Chapter 15 CT/MRI Vertebral column 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 spinal cord segments, but they are located at C6-C7 vertebral column level
Where is the lumbar intumescence?
L4-S3 spinal cord segments
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
Why lateral disc extrusion is more common in the cervical region?
The dorsal longitudinal ligament, which lies on the floor of the vertebral canal, is wider and thicker in the cervical region compared to thoracolumbar.
Where are located the intercapital ligaments? ONE or MORE correct
a. Dorsal to the dorsal longitudinal ligament
b. Ventral to the dorsla longitudinal ligament
c. From Le-to-Rt rib heads between T2 and T11.
D. From Le-to-Rt rib heads between T2 and T12.
b and c
Which ligament is responsible in some pathological lesions to have bilobed shape on cross-sectional imaging?
a. Inteararcuate ligaments
b. Dorsal longitudinal ligament
c. Ventral longitudinal ligament
d. Meningovertebral ligament
d.
forms a continuous attachment between the ventral surface of the dura mater and dorsal longitudinal ligament.
Which layer of the meninges is highly vascular?
Pia mater
CSF apart from the subarachnoid space, it is also found in the central canal of the spinal cord, which communicates with the _______ _______ cranially and terminates caudally blindly at the conus
medullaris or in some subjects is continuous with the lumbar subarachnoid space.
4th ventricle
Which structure is indicated by the white arrowhead?
Dural or thecal sac
The hyperintense cerebrospinal fluid (CSF) within the dural sac is indicated by (asterisk). The extremity of the spinal cord and intradural nerve roots are visible (black arrow) in the dural sac, which forms a hypointense rim around the CSF (white arrowhead). The epidural fat around the dural sac (e) is less hyperintense than CSF. Extradural nerve roots are visible as focal
hypointensities (white arrows) in the epidural space
How does the cortical bone appears in all MRI sequences?
a. Isointense
b. Hypointense
c. Hyperintense
d. No distinct
b
The spinal cord, nerve roots, and bone marrow are
isointense or slightly hypointense to the intervertebral discs.
Which MRI sequences have a natural myelographic effect?
a. T2W
b. single-shot fast spin echo (SSFSE)
c. half-Fourier acquisition
single-shot turbo spin-echo (HASTE)
d. FLAIR
b and c
which part of the IVD has more collagen and less ground substance?
Annulus fibrosus
- The ground substance is composed
of hyaluronic acid and glycosaminoglycans that hold water.
- Water, bound to large proteoglycan molecules, is the principal component of the nucleus pulposus (80%-88%).
- The normally very bright signal of the nucleus pulposus on T2W images is caused by the
long T2 relaxation time of water.
What is false about IVDD?
a. Hansen type I IVDD (extrusion) is more common in chondrodystrophic dogs.
b. IVD extrusion is observed in mid age animals, with a peak incidence at 6-7 years old.
c. Hansen type II IVDD is an annular protrusion commonly associated with fibroid degeneration.
d. Type II herniation is usually observed in nonchondrodystrophic dogs, later in life,
approximately 8 to 10 years old.
b. IVD extrusion is observed in younger animals (2- 7 years old, with a peak incidence at 4-5 years old)
Which % of dachshunds have transitional anomalies?
a. 20%
b. 5%
c. 15.8%
d 10%
d
3 imaging findings for diagnosis of degenerated IVDD from MRI
- Extradural compression of the spinal cord centered at the level of an intervertebral disc
- Degeneration of the disc
- Narrowing of the intervertebral disc space: This
Cervical IVDD accounts apprximately __-___% in dogs. IVD extrusion is common in small-breed dohs, particularly dachshunds and beagles but it is also seen in large breed dogs, particularly _______, Rottweilers, Labrador Retrievers and ______.
14-16%
German Sheperd
Dalmatians
most common sites of cervical herniation in small breed dogs? and in large breed dogs?
Small-breed dog C2-C5
Large-breed dogs C4-C5 and C6-C7.
Most common sites thoracolumbar IVDD
T12-L1
Cranial thoracic disc herniation causing spinal cord compression has been reported to be more
common in German shepherd dogs compared to other largebreed dogs, especially at T2-T5.
development of intramedullary T2 hyperintensity following disc herniation is associated with
more severe neurologic deficits at presentation. True or false?
True
- intramedullary T2 hyperintensity that exceed the length of L2 on sagittal images have been associated with a poor outcome in approximately 50% of patients. better predictor of poor outcome than loss of deep pain perception, and it is independent from the severity of neurologic signs.
VS - more recent studies (3 Tesla) did not find an association between length of T2W hyperintensity and recovery of motor function.
Degenerative lumbosacral stenosis is an abnormal narrowing of the _______ vertebral canal or intervertebral foramina, with compression of the cauda equina and/or its blood supply.
L5-S3
Findings in degenerative lumbosacral stenosis (name at least 3)
- IVD degeneration
- IVD protrusion
- bone proliferation on the vertebral endplates and articular processes
- vertebral subluxation
- hypertrophy of the articular process joint capsule and interarcuate ligament (ligamentum
flavum) - Acute lumbosacral disc extrusion is much
less common but carries an excellent postsurgical prognosis.
idiopathic lumbosacral stenosis and loss of perineural fat have been reported
in dogs with no clinical signs. True or false?
True
Most common affected sites of cervical foraminal and far lateral disc extrusion
C5-C7
In which breed is more common the cervical arachnoud diverticula? which is the typical shape of these lesions?
Rottweilers, teardrop shape
Thoracolumbar in pugs, with potential association with aplasia of the articular processes in the caudal throacic spine
Which type/types of spinal dermoid sinuses may be associated with neurologic signs?
Type IV and VI due to its relationship witht he dura mater
Can you distinct clinically and in imaging synovial cyst from ganglion cyst? Yes or No
No, the term used is articular process cyst
- Intradural/extramedullary
tumors are mostly _______ and
meningiomas. - Intramedullary neoplasms are usually of glial cell origin, such as astrocytomas or _________, but multicentric non-neural neoplasia (such as, lymphoma) or metastatic lesions (such as, hemangiosarcoma) also occur.
Nerve sheath tumours, ependymomas,
CSF apart from the subarachnoid space, it is also found in the central canal of the spinal cord, which communicates with the _______ _______ cranially and terminates caudally blindly at the conus
medullaris or in some subjects is continuous with the lumbar subarachnoid space.
4th ventricle
