Appearance- hydrocephalus on MRI
- T1w black (water) - T2w = white appearance (water
Appearance - hydrocephalus
- domed head - open fontanelle - diverging strabismus
Tx - hydrocephalus in SA
- MEDICAL: -GCs (low dose) - Acetazolamide (diuretic) - Omeprazole (proton pump inhibitor) - Mannitol (emergency diuretic) - SURGICAL: ventriculoperitoneal shunt placement
Aetiology - hydrocephalus
congenital or acquired
4 typical radiographic features of IVDD
1. increased opacity over intervertebral foramen 2. mineralisation of IVD 3. narrowed IVD space 4. spondylosis
What is Hansen type 1 IVDD?
- chondroid degeneration - extrusion of degenerate nucleus - acute --> SC trauma, contusion, compression
What is Hansen type 2 IVDD?
- fibroid degeneration - protrusion of hypertrophied annulus --> chronic compression of SC, may present acutely.
Surgical tx options of IVDD type 1
- 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
What is myelogram used for?
to show SC compression
What is a T1w MRI?
magnetisation allowed to recover before measuring MR signal by changing the repetition time (TR). To assess cortex, fatty tissue etc
What is a T2w MRI?
magnetisation allowed to decay before measuring the MR signal by changing echo time (TE). Used to detect oedema, inflam.., white matter lesions
Whic infectious diseases would you want to r/o to reach a dx of MUA (such as GME)?
- VIRAL ENCEPHALITIDES (canine distemper) - PROTOZOAL ENCEPHALITIDES (toxoplasma, neosporosis) - FUNGAL ENCEPHALOMYELITIDES (cryptococcosis)
How can supratentorial brain tumours cause pain?
d/t increased ICP
What is the supratentorial region?
the region above the tentorium cerebelli (the extension of the dura mater which separates the cerebellum and occipital lobes)
= 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
Describe gross lesions of SRMA
haemorrhage and inflammatory lesions located within spinal cord
Which structures can cause pain in spinal cord
- meninges - articular process - spinal nn - vertebral body
What do disc herniations usually cause?
- 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
Give 2 examples of a neoplasia that may affect multiple segments of spinal cord
myeloma and lymphoma
ddx - spinal ataxia in horses
- CVM/S - EHV-1 myeloencephalitis - EDM - trauma - migrating parasites - EPM (foreign imports) - ryegrass staggers
Tx - EHV-1
- Supportive (prevent injury such as self-trauma whilst standing and whilst recumbent and whilst showing neuro signs - Fluids and anti-inflammatories - No approved antivirals
Outline EHV-1 replication and shedding
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
Dx - EHV-1
virus isolation and typing (look for specific mutation that causes neuro signs rather than commner rhinopnemonitis strains)
Outline spread of EHV-1 in body
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)
What should you ensure when taking equine cervical radiographs?
ensure ventro-lateral processes aligned for good quality - otherwise measurements are invlaid
What structures pass out of intervertebral foramina?
- spinal nn root - DRG - spinal artery of segmental artery - veins - ligaments
Describe how intrAvertebral ratios can help with a CVM/S diagnosis?
- If ratio is
What is another name for 'ski ramping'?
caudal epiphyseal flare (this describes a triangle of new bone into the spinal canal)
Outline dynamic stenosis (CVM type 1)
- 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)
Outline absolute stenosis (CVM type 2)
- 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
What is Wallerian degeneration?
- associated with CVM/s - associated with ascending tracts cr. to lesion - white + grey matter changes at lesion - descending tracts cd to lesion