Tarc: Neuro Imaging And Diagnostics Flashcards
Clinical signs nd pathogenesis of hydrocephalus
- congential (more common dogs) or acquired
- domed head shape
- open fontanel
- diverging strabismus
- blindness with absent menace OU
- ataxia and v postural reactions
> on imaging - thin cortex w/ greatly distended lateral ventricles
Best diagnostic modalities for diagnosing hydrocephalus?
- MRI
- CT
0 Ultrasound
Tx hydrocephalus?
> medical - low dose GCs - acetazolamide - omeprazole - mannitol (emergency) > surgical - ventriculoperitoneal shunt placement
What breeds hav ^ risk of hydrocephalus?
- toy breeds with brachycephalic skulls
How long after ventriculoperitoneal shunt sx are clinical signs likely to improve?
4 months
WHat proportion of animals are likely to develop shun complications following surgery for hydrocephalus?
25%~
What radiographic abnormalities indicate IVDD?
- ^ opactiy over intervertebral foramen
- mineralisation of intervertebral disks
- narrowed intervertebral disk space
- spondylosis
What is the intervertebral disk made up of?
- annulus fibrosus
- nucleus pulposus
What is the SC surrounded by?
Epidural fat
What 3 planes can CT/MRI be taken in?
- transverse
- median/sagittal
- dorsal
How can a cervical vertebrae e identified on MRI?
Only vertbrae to contain BVs
What are the 2 types of IVDD?
> type 1 (Hansen) EXTRUSION - chondroid degeneration - extrusion of degenerate nucleus - acute -> spinal cord trauma (contusion and/or compression) > type 2 (Hansen) PROTRUSION - fibroid degeneration - protrusion of hypertrophied annulus > chronic compression of SC - may still present acutely
Tx IVDD?
> thoracolumbar spine: Hemilaminectomy
- removal of half the lamina, articular facet joint and pedicle allowing access to vertebral canal from a lateral approach
cervical spine: Ventral slot
- slot burred though the centre of the disk and adjecent vertebral endplates to gain access to vertebral canal from ventral aproach
Can radiographs dx disk disease?
No, but can indicate disk diseas
- myelography needed for dx
Where is the most common space for IVDD?
T13- L1
What is present above the disk hat -> asymetrical signs of IVDD?
longitudinal ligament along dorsal aspect of annulus fibrosus
WHERE IS CONTRAST INJECTED FOR A MYELOGRAM?
SUBARACHNOID SPACE
What is decision to go to surgery for IVDD based upon?
- pain
- progression
- deep pain/neuro deficits severity
Ddx for a chronic progressive asymmetrical painful forebrain dz. What about if ^ cellularity (mononuclear cells) found on CSF tap
> Neoplastic
- supretentorial tumours cause pain d/t ^ICP
infectious/inflam
with CSF findings > GME (magnitude and type of pleiocytosis will vary in this condition)
Histo findings associated with GME
- mononuclear inflammatory cells
- located perivascularly (around the BVs)
> macroscopically brownish lesions seen in the white matter (enlarged sie of brain w/ oedema and inflammatory focus)
What is SRMA?
- steroid responsive meningitis arteritis
(acute, progressive, symmetircal, painful) - inflamamtory cells (mainly neutrophils) within meninges and around BVs and nerve roots
- young dogs commonly
- may be febrile
- usually neurologically normal
- cervical hyperaesthesia (+- spine)
- risk of haemorrhage into vertebral canal
What is GME?
- granulomatous meningioencephalitis
- a type of MUA (meningitis of unknown origin)
What would a population of small, mature lymphocytes on CSF tap indicate?
inflmmation - MUA
How si GME dx confirmed?
PME
Tx MUA?
Cytarabine
What would a CSF tap of marked pleiocytosis, predominanty neutrophils give as Ddx?
- SRMA (no and type of pleiocytosis may vary in this condition)
- infectious
- neoplasia (eg. meningiomia)
- IVDD (can -> neutrophilic pleiocytosis)
How do nerves respond to damage?
SWELL!
Ddx for spinal ataxia in the horse
- CVM/S
- EHV1
- EDM
- trauma
- migrating parasites
- EPM (foreign imports)
- ryegrass staggers
Clinical signs of EHV1 infection?
- ascending paresis/ataxia
- systemic signs: pyrexia, depression
- bladder incontinence, tail paresis
- urine scalding
- occasionally cranial nerve signs
Pathogenesis of EHV1?
> transmission
- inhalation: aerosolised infective droplets
- fomites: hands, water, eeed
viral replication in nasal epitheliem and shedding in nasal secretions
- within 2hrs
- usually for 7d, up to 14d in immunologically naive horses
Which part of the SC does EHV1 mostly affect?
- grey matter (vasculitis and thrombosis -> sharply demarcated haemorrhage)
What causes the clinical signs of EHV?
result of vascular compromise (extent of neuro deficit correlates to haemorrhage)
How can EHV1 be diganosed?
> IHC
- vial antigen in endothelial cells and myocytes surrounding BVs
- first detected @6-8d post infection
Pathogenesis of EHV1
- endotheliotopic
- dissemination to uterus, lung or CNS, then to endothelium
- vasculitis and thrombo-ischaemia (peripheral vasculitis (limb oedema), SC vasculitis, immune complex deposition)
- some strains more liekly to be associated with neuro form of dz
What codes of practice hsould be consulted for appropriate measures around EHV1 disease?
HBLB
Tx EHV1
Look up
Management of an EHV1 outbreak?
Look up
How can good quality standing radiographs of the cervical spine be judged?
Ventrolateral processes should be perectly aligned
What boney changes are ofen seen in older horses? Are these pathological?
- articular face changes @ C5-C7 common in adult healthy horses
- NOT neurological
What radiographic signs may indicate Opathology of the spine?
> subjective
- spinal canal aligment
- OA of articular processes
- caudal epiphyseal flare (ski ramping)
objective
= intRAvertebral ratios (more senstiive and specific in young horses)
- measure minimum canal diameter (perpendicular to canal floor) and maximum vertebral physis diameter (perpendicula to canal floor)
- calculate ratio (canal/physis) to adjust for distance of radiograph from xray machine and size of horse
- if
If ratio of
No not necessarily
Pathogenesis of CVM/S. What are the 2 types?
> neuro signs d/t progressive SC compression
2 main types of osseus malformation/stenosis
- type 1: dynamic (flexion C3-C5, extension C5-C7, young animals)
- type 2: absolute (osseus changes in vertebrae -> SC compression, older horses @ C5-7, O changes in articular process joints (facets) d/t congenital OCD?)
How may the location of the lesion be determined at PME with CVMS?
> Wallerian degeneration
- ascending tracts cranial to the lesions and descedning tracts caudal to the lesion degenerate
- white and grey matter changes at site of lesion
Outline the flow of CSF
- produced choroid plexus of lateral ventricles
- flows into 3rd ventricle then 4th
- exits via arachnoid villi to the lymphatics
