Neurology: Diagnostic Tests Flashcards
What diagnostic tests can be used for neuology?
Neurological examination- best
* Blood tests
* BP
* Urinalysis
* Faecal analysis
* Imaging
* CSF analysis
* Functional testing
* Biopsies
What causes diagnostic challenges in neurology?
- CNS is well protected- bone, BBB
- Lack of functinoal reserve and poor regen capacity
- Combination of specific and non-specific tests
- Diagnosis of exclusion
What are the three causes of seizures?
- Idiopathic epilepsy- genetic or presumed genetic in origin
- Structural epilepsy- inflammatory, neoplastic, traumatic
- Reactive seizures- seizure occuring as a natural response from the normal brain to a transient disturbance in function- metabolic or toxic
What are diifferentials for seizures?
- Vascular- ishaemic encephalopathy
- Infecitous- meningoencephalitis
- Trauma- truamtic brain injury
- Anomalous- hydrocephalous, congenital malformation
- Metabolic- hepatoc encephalopathy, renal encephalopathy
- Idiopathic
- Neoplastic
- Degnerative
How is idiopathic epilepsy diagnosed?
Diagnosis of exclusion
What about blood tests can be used for investigation of seizures?
- Haematology and biochem- electrolytes, Ca and Glu
- Liver function testing
- ± endocrine function tests
- ±clotting factor
± infectious disease
What infectious diseases can cause seizures?
Dogs
* Neospora caninum
* Toxoplasma gondii
* CDV
* Angiostronglyus
Cats
* Toxoplasma gondii
* FeLV
* FIV
* FIP
* Cryptococcus
When can urinalysis be useful for investiagion of seizures?
Rule out primary conditions
* Cerebrovascular accident- cushings/hypoproteinuria
* Discospondylitis- UTI primary cause
* Paraparesis/urinary dysfunction- increased risk of UTI
* Inborn errors of metabolism - unusual metabolites
What are the disadvantages of MRI?
- Contrast required
- Anaesthesia
- High cost
- Limited availability
- Artefacts
- What is CSF analysis most useful for?
- What else can cause abnormalities?
- What are its limitations?
- Infectious/inflammatory
- Neoplastic or traumatic conditions
- May not be abnormal due to location, can have non-specific changes, cell countr correlate with exfoliation into CSF not severity of disease
What are the contraindications of CSF?
- Increased intra-cranial position
- Coagulopathy
- Cervical collection in some conditions
What are the indications of increased intracranial pressure?
- Mental status
- Pupil size and PLR
- Abnormal postures
- Vestibular eye movement
How is CSF analysed?
Analysis within 1 hr
* Differential cell count
* Cytology
Equipment
* Spinal needle
* Collection pots
* Clippers, scrub, gloves
Site- cerebellomedullary cistern or lumbar cistern
What is normal for CNS analysis?
Gross
* Clear
Cell count
* RBC 0
* WBC < 5 ul
Cytospin
* Cytology
* Differential cell count
Protein
* Cervical < 30mg/dl
* Lumbar < 45mg/dl
PCR- infectious disease
What are different CSF abnormalities?
Blood contamination
Albuminocytological dissocation
* Increased protein without increased WBC
* Non-specific- neoplasia, vasculitis, trauma, syringomyelia, degen myelopathy
Pleocytosis- increased WBC
Other findings- infectious agents, neoplasia
When is Urine/Blood/CSF culture appropriate?
- Bacterial meningitis- blood and urine culture, disc aspirate
- Encephalitis- penetrating cranial injuries, extension from otitis media/interna
What is EEG?
Electroencephalography
* Assess forebrain activity
* Identification of seizure activity
* Can be useful in status epilepticus
How are spinal lesions localised?
What are the differentials for spinal neurolocalisation?
- Vascular- ishaemic myelopathy
- Infectious/inflammatory- meningomyelitis of unknown origin, discospondlylitis, toxoplasmosis, neosporosis, FIP, FeLV, SRMA
- Trauma
- A- AA instability, chiari-like malformation, vertebral abnormalities
- M- na
- I- na
- N- spinal/vertebral neoplasia
- D- intervertebral disc, cervical stenotic myelopathy, degenerative lumbosacral stenosis, degenerative myelopathy
How can the spinal patient be investigated?
- Blood tests- haematology, biochem, c-reactive protein, infectious disease testing
- Imaging- localise- MRI gold
radiography- good for bony, radiography, CT, Myelography - CSF analysis
- Culture
What are the following bony abnormalities?
- What is CT useful for in spinal patients?
- What are the contraindications for myelography?
- What is the purpose of myelography?
- Excellent for bony detail, rapid acquisition, contrast can be used
- Coaguloapthy, spinal instability, cloudy/turbid
- See the spinal cord- extradural or bony lesions
What are the three problems that can be identified of myelography?
Extradural
* Axial displacement of 1 or more contrast columns
* Columns often thin or partially disrupted at the site of the lesion
* Most common
* DDx- IVD herniation, vertebral stenosis, neoplasia
Intradural
* Filling defect within the contract column
* ‘Golf tee’ sign or widening of subarachnoid space
* DDX- neoplasia, arachnoide diverticulum
Intramedullary
* Divergence of contrast columns
* DDx- neoplasia, actue ishaemic myelopathy, contusion, haemorrhage, myelitis
What are the three problems that can be identified of myelography?
Extradural
* Axial displacement of 1 or more contrast columns
* Columns often thin or partially disrupted at the site of the lesion
* Most common
* DDx- IVD herniation, vertebral stenosis, neoplasia
Intradural
* Filling defect within the contract column
* ‘Golf tee’ sign or widening of subarachnoid space
* DDX- neoplasia, arachnoide diverticulum
Intramedullary
* Divergence of contrast columns
* DDx- neoplasia, actue ishaemic myelopathy, contusion, haemorrhage, myelitis
