Ch 30 Medical neuro conditions Flashcards
determine the neuroanatomic localization (C1-C5, C6-T2, T3-L3, L4-S3 spinal cord segments) and lesion distribution (focal, multifocal, diffuse)
DAMNIT V
CSF
cytology and protein are relatively sensitive indicators of central nervous system disease, they are rarely specific for individual disease processes
Where can a CSF sample be collected?
What is the maximum volume which can be collected?
Cerebellomedullary cistern
Lumbar subarachnoid space
No more than 1ml/5kg
What are the landmarks for entering the cisterna magna?
What structures do you pass through?
Intersection of a line between the occipital protuberance and the spinous process of C2 and a line between the cranial aspect of the wings of the atlas
Pass through the skin, atlanto-occipital ligament and the meninges (dura mater and arachnoid)
What is the appropriate interarcuate space for lumbar CSF collection in dogs and cats?
L5-L6 in dogs
L6-L7 in cats
Spinal cord has tapered into the conus medullaris
How can you determine if haemorrhage within a CSF sample is iatrogenic?
What is xanthochromic CSF?
Centrifugation - clears iatrogenic haemorrhage
Yellow or straw-tinged CSF suggesting previous subarachnoid haemorrhage (in the absence of hyperbilirubinaemia)
What is the ideal timing for performing a cell count on CSF?
What can be done if this timing cannot be achieved?
Within 30min-1hr of collection
Refridgeration can help to stabilise the cells
Can add 1:1 dilution of hetastarch or autologous serum for stabilisation
If done, a seperate, unaltered alloquat should be provided for protein analysis
What is the normal WBC count of CSF in dogs and cats?
0-5 WBC x 10^6/L
What is the normal CSF protein content in dogs and cats?
From cerebellomedullary cistern less than 250mg/L (25mg/dL)
From lumbar cistern less than 450mg/L (45mg/dL)
Increased protein is nonspecific and indicates a damaged BBB or increased local intrathecal IgG production
CSF cahnges with dz
Bacterial meningitis: elevated protein, marked pleocytosis, neutrophilic
GME, SRMA: protien elevated, pleocytosis, monocytosis (neutophil is acute SRMA)
Neoplasia: variable
Degenerative: normal
vascular: variable
Serology
infectious disease
Toxoplasma gondii, Neospora caninum
What are the pros and cons of antigen vs antibody serology?
Antigen testing may circumvent the problems associated with interpretation of antibody testing
Antigen testing is insensitivie as it required the presence of the organism in the sample being tested
What is an IgG antibody index?
IgG Index = IgG CSF/ IgG serum
A low index suggests the IgG migrated across the BBB whereas an elevated index indicates theat the source of the IgG is the CNS
PCR
useful for the identification of small amounts of DNA (or RNA by reverse transcription PCR [RT-PCR]) from an infectious agent, PCR is not without pitfalls, and results must be interpreted carefully
flase positive
List 4 reasons that a negative PCR does not definitively rule out infectious meningoencephalitis
In individual OCR test may be inherently insensitive
Nucleic acids may be present in CSF at undetectable levels
Nuclei acids from organisms may be present within the CNS parenchyma but not in the CSF
The dirorder may have been triggered by a pathogen which is no longer present
imaging
limited contrast resolution provided by CT > limited value in identifying myelopathies, such as meningomyelitis or FcE.
main utility of CT is in excluding extradural compressive myelopathies
MRI > sensitive for differentiating among intramedullary disorders (e.g., meningomyelitis vs FCE) and for differentiating intramedullary from intradural/extramedullary lesions
List some examples of degenerative spinal diseases
LWN abiotrophy
Degenerative myelopathy
What is myelodysplasia?
An anomaly of the spinal cord resulting from incomplete closure or development of the neural tube
List some examples of metabolic spinal disease
Canine polioencephalomyelopathies
Globoid cell leukodystrophy
List some nutritional diseases of the spinal cord
Thiamine deficiency
Secondary hyperparathyroidism
Hypervitaminosis A (cat)
Define degenerative myelopathy
What breeds are overrepresented?
What genetic risk factor?
etiopathogenesis unnkown, genetic and environmental factors
Diffuse axonopathy associated with necrosis in lateral and ventral funiculi of the TL spinal cord
accompanied by secondary demyelination and astrogliosis
GDS, Corgis, Boxer, Rh. Ridgeback
Missense mutation in the superoxide dismutase (SOD1) gene causing progressive superoxide radical-induced axonal and myelin degeneration
dogs that are homozygous (two mutated alleles) are considered “at risk”
DM clinical signs
slowly progressive, nonpainful disorder
Neuroanatomic localization commonly is consistent at (T3-L3 myelopathy)
typified by a progressive UMN paresis and general proprioceptive ataxia in the pelvic limbs
10-20% lose patella reflex
Tx: Physical therapy may prolong survival time
complicated by concurrent orthopedic conditions
Clinical progression usually results in a nonambulatory status within 6 to 9 months of diagnosis.
Define SRMA
What breeds are overrepresented?
profound cervical hyperesthesia, depression, and pyrexia
A systemic immune disorder characterised by inflammatory lesions of the leptomeninges and associated arteries that typically respond to corticosteroids
Beagles, Boxers, Bernese Mt Dogs, Weimeraners, NSDT Retrievers
acute and second, more chronic form of steroid-responsive meningitis-arteritis may occur following relapses of acute disease and/or inadequate treatment.
What vessels can also be effected by SRMA? What other disease is often seen concurrently?
Vessels of the heart, mediastinum and thyroid glands
Occassionally concurrent IMPA
What acute phase proteins are elevated in the CSF of dogs with SRMA?
Dx
Tx
DX: baseline bloods, serology/PCR, imaging
CRP
alpha2-macroglobulin
Bacterial cultures of cerebrospinal fluid are negative
elevated IgA levels in both cerebrospinal fluid and serum
Tx: nsaid if mild
minimum of 6 months: Prednisolone or prednisone: 2 mg/kg/day, This dose is slowly tapered
econdary immunosuppressive drug is azathioprine (at 1.1 to 2.2 mg/kg PO every 48 hours)
monitor with CS, CRP or CSF
What are the three forms of GME?
Define GME
MUO antemortem
acute-onset, progressive, focal-to-multifocal
Disseminated
Focal
Ocular
An angiocentric, nonsuppurative, mixed lymphoid inflammatory process affecting predominantly the white matter of the cerebrum, caudal brainstem, cervical spinal cord and meninges.
Dx: CSF, rule out infectious (serology/PCR)
MRI findings for the disseminated form include multiple hyperintensities on T2-weighted and T2 fluid-attenuated inversion recovery sequences scattered throughout the central nervous system white matter
Tx: pred mmonotherapy vs combined cytosine arabinoside and cyclosporine
poor prognosis, 1 to >1215 days
unknown etiopathogenesis
List some forms of infectious meningitis
Viral
- Canine distemper (guarded prognosis)
- FIP
Protozoal
- Toxoplasma gondii
- Neospora caninum
Bacterial
- Staph
- Pasteurella
- E.Coli
- Actinomyces
syndromes occur with both T. gondii and N. caninum infection:
Toxo: carnivorous ingestion of encysted bradyzoites or tachyzoites
Meningoencephalomyelitis: Multifocal neurologic signs reflect the location cerebellitis has been reported in older dogs
Myositis-polyradiculoneuritis: In juvenile dogs younger than 6 months of age, myositis, progressive polyradiculoneuritis of the pelvic limbs,
dog is the definitive host for N. caninum
What IgM antibody titres are suggestive of disease of toxo and neo?
serial increases support active infection
IgG indicate exposure only
Greater than 1:64
Treat with clindamycin
What are three potential sources of bacterial meningitis?
Haematogenous spread
Direct inoculation (wounds/needles)
Direct extension from other structures of the head
Use an ABx which effectively crosses the BBB (metro, enro, chloramphenicol etc) for 1-4 months post resolution
Dx distemper
virus infects all epithelial tissues, along with the CNS
antemortem
Several assays with variable sensitivities may be used for the antemortem diagnosis of canine distemper virus (Table 30.2). Immunohistochemical testing for canine distemper virus antigen on biopsy specimens of nasal mucosa, foot pad epithelium, and haired skin of the dorsal neck has been reported to be a sensitive and specific test.65 Similarly, reverse transcription PCRs (RT-PCRs) applied to RNA extracted from whole blood, urine, cerebrospinal fluid, tonsillar, or conjunctival specimens are sensitive and specific assays
Grey matter > white matter > Necrotizing meningoencephalitis
What breeds are overrepresented for discospondylitis?
Great Dane, Labs, Rottweilers, GSD, Doberman, Eng Bulldog
Female GSD overrepresented for fungal disco
What are some speculated caused of vertebral endplate infection in the development of disco?
“dead-end” capillary loop trapping circulating bacteria
Microtrauma associated neovascularisation of the adjacent IVD
most common patholgens isolated from disco lesions?
Staph
E.Coli
Brucella canis (zoonotic)
Strep
Klebsiella
Pseudomonas
Proteus
Actinomyces
Regarding disco, what is the percentage diagnosis from blood and urine culture as apposed to percutaneous intervertebral disc aspiration?
Blood and urine culture 40%
Disc aspiration 60%
What is a good emperic option for treating disco?
carprofen (2.2 mg/kg PO q12-24h
First-generation cephalosporins or amoxiclav
Good penetration of bone!
17% of staph spp are resistant to first-gen cephalosporins….
Treat for 8 weeks
pain and paraspinal hyperesthesia are reduced markedly within 3 to 7 days
disko px
Dx: Radiographic features of discospondylitis progress from initial narrowing of the intervertebral disc space to focal lysis of the vertebral end plates, and, finally, to marked lysis, sclerosis, and spondylosis
prognosis is fair to good for dogs with uncomplicated discospondylitis. Recrudescence of disease
What are some hypotheses for the entry of the fibrocartilaginous into the vessel in FCE?
Direct penetration of the fibrocartilage from the nucleus pulposus disc into the vessel
Remnant vessel within the nucleus pulposus
Herniation of a portion of the nucleus pulposus into the bone marrow and subsequent retrograde movement into the internal vertebral venous plexus
Neovascularisation of the degenerated intervertebral disc
How can MRI imaging help to prognosticate in FCE lesions?
hyperintense lesion on T2-weighted images
Leison-to-vertebral length ratios greater than 2, 60% unsuccessful outcome
Lesion-to-vertebral length ratio less than 2, 100% successful outcome
dx FCE
presumptive diagnosis is based on MRI, cerebrospinal fluid findings, and exclusion of alternative differentials.
11 of 52 dogs (21%) had no detectable MRI
A Review of Fibrocartilaginous Embolic Myelopathy and Different Types of Peracute Non-Compressive Intervertebral Disk Extrusions in Dogs and Cats
Luisa De Risio 2015
FCEM recovery of VMF > reported as 6 days
intradural/intramedullary intervertebral disk extrusion (IIVDE).
ANNPE and IIVDE most commonly occur in the intervertebral disk spaces between T12 and L2, whereas FCEM has not such site predilection. In cats, FCEM occurs more frequently in the cervical spinal cord
ANNPE and IIVDE, the affected intervertebral disk space is often narrowed and the focal area of intramedullary hyperintensity T2W
Prognostic factors include degree of neurological dysfunction (particularly loss of nociception) and disease-specific MRI variables.
FCEM include a focal, relatively sharply demarcated intramedullary, and often lateralized lesion (edematous infarcted tissue), predominantly involving the gray matter, >1 vertebral length
MRI performed 24–72 h after onset of neurological signs may reveal no intraparenchymal signal intensity changes in dogs with FCEM
ANNPE generally less than one vertebral length
Px: 43 dogs with FCEM loss of nociception, 42 dogs have been euthanized generally within 1 week of disease onset and 1 only has been reported to recover. There is limited information on ANNPE or IIVDE
All dogs with a neurological score of 5 had an unsuccessful outcome. Of dogs with a neurological score of 4 (para or tetra plegia with preserved nociception), 6/20 (30%) dogs with FCEM and 6/13 (46%) dogs with ANNPE had an unsuccessful outcome.
Clinical features, comparative imaging findings, treatment, and
outcome in dogs with discospondylitis: A multi-institutional
retrospective study
Cassie Van Hoof 2023
Three hundred eighty-six dogs.
Methods: Multi-institutional retrospective study.
L7-S1 (97/386 dogs) was
the most common site. Staphylococcus species (23/38 positive blood cultures) were prevalent.
(73.6%) were treated with medical
management, while 40 of 386 dogs (10.4%) also underwent surgical
Follow-up status was
reported in 101/386 cases (26.2%). During known follow-up, 12 of
101 dogs (11.9%) had a clinical relapse while an additional 12 dogs
(11.9%) developed progressive neurological deterioration
Computed tomography features of discospondylitis in dogs
Sergio A. Gomes1
We determined that bilateral endplate erosion
and periosteal proliferation were very common in dogs with discospondylitis. Careful
evaluation of CT in all 3 planes (dorsal, sagittal, transverse) is necessary to identify an
affected IVDS. These described CT features can aid in the diagnosis of discospondylitis
in dogs but equivocal cases might still require MRI.
Clinical features, treatment and
outcome of discospondylitis in cats
Sergio A Gomes1
Feline discospondylitis is uncommon and no obvious signalment predisposition
was found in this study. Spinal hyperaesthesia was universally present, with neurological dysfunction also highly
prevalent. Bacterial culture was unrewarding in most cases. Amoxicillin–clavulanic acid or cephalosporins are
reasonable choices for first-line antibiotics. Prognosis was favourable, with no long-term evidence of recurrence in
cats on sustained antibiotic therapy, for a mean duration of 3 months.
