you treat hypernatremia (high blood sodium)?
Correct sodium levels slowly over 48-72 hours
What is a storage disease?
- Defect of a lysosomal hydrolase enzyme
- Accumulation of storage substrates within the cytoplasm (mainly of neurons) -> cellular dysfunction -> diffuse neurological dysfunction -> progressive -> death
How do you manage storage diseases?
- No treatment
- Symptomatic treatment eg anti-epileptic drugs, anti-anxiety drugs
Give some causes of hypoglycaemia
Insulinoma, hepatic dysfunction
Give some clinical signs of hypoglycaemia
- Anxiety, lethargy, depression
- Ravenous appetite, exercise intolerance
- Tremors, visual deficit, seizures, coma
How do you diagnose hypoglycaemia?
Blood glucose <3mmol/L and clinical signs
How do you treat hypoglycaemia?
- Direct administration of glucose in emergency
- Frequent feeding in chronic cases
- Treat underlying cause
Give some primary neoplasms of the brain
- Intra-axial glial cell tumours
- Extra-axial meningiomas, choroid plexus tumours
How do you diagnose brain tumours?
- MRI (sometimes CT)
- CSF analysis (to rule out inflammatory disease)
How do you treat brain tumours?
- AEDs (anti-epileptic drugs)
- Anti-inflammatory dose of corticosteroids to reduce cerebral oedema
- Surgery +/- radiotherapy
What is Lafora’s disease?
- Neuronal glycoproteinosis
- Progressive myoclonic epilepsy
- Jerking (myoclonic) which is induced by flashing lights, sudden sounds and movements
- Wire-haired Dachshund and Basset Hound; rare
How do you treat Lafora’s disease?
- Antioxidant-rich diet
- Avoid starchy/sugary treats
- Treat epilepsy symptomatically (eg KBr)
Give some clinical signs of vestibular disease
- Head tilt (ipsilateral)
- Vestibular ataxia and wide-based stance
- Nystagmus
- Leaning and falling, sometimes tight circling
- Positional strabismus
Is a vertical nystagmus normally caused by a defect in the central or peripheral vestubular system?
Central
What is a cerebrovascular accident?
- Stroke
- Rapid loss of brain function due to a disturbance in blood supply to the brain
What are the 2 types of cerebrovascular accident (stroke)?
- Ischaemic (majority; results from aterial/venous obstruction)
- Haemorrhagic (results from rupture of blood vessels)
How do you diagnose a cerebrovascular accident (stroke)?
MRI
Give some concurrent medical conditions that could lead to a cerebrovascular accident (stroke)?
- CKD
- Hypertension
- Hyperadrenocorticism (Cushings)
What is an MUO?
Meningoencephalomyelitis of unknown origin