Clin Med - Neuro 4

drraythe's version from 2016-03-15 02:32

Neuroimaging: Radiography

Question Answer
Radiography is described in terms of...Opacity
What state should the PTx be in when you are performing neurodiagnostics?All require very sedate or anesthetized PTx
What should you know about positioning of the PTx when performing neurodiagnostics?Proper positioning obv.... SYMMETRY is helpful
What does a myelography look at?The spine
What can computed tomography look at?Spine & skull (brain)
Magnetic resonance imaging can look at?Brain & spinal cord
What's an Orthogonal view & which imaging technique has this?When a 3d object is looked at in 2d-which means this is a RADIOGRAPH (described in terms of opacity). there is NO cross-sectional imaging
When might you you do radiographs on the head?(Not as useful as other methods, however) Can be used to evaluate for skull fractures, dz of the middle ear
If you are going to do radiographs of the spine, what must you keep in mind? What must you do to have a good image?They must be perfectly straight if you wanna take a spine rad!! be sure to collimate to the area of interest
*What can you DEFINITIVELY DIAGNOSE w/ a spine radiograph? (4)Vertebral malformations
Trauma (fracture, luxation, subluxation)
Degenerative disk dz
*What can you PRESUMPTIVLY DIAGNOSE w/ a spine radiograph? (3)Intervertebral disk extrusion
Wobbler syndrome
Certain tumors
Whats a Hemivertebra, how can you dx?When only half of the vertebral body formed (kinda czs a wedge shape) & can be dx w/ rads
How can you dx spina bifida w/ radiographs?Look for the missing spinous processes on your image
Atlanto-axial subluxation can be dx w/ a radiograph but looking at how theyre dislocated from each other. what is a reason that an animal might be prone to this problem which you can pick up on rads?A missing dens, which would usually help keep the atlas & axis together
How can Diskospondylitis be dx from a radiograph?You can see an open space & a moth-eaten appearance of the bone
If you have Suspected Spinal Trauma & wish to do radiographs, what are 2 special precautions you should take when doing them?(1) If possible, hold off on sedation until radiographs are obtained → their tense muscles might actually be holding something important together
(2) Use of a horizontal beam (beside instead of above them, so you don't have to flip them to take a different view) → Sometimes just 1 view will have to do!
3 ways to dx INTERVERTEBRAL DISK DZ w/ a radiograph?(1) Shape & size of intervertebral disk space
(2) Shape, size & opacity of intervertebral foramen ("horse head" or "snoopy head")
(3) Size of articular facet joint space
What is a Myelography, why would you do 1 (what can you assess)?You inject iodinated contrast intrathecally (in subarachnoid space) so you can evaluate the subarachnoid space & extrapolate information about the spinal cord (you can't see the spinal cord tho)
What are the 3 abnormal patterns you can see on a myelography?Extradural
Intradural (extramedullary)
Intramedullary (spinal cord swelling or edema) (see slide 17 for pic of each in diagram form)
**Myelography → in what situations might you see an EXTRADURAL pattern?***IVDD → intervertebral Disk Dz**! Also can see w/ extradural masses such as a hematoma, lymphoma, or 1° bone tumor
**Myelography → you would see an Intradural, Extramedullary Pattern in what situations?Meningioma** (golf tee sign), or a nerve sheath tumor
What unique sign will you see if there is a meningioma & you perform a myelography?"GOLF TEE SIGN" = looks like a gold ball sitting on a golf tee sideways (*this is an intradural/extramedullary pattern)
When would you see an intramedullary pattern on a myelograph?Spinal cord sweling/edema

Neuroimaging → Computed Tomography (CT) & Magnetic Resonance Imaging (MRI)

Question Answer
CT is described in terms of?Density
Attenuation (saying opacity is ok tho)
CT is useful what ___ or ___ lesionsMineralized or bony
If it involves ____, CT will be helpfulBones
Can you do cross sectional imaging w/ CT?Yes!
How might you make a CT image even more accurate?Can be used w/ IV contrast, can be combined w/ myelogram
Can you image in multiple planes w/ CT?Yes, w/ a little difficulty. If you Reposition PTx for dorsal plane (head), you can reconstruct for sagittal plane. You can Reconstruct for sagittal & dorsal planes (spine)
6 dzs of the vertebral column where CT is useful to use?Hansen type I intervertebral disk dz (Acute onset often in young chondrodystrophic breeds)
Lumbosacral stenosis
Wobbler syndrome, trauma & Destructive tumors
2 dzs of the head where CT is useful to use?Trauma, focal tumors of the forebrain
What is wobblers dz?Cervical stenotic myelopathy, a compressive cervical spinal cord syndrome czd by vertebral canal stenosis, articular process osteophyte proliferation & vertebral body tipping
MRI is described in terms of?Intensity
What kind of tissue is MRI best for looking at?Excellent soft tissue resolution
Can you see different planes in MRI?Yes! Image in 3 planes w/o repositioning
MRI is good for looking at...Use for the brain & spinal cord
How can you make MRI even more specific/accurate?Can use contrast
How can you change up the MRI machine to target specific things?You can use different sequences for different affects. (She said you don't have to remember, however in the notes it says for the BRAIN you can use: T1 (pre-& post-contrast), T2, FLAIR, T2°, diffusion-weighted imaging..... & for the SPINE you can use: T1 (pre-& post-contrast), T2, STIR, HASTE, T2°)
What are 6 dzs of the BRAIN you can look at w/ an MRI machine?Tumors
Congenital malformations
Inflammatory dz
Senile changes/cognitive dysfxn
(all soft tissue stuff!)
8 dzs of the SPINAL CORD/ NERVE ROOTS you can look at w/ an MRI machine?Intervertebral disk dz (BOTH types)
Fibrocartilaginous embolism
Neural tumors
Lumbosacral stenosis
Wobbler syndrome
Atlantoaxial subluxation
How should the PTx be when you are taking MRIs?Anesthetized
Does an MRI have better resolution on a smaller or larger PTx?Better res on a larger PTx
Better resolution depends on what (of the machine?)↑er field strength
Will fluid appear darker or lighter on an MRI?Brighter/whiter

Lab Tests & Cytology/ Other tests

Question Answer
What are some other lab tests you can do in addition to neuroimageing?Complete blood count
Chem panel
Endocrine testing
Infectious dz titers
Miscellaneous testing
What might Peripheral neutrophilia on the CBC indicate?Steroid responsive meningitis-arteritis
What 2 things on a chem panel might indicate/cz a neuro problem?Muscle enzyme elevation
Electrolyte abnormalities
Which 2 endocrine disorders are you most likely to see neuro problems w/?Cushing’s syndrome
What are some infectious tick-bourne dzs which can cz neuro problems in dogs that you can test for?RMSF, E. canis
What are some viruses which can cz infectious dzs of the neuro system in dogs that you can test for?Canine Distemper Virus
What are some parasites (protozoa) which can cz infectious dzs of the neuro system in dogs that you can test for?Neospora
What is a fungi which can cz infectious dzs of the neuro system in dogs that you can test for?Blastomyces
What is a bacteria which can cz infectious dzs of the neuro system in dogs that you can test for?Bartonella
What are some viruses which can cz infectious dzs of the neuro system in cats that you can test for?Coronavirus/FIP, FeLV, FIV
What are some fungi which can cz infectious dzs of the neuro system in cats that you can test for?Blastomyces, Cryptococcus & Others
What is a parasite (protozoa) which can cz infectious dz of the neuro system in cats that you can test for?Toxoplasmosis
If you suspect Myasthenia gravis, what test can you do?Anti-acetylcholine receptor Ab titer
If you suspect Masticatory muscle myositis, what test can you do?Anti-type II M muscle Ab titer
Miscellaneous Testing → Therapeutic drug monitoring → what are 2 anticonvulsants you can monitor?Phenobarbital & Bromide
What are 2 bing things you check for w/ Cerebrospinal Fluid (CSF) Analysis?↑ number of WBCs in fluid of CSF (this is pleocytosis) or an ↑ amount of protein
What is pleocytosis & how do you check this?↑ number of WBCs in fluid of CSF, check w/ a Cerebrospinal Fluid (CSF) Analysis
Why would you never want to do a CSF tap if there is ↑ intracranial pressure (such as there is a tumor)? what should you do?Bc you can cz brain herniation (brain rapidly moves toward lower pressure gradient)-& this can happen w/ a lumbar OR cisternal tap. DO IMAGING 1st & only do CSF tap if absolutely necessary
What is Pithing? when is it a risk?This is when you directly stab the brainstem & can happen w/ a cisternal CSF tap
How often does CSF tap provide a definitive Dx? what can a CSF tap do for you?Rarely yields definitive Dx, but does add to our pile of information
What are 5 types of electrodiagnostics?Electromyography
Nerve conduction velocity
Repetitive nerve stimulation
Brainstem auditory evoked response & Electroencephalography
What does Electromyography test for? What can it tell you?Detects abnormal muscle cell membranes - such as denervation, an axonal dz, or 1° mm dz
What does a Nerve conduction velocity test tell you?Tells you about abnormalities in myelination - this can pertain to motor OR sensory nerves
A Repetitive nerve stimulation test might help you determine...?Might be Helpful for some disorders of the neuromuscular junction, like Myesthenia Gravis or Botulism
How does myesthenia gravis present w/ a Repetitive nerve stimulation test?Looks like Decremental response (aka reduced response each time)
How does botulism present w/ a Repetitive nerve stimulation test?You will see Pseudofacilitation, ie, appears to get better
Brainstem Auditory Evoked Response can diagnose what 2 things?Deafness (is it congenital aka Sensorineural, or is it acquired aka conduction?) & brain(stem) death
Electroencephalography → what is this test doing? what can it be used for?It does A Recording of spontaneous brain activity, which can confirm seizure focus. (Not used much clinically but Could be useful to determine nonconvulsive seizures)
Histopathology → what often leads to definitive dx?Necropsy :(
What can a brain biopsy tell you about?Cerebral dz, tumor removal