Ch 15 CT/MRI Spinal Cord Flashcards
Where is the meningovertebral ligament located? When do we ‘see’ it, or when is it significant?
Between the dura (“meningo”) and the dorsal longitudinal ligament/dorsal vertebrae (“vertebral”). In HNPE, it is the ligament (when intact) that gives the material its bilobed shape.
Which ligament is responsible for the bilobed appearance of extruded material in HNPE?
meningovertebral
In smaller dogs, the conus medullaris is more caudal/cranial than in large dogs.
Caudal - smaller skeleton, but spinal cord not proprortionally smaller
Where is the cervical intumescence?
C6-T2
Where is the lumbar intumescence?
L4-S3
Dachshunds and chondrodystrophic breeds have a (higher/lower) spinal cord:vertebral canal compared to non-chondro dogs.
higher; thicker spinal cord
arrange from inner to outer:
- dura mater
- subarachnoid
- pia mater
- epidural
- spinal cord
- arachnoid
- subdural
spinal cord
pia
subarachnoid space
arachnoid
subdural (potential space)
dura
epidural
The central canal communicates cranially with _____________ and caudally _______________.
Cranially: the 4th ventricle
Caudally: ends in the conus medullaris or may communicate with the lumbar subarachnoid space/CSF
The spinal subarachnoid space is cranially continuous with _________________, and caudally ends ________________.
Cranially: intracranial SAS
Caudally: near LS junction, within the dural sac
Myelography is performed by injecting contrast in the
A. Epidural space
B. Subdural space
C. Subarachnoid space
C. Subarachnoid space
Epidural is for regional anaesthesia.
Subdural is just a potential space, relevant for e.g. subdural (banana-shaped) brain haemorrhage.
Where is the lumbar intumescence, at which lumber vertebral level?
Around L4-L5
Where is the cervical intumescence, at which vertebral level?
C6-C6
arrow
basivertebral venous canal. Commonly malformed in bulldogs.
What is the arrow pointing to i.e. what does the T1w hypointense ring represent ?
Combination of dura and chemical shift artifact
What is the arrow pointing to i.e. what does the T1w hyerintense line represent?
Synovial fluid in the articular process joints; their cortices are the adjacent T2w hypointense lines
which type ivdd (hansen 1 or 2) is more common in chondrodystrophic dogs?
1
What is a schmorl’s node?
intravertebral disc extrusion
In a Hansen 2 / protrusion, there is partial rupture of the dorsal AF - true or false?
True.
focal hyperattenuation dorsal to the vertebral body (white arrow in CT image) that is created by the bony bridge covering a portion of the dorsal foramina.
not to be confused with mineralization of the dorsal longitudinal ligament and herniated disc material.
Which breed might be more prone to extensive epidural haemorrhage following IVDE?
Frenchies obviously
Does extradural compressive material in IVDD (disc/haemorrhage) contrast enhance?
Yes, commonly, about 50% of the time.
How often is their meningeal enhancement adjacent to an IVDE?
about 40% of patients have this
What are the differentials (histopath-wise) for T2w/STIR hyperintensities (but T1w hypointensities) of the the paraspinal muscles in the area of an IVDE?
What about T2w/T1w hyperintensities of paraspinal musculature?
T2w/STIR hyper: muscle ber degeneration, edema, inflammation,
and necrosis
T2w/T1w hyper: myosteatosis (pathological fatty infiltration), probably unrelated, no prognostic indicator known.
IVDE, enhancing material
Which cervical IVDE sites are more common in small breed vs. large breed dogs?
small (cranial) - C2-C3, C3-4, C4-C5
large (caudal) - C4-C5, C6-C7
Cervical IVDE volume of material is usually more/less compared to thoracolumbar IVDE? why?
Less, the cervical dorsal longitudinal ligament is larger.
Cervical IVDE, the material is usually located where in the vertebral canal (dorsal, lateral, ventral)?
Dorsolateral, between dorsal longitudinal lig. and the venous sinus, therefore near the foramina/nerve root.
The epidural space is larger in the cervical (compared to TL) area in _______ dogs, but not in __________ dogs.
In most dogs, the cervical epidural space larger than TL.
In Frenchies, it could be the opposite, smaller cervical epidural space, larger TL.
Where is the most commonn IVDE in dogs?
T12-T13, T13-L1
In which breeds are cranial thoracic IVDEs more common?
GSD, so definitely need to include this part of the spine if they have a a T3-L3 myelopathy
The degree of spinal cord compression from an IVDE (determined by MRI) correlates / does not correlate with the neurological grade.
does not correlate; the length of spinal cord compression does, but neither correlate to the outcome anyway.
The length of spinal cord compression from IVDE correlates to the neurological grade - true or false?
true, doesn’t predict outcome though.
Outcome of an IVDE is correlated with
A) degree of spinal cord compression
B) length of spinal cord compression
C) both
D) neither
Neither. Length correlates to neurological grade.
Does the T2w intramedullary hyperintensity correlate to neurological grade or outcome?
Some studies suggest yes, but others no (to outcome, none to neurological grade).
Acute LS is very rare but carries a poor prognosis - true or false?
False, it is rare, but it has an excellent post-surgical prognosis.
Which of these late post-surgical (dorsal laminectomy for LS stenosis) changes are common?
A. ongoing nerve compression
B. enhancement of the L7 nerves
C. enhancement of the lumbosacral intervertebral joints
D. enhancement of the paraspinal soft tissues
E. all of the above
E. all of the above
What is the most common cervical site of foraminal disc extrusion?
caudally - C5-C6 and C6-C7
Differences between ANNPE and FCE
ANNPE
- Disc extrusion, so ± annular cleft, extradural material, narrowed IVD space; meningeal enhancement,
- intramedullary changes are primarily white matter, more peripheral, and over the IVD space.
- short, oblique.
- might enhance,
FCE
- normal disc.
- grey matter, overlying vertebral body. linear
- potentially longer.
- does not enhance.
What’s the most common ANNPE location in dogs vs. cats?
dogs, similar area as normal IVDE; T12-13, T13-L1
cats: L3-4, L5-6
What are prognostic indicators for dogs with ANNPE? How many have an unsuccessful outcome?
1/3 have unsuccessful outcome.
Prognostic indicators:
1. neurological grade at presentation
2. % cross sectional area of T2w intramedullary change
3. presence of haemorrhage
Most common HNPE area?
Cervical C3-C6
HNPE material on FLAIR is typically?
hyperintense, but can suppress.
HNPE
Regarding IVDEs, the ‘Y-sign’ and ‘beak sign’ indicate which type of IVDE?
Intradural (subdural, actually) extramedullary
Cervical spondylomyelopathy - MRI findings
- Disc protrusion
- Process hypertrophy
- Capsular (art. process) thickening
- Lig. flavum and dorsal longitudinal hypertrophy
- OA of the art. process joints.
- Stenosis
- Cysts (synovial)
Which signalment is predisposed to the disc-associated Wobbler’s?
old Dobermans
Which signalment is predisposed to the osseous-associated Wobbler’s?
Younger large-breed dogs - Great Dane, Bernese, GSD, Doberman
Differentials for T2w hyperintensities of white matter vs. grey matter
Grey: Edema, loss of neurons, gliosis
White: Edema, Wallerian degeneration, demyelination;
when combined with T1w hypointensity: necrosis, myelomalacia, spongiform changes.
marked hypertrophy of articular processes in a Great Dane with osseous cervical spondylomyelopathy
In Great Danes with osseous cervical spondylomyelopathy, there may be a (albeit weak) correlation between neurological grade and which MRI finding(s)?
- number of sites
- degree of spinal cord compression
- presence of T2w intramedullary hyperintensity
dog with wobbler’s; what could this lesion in a T2w transverse be?
it’s a synovial cyst from the articular process joint just caudal to it
What is a Tarlov cyst?
extradural (dorsal) nerve root cysts, also called perineural cysts.
Have SADs been reported in cats?
Yes
Spinal arachnoid diverticula are in which space, between which 2 layers?
subarachnoid, between pia mater and arachnoid
Etiology of SAD
Congenital (often)
Acquired - trauma, IVDD, arachnoiditis
Most common location of SAD
cranial cervical and caudal thoracic
Predisposed breeds for SAD
Rottweilers for (cranial) cervical SADs
Pugs for (caudal) thoracic SADs, also a familial cervical form
Which other finding is common in pugs with caudal thoracic SADs?
Aplasia of the caudal articular processes
Aplasia of the caudal articular process occurs with which condition in pugs?
SAD in the caudal thoracic spine
In pugs with SADs and concurrent aplasia of the articular process - is it the cranial or the caudal process that is aplastic?
Caudal
What intramedullary change might you get adjacent to an SAD?
- edema, from pulsating CSF (repeated concussion)
- syrinx formation, altered CSF flow
Embryologically, why do epi/dermoid cysts and sinuses form?
Failure of the surface ectoderm (future skin) to separate from the neuroectoderm (future nervous system)
What’s the difference between epi/dermoid cysts and sinuses?
Sinuses have an opening to the (midline) skin, while cysts don’t.
How does an epidermoid cyst (or sinus) differ from a dermoid cyst (or sinus)?
Epidermoid - lined with stratified epithelium, contains keratin squames and some inflammatory cells.
Dermoid - contains other skin components: sweat glands, sebaceous glands and hair follicles
How are epi/dermoid sinuses classifed? Which types may be associated with neurological signs?
By depth of sinus; Types 4 and 6.
In an abscessated epi/dermoid sinus, what would be the expected T1/T2w intensities?
centrally T2w hyper, T1w hypo
capsule T2w/T1w hypo
What finding (regarding the dura) could you find in Type IV and VI epi/dermoid sinuses?
Tenting of the dura, causing a triangular shape of the CSF/subarachnoid space; this is due to where the tract attaches to the dura and pulls it.
Dermoid sinus and meningocoele
What’s the difference between a meningocoele and a meningomyelocoele?
SAD with intramedullary edema
What 2 types of articular process cysts are there?
- outpouching of the joint due to a weak capsule, hence lined with synovial epiothelium; termed, synovial cyst.
- mucinous degeneration of the periarticular tissue, not lined with epithelium; termed ‘ganglion cysts’
they look the same, and have the same effects clinically, so are categorised under the umbrella term articular process cyst.
What’s the typical signalment and localisation of articular process cysts?
Young, giant-breed dogs - cervical
Adult/Older, large-breed dogs - TL and LS
What is a discal cyst, how common is it, and what is a more accurate term for this?
It’s a very rare condition, technically not a real cyst (hence more accurately termed discal pseudocyst) as lined with fibrous/chondral/notochordal cells, which arise from the dorsal aspect of the IVD and cause ventral/ventrolateral SCC.
What type of spinal tumors are typical for an intradural location?
nerve sheath
meningioma
Nerve sheath tumors in the spine are typically in which location?
A. extradural
B. intradural
C. intramedullary
B. intradural, like meningiomas
T1w and T2w
L articular process cyst, either synovial or ganglion cyst
What’s the most common spinal EXTRADURAL tumor in dogs?
Which tumor is common cats (same location)?
osteosarcoma
chondrosarcoma
cats: lymphosarcoma
