PRACTICAL: Neurology and diagnostic imaging and pathology

Question 1

Appearance- hydrocephalus on MRI

Answer 1

• T1w black (water) - T2w = white appearance (water

Question 2

Appearance - hydrocephalus

Answer 2

• domed head - open fontanelle - diverging strabismus

Question 3

Tx - hydrocephalus in SA

Answer 3

• MEDICAL: -GCs (low dose) - Acetazolamide (diuretic) - Omeprazole (proton pump inhibitor) - Mannitol (emergency diuretic) - SURGICAL: ventriculoperitoneal shunt placement

Question 4

Aetiology - hydrocephalus

Answer 4

congenital or acquired

Question 5

4 typical radiographic features of IVDD

Answer 5

1. increased opacity over intervertebral foramen 2. mineralisation of IVD 3. narrowed IVD space 4. spondylosis

Question 6

What is Hansen type 1 IVDD?

Answer 6

• chondroid degeneration - extrusion of degenerate nucleus - acute –> SC trauma, contusion, compression

Question 7

What is Hansen type 2 IVDD?

Answer 7

• fibroid degeneration - protrusion of hypertrophied annulus –> chronic compression of SC, may present acutely.

Question 8

Surgical tx options of IVDD type 1

Answer 8

• THORACOLUMBAR HEMILAMINECTOMY: removal of half lamina, the articular facet joint and pedicle allowing access to vertebral canal from lateral approach - CERVICAL SPINE - VENTRAL SLOT = a ‘slot’ is burred through the centre of the disc and adjacent vertebral endplates to gain access to vertebral canal from ventral approach

Question 9

What is myelogram used for?

Answer 9

to show SC compression

Question 10

What is a T1w MRI?

Answer 10

magnetisation allowed to recover before measuring MR signal by changing the repetition time (TR). To assess cortex, fatty tissue etc

Question 11

What is a T2w MRI?

Answer 11

magnetisation allowed to decay before measuring the MR signal by changing echo time (TE). Used to detect oedema, inflam.., white matter lesions

Question 12

Whic infectious diseases would you want to r/o to reach a dx of MUA (such as GME)?

Answer 12

• VIRAL ENCEPHALITIDES (canine distemper) - PROTOZOAL ENCEPHALITIDES (toxoplasma, neosporosis) - FUNGAL ENCEPHALOMYELITIDES (cryptococcosis)

Question 13

How can supratentorial brain tumours cause pain?

Answer 13

d/t increased ICP

Question 14

What is the supratentorial region?

Answer 14

the region above the tentorium cerebelli (the extension of the dura mater which separates the cerebellum and occipital lobes)

Question 15

Outline SRMA

Answer 15

= steroid responsive meningitis and arteritis - differentiate from GME (by CSF cells) - may be febrile - young dogs - neuro exam normal - cervical +/- spinal hyperaesthesia - at risk of haemrrhage into vertebral canal

Question 16

Describe gross lesions of SRMA

Answer 16

haemorrhage and inflammatory lesions located within spinal cord

Question 17

Which structures can cause pain in spinal cord

Answer 17

• meninges - articular process - spinal nn - vertebral body

Question 18

What do disc herniations usually cause?

Answer 18

• usually cause a myelopathy EXCEPTIONS: 1. in cervical spine, there is more space and a dorsal longitudinal ligament so some animals may have pain only 2. lateralised disc herniations that only affect nn root

Question 19

Give 2 examples of a neoplasia that may affect multiple segments of spinal cord

Answer 19

myeloma and lymphoma

Question 20

ddx - spinal ataxia in horses

Answer 20

• CVM/S - EHV-1 myeloencephalitis - EDM - trauma - migrating parasites - EPM (foreign imports) - ryegrass staggers

Question 21

Tx - EHV-1

Answer 21

• Supportive (prevent injury such as self-trauma whilst standing and whilst recumbent and whilst showing neuro signs - Fluids and anti-inflammatories - No approved antivirals

Question 22

Outline EHV-1 replication and shedding

Answer 22

replicates in nasal eithelium, shed in nasal secretion within 24 hours, usually for 7 days, for up to 14 days if horse is immuno-naive

Question 23

Dx - EHV-1

Answer 23

virus isolation and typing (look for specific mutation that causes neuro signs rather than commner rhinopnemonitis strains)

Question 24

Outline spread of EHV-1 in body

Answer 24

it is epitheliotropic and disseminates to uterus, lung, CNS –> virus invades ECs –> vasculitis and thrombo-ischaemia (peripheral vasculitis –> limb oedema, SC vasculitis, immune complex deposition)

Question 25

What should you ensure when taking equine cervical radiographs?

Answer 25

ensure ventro-lateral processes aligned for good quality - otherwise measurements are invlaid

Question 26

What structures pass out of intervertebral foramina?

Answer 26

• spinal nn root - DRG - spinal artery of segmental artery - veins - ligaments

Question 27

Describe how intrAvertebral ratios can help with a CVM/S diagnosis?

Answer 27

• If ratio is

Question 28

What is another name for ‘ski ramping’?

Answer 28

caudal epiphyseal flare (this describes a triangle of new bone into the spinal canal)

Question 29

Outline dynamic stenosis (CVM type 1)

Answer 29

• when neck is flexed or hyperextended, the vertebrae move excessively causing cord compression - commonly C3-5 - younger horses - often worse with flexion (C3-5) and extension (C5-7)

Question 30

Outline absolute stenosis (CVM type 2)

Answer 30

• osseous change in vertebrae –> spinal cord compression - usually older horses - C5-7 - OA changes in AP joints (facets) may be result of congenital OCD - other malformed vertebrae

Question 31

What is Wallerian degeneration?

Answer 31

• associated with CVM/s - associated with ascending tracts cr. to lesion - white + grey matter changes at lesion - descending tracts cd to lesion