Principles of Myelopathies in Large Animals Flashcards
What are the two main types of osseous malformation/ stenosis?
Type 1- dynamic- when vertebrae are moving
Type 2- absolute- ALL the time
What is Type 1 Dynamic Stenosis and what parts of the spine are affected?
spinal cord compression
effects-
C3-C5 in flexion
C5-C7 in extension
How do we diagnose Type 1 Dynamic Stenosis?
Best to use a Myelogram- insert contrast material into the sub arachnoid space
What causes Type 2 Absolute Stenosis?
Osseous changes in the vertebrae cause spinal cord compression- caused by age and osteoarthritic changes or as a result of congenital OCD/ malformed vertebrae
What parts of the spine are most commonly effected by Type 2 Absolute Stenosis?
C5-C7
Give an example of a congenital cause of Type 2 Absolute Stenosis?
Arabian foals- Occipitoatlanto-axial malformation (OAAM) where the atlas is fused to the base of the skull
In what ways can we diagnose CVM- Cervical vertebral compressive myelopathy?
Neurological exam
Standing cervical radiographs
Scintigraphy
CT scans (expensive!)
CSF analysis (rules out other disease processes)
What is Wallerian Degeneration?
Anterograde degeneration of the distal end of an axon that is a result of a nerve lesion- can be seen on spinal cross sections PM
What are inter/ intra vertebral ratios? What ratio is associated with spinal cord compression?
Minimum width across the spinal canal taken perpendicularly to either the roof or the floor- ratios less than 52% associated with spinal cord compression
Why do we measure inter/ intra vertebral ratios and not just measure them on X-Rays?
X-Rays diverge depending on how close/ far the plate is from the subject
What are the three main treatment options for equine vertebral malformation/ stenosis?
Pace diet- restricts growth of the foal by limiting protein intake
Articular process joint medication e.g. LA corticosteroids to reduce inflammation
Ventral stabilisation surgery- involves drilling out part of the vertebrae
What is an infectious cause of Equine Myelopathy?
EHV1- latency in trigeminal ganglion, causes abortion, ascending paresis/ ataxia, bladder incontinence
How would we recognise EHV1 in the spinal cord post mortem?
SYMMETRICAL haemorrhages throughout the cord with vasculitis & thrombosis
What is EDM aka Equine Degenerative Myelopathy and what causes it?
neuronal fibre degeneration and demyelination in white matter
Cause unknown but suggested to be Vitamin E deficiency or genetic predisposition
What are the clinical signs of EDM aka Equine Degenerative Myelopathy?
symmetric ataxia
hindlimbs more severely affected
hypoflexia over the trunk with reduced cutaneous trunci reflex
