Chaprter 14 Vertebrae & Myelography Flashcards
The dens originates from the intercentrum of C2 - true or false?
False; The dens originates from the intercentrum of C1, but during development, it attaches to C2 and lies within the vertebral canal of C1.
Where does the nuchal ligament attach in dogs? in cats?
Not present in cats. In dogs: spinous processes of C2 to T1-2-3, continues caudally as supraspinous lig.
which lig. is the caudal continuation of the nuchal lig.?
supraspinous
8-year-old Doberman pinscher
diagnosed with cervical spondylomyelopathy; what is this (arrow)?
lig. flavum hypertrophy
another name for lig. flavum
interarcuate lig.
what do the intercapital lig. do?
hold rib heads together from T2 to T11
why are IVDEs less common between T1 and T11?
intercapital lig
where are the intercapital lig. present?
T2 - T11
_____ is the anticlinal vertebra in most dogs;
T11; however, T10 may also be designated the anticlinal vertebra.
The intervertebral disc spaces of the cervical vertebrae become progressively_________ between C2-C3 and C6-C7.
wider
The ______________ (thoracic) intervertebral disc space is narrower than adjacent disc spaces in most dogs
T10 - T11
Block vertebrae are most common in the _________
region.
cervical
block vertebra affecting C2-C3. The intervertebral disc space appears as a thin vertical radiolucent
line. A radiolucent line is also visible dorsally at the dorsal articular process joint (arrow). These lines signify that complete fusion has not occurred in
this dog although there is still increased risk of altered loading of the intervertebral disc at C3eC4, immediately caudal to the fusion.
what shape hemivertebra is this?
butterfly
what shape hemivertebra is this?
wedge
Wedge hemivertebrae can lead to:
A: lordosis
B: kyphosis
B: kyphosis
There is an increased incidence of _______________ and _____________ that occurs in dogs with a lumbosacral transitional malformation. In cats, they have been established as a risk
factor for _______________.
dogs:
lumbosacral disc disease
nerve root compression
cats: lumbosacral stenosis
Cats with nontraumatic lumbosacral abnormalities, including absence of L7, transitional vertebra, and L7-S1 degeneration, are at increased risk for ________________.
constipation and megacolon
Spina bifida is most common in _______(dogs) and_______ (cats).
bulldogs, Manx cats
with which neural tube defects is spina bifida associated?
meningocele or meningomyelocele
Where would spina bifida tend to be more severe i.e. in which region of the spine?
lumbar;
There is rarely a neural tube defect in dogs with thoracic SB. At the LS junction, however, the morphologic derangements are often
more severe with absent spinous process, laminar defect, and neural tube defects.
Which finding is commonly present with congenital AA subluxation/luxation (as opposed to traumatic)?
With congenital malformation, the dens is often absent or incompletely ossified. There may also be deficiencies in the ligaments that support the atlantoaxial joint and prevent flexion.
Which breed(s) is (are) predisposed to AA subluxation?
toy breeds e.g. Yorkie
Which ligament is usually malformed or ruptured in AA subluxation?
transverse ligament of the atlas (covers the dens)
If AA subluxation is suspected, the neck should not be _______________ (flexed, extended) during radiography.
Flexed
Spina bifida in a dog
A. Absent spinous process
B. Nerve roots track dorsally through the defect. S Syrinx
Pre-con CT was normal (no material seen). What is the explanation for thinning of the contrast column and for the area of contrast (dotted black arrow)?
This dog had ANNPE. White arrows reveal thinning of lateral contrast columns consistent with spinal cord swelling. Dashed black arrow
points toward area of uptake by the spinal cord indicating penetration of the pia by explosive forces from herniation
of normal nucleus pulposus.
In myelography, a forked subarachnoid contrast medium is indicative of…?
A lateralized disc, this is a false intradural-
extramedually sign
Moderate epidural leakage after lumbar myelog-
raphy at L5-L6. Epidural contrast medium is recognized ventrally by the appearance of opaci ed vertebral venous sinuses (large closed arrows) and dorsally by opaci cation dorsal to the subarachnoid space (small closed arrows).
Opaci ed depressions in the vertebral bodies contain the basivertebral veins (open black arrows). Epidural contrast
medium summates with the subarachnoid space limiting interpretation.
Opacification of the central canal (arrows)
occurs when communication exists between the central canal and the subarachnoid space.
If AA subluxation is present,
- the axis is more ________ (dorsal/ventral)
- there is _________ (increased/decreased) overlap between C1 and C2
dorsal
decreased
What is the key to spotting AA subluxation?
Looking at the alignment of the C1 and C2 dorsal lamina
How many centers of ossification fuse to form the atlas? By when is this
process normally complete?
3 centre
4 months of age
What is a clinically relevant complication of incomplete C1 ossification?
Incomplete ossification can lead to osseous defects at the junction of the centers of ossification and may lead to instability
and atlantoaxial subluxation. Surgical stabilization may be necessary in dogs with clinical signs.
Which type of Wobblers do Great Danes get? what age group is affected usually?
Young Great Danes, osseous - articular process malformation and hyperostosis.
Which type of Wobblers do Dobermans get? what age group is affected usually?
Disc-associated, mature. ligamentous hypertrophy and degenerative IVDD
Osseous wobblers in a great dane
What is the 3 compartment theory on vertebral fractures and sub/luxations?
If more than 1 compartment is affected, it is unstable.
Whats the dorsal vertebral compartment?
- spinous process, supraspinous and interspinous ligaments
- vertebral laminae
- articular processes
- vertebral pedicles
- ligamentum flavum.
Whats the middle vertebral compartment?
- dorsal longitudinal ligament
- dorsal annulus fibrosus
- dorsal portion of the vertebral body.
Whats the ventral vertebral compartment?
ventral longitudinal ligament, ventral annulus, and ventral cortex of the vertebral bodies
Which disc spaces are usually narrower than adjacent disc spaces?
T10-11
L5-L6
Which parasite can induce spondylitis?
Spirocerca lupi
Which radiographic/imaging changes could Spirocercosis induce?
Spondylitis
Esophageal granulomas/fibroblastic nodules > can malignantly transform into sarcoma
Aortic aneurysms and mineralisation
What is spondylitis and what are common causes?
Inflammation of the vertebral body, usually caused by:
- Microbial infection
- Plant awn migration
- Spirocercosis
- Extension from paraspinal abscesses
Around which area is spondylitis caused by spirocercosis most common?
T8-T11
In which part of the vertebra will you have osseous changes due to spirocercosis?
ventral aspect of the body (not endplates), from T8-T11.
This can look similar to periosteal reactions from metastatic neoplasia.
With which condition is vertebral physitis associated with in young dogs?
PSS
What is specific about vertebral vascularisation that may predispose it to hematogenously introduced infection?
the capillary system has slower flow at the physes
Spirocerca lupi infection; thoracic spondylitis and esophageal granuloma.
Spondylitis due to grass seed migration
What is discospondylitis?
Inflammation of the intervertebral disc and adjacent endplates
Where are Sharpey’s fibers located?
They extend from the annulus fibrosus into the cortex of the vertebra.
What is the accepted theory of the initial trigger of spondylosis deformans?
Disruption of Sharpey’s fibers (collagen attachments between annulus fibrosus and vertebral cortex)
Nerve root compression from spondylosis is rare except in ____________________.
lumbosacral instability where foraminal impingement results from dorsal extension of the enthesophytes
What is the terminal part of the spinal cord called?
Conus medullaris
Where does the spinal cord end in dogs?
L6-L7
Where does the spinal cord end in cats?
L7
What is the name for the collection of nerves that are caudal to the end of the spinal cord?
Cauda equina
Conus medullaris is the end of the spinal cord, cauda equina is beyond that.
DISH is just advanced spondylosis deformans (of 4 or more contiguous vertebrae) - true or false?
False, and anyway it’s 3 or more.
What are the 7 criteria of DISH? How many should be present to qualify for this diagnosis?
4 of the following 7:
DEBOSS
1. Disc non-degenerated and disc space width preservation
2. Enthesopathies
3. Bridging Ventrolaterally of 3+ contiguous vertebrae
4. Osteoarthritis of dorsal intervertebral joints
5. Spinous process pseudoarthrosis
6. Sacroiliac ankylosis, osteophytosis, sclerosis
7. Symphisis pubis ankylosis
Which vertebral change occurs with MPS VI?
epiphyseal dysplasia, which manifests as remodeling, spondylosis, change of the vertebral shape, and an abnormal dens.
In the appendicular skeleton, epiphyseal dysplasia, with
- Conchae are abnormal
- Coxofemoral subluxation
Lateral radiograph of a cat with nutritional secondary hyper-
parathyroidism. There is marked generalized osteopenia with reduction in
bone opacity. The normal high contrast between bone and soft tissue has
been lost.
What is the full and what is the regional dose for CT myelography?
0.45 ml/kg
0.3 ml/kg
These are just guidelines, you need to give a sufficient amount (might be more). For CT, it can be diluted.
Where is lumbar puncture performed?
L5-6, L6-7
basilar artery
This is a cat with spinal cord swelling - true or false?
False; In the cat, the spinal cord is relatively wide and occupies a large percentage of the vertebral canal. As a result, the subarachnoid space is thin and conforms closely to the margins of the vertebral canal; this can give a false impression of cord swelling
Arachnoid diverticulae are cyst-like or trily cystic?
Cyst-like, as they are not lined with epithelium.
Arachnoid cysts are classifed as:
A) intramedullary
B) intradural (extramed)
C) extradural
B) intradural (extramed)
Recognition of the intradural-
extramedullary location of arachnoid cysts is important so
that they can be differentiated from nonsurgical intramedullary
lesions such as hydromyelia or syringomyelia. The intradural-
extramedullary sign in this instance differs from that of a
mass lesion (e.g., neuro broma) in which a lling defect is
present as well as subarachnoid dilation. Arachnoid diverticula
that arise from causes other than previous trauma or surgery are
commonly located in the dorsal aspect of the cervical sub-
arachnoid space.
Non-traumatic/iatrogenic arachnoid cysts are commonly located in which aspect (lateral, dorsal, ventral) of the (cervical, thoracic, lumbar) canal?
dorsal, cervical
Subarachnoid diverticulum
How do the intercapital ligaments contribute to vertebral stability in dogs?
a) They connect the spinous processes from T1 to T11
b) They reduce disc herniation between T1 and T11 by buttressing the annulus
c) They stabilize the atlantoaxial joint alongside the dens
d) They bridge the vertebral arches dorsally with elastic fibers
b
What type of joints are formed by the articular processes of the lamina?
a) Cartilaginous
b) Synovial (diarthrodial)
c) Fibrous
d) Immovable
b
How many vertebrae are fused to form the sacrum?
a) Two
b) Three
c) Four
d) Five
b
What mainly stabilizes the atlantoaxial joint to prevent spinal cord damage?
a) Nuchal ligament
b) Transverse ligament of the atlas
c) Supraspinous ligament
d) Intercapital ligaments
b
What is the role of the intervertebral disc?
a) Stabilize the spinous processes
b) Act as a hydraulic shock absorber
c) Protect the vertebral arteries
d) Form synovial joints
b
Which of the following accurately describes the relationship between the dens and C1?
a) The dens originates from C2 and remains independent of C1
b) The dens is a projection of C1 that articulates with C2
c) The dens originates from the intercentrum of C1 and attaches to C2 during development
d) The dens is a transverse process of C1 that stabilizes C2
c
How do the intercapital ligaments contribute to vertebral stability in dogs?
a) They connect the spinous processes from T1 to T11
b) They reduce disc herniation between T1 and T11 by buttressing the annulus
c) They stabilize the atlantoaxial joint alongside the dens
d) They bridge the vertebral arches dorsally with elastic fibers
b
How does the dorsal longitudinal ligament differ from the ventral longitudinal ligament?
a) It lies ventral to the vertebral bodies and is smaller
b) It extends from the dens to the sacrum within the vertebral canal
c) It contains yellow elastic fibers and bridges vertebral arches
d) It is absent in cats but present in dogs
b
The ligament absent in cats is nuchal
What is the vertebral formula for a cat?
a) C7 T13 L7 S3 Cd6-Cd23
b) C7 T13 L7 S3 Cd18-Cd21
c) C7 T12 L6 S3 Cd18-Cd21
d) C7 T13 L6 S3 Cd6-Cd23
b
Dog: C7 T13 L7 S3 Cd6-Cd23
How do the articular processes of adjacent vertebrae overlap?
a) Cranial process dorsal to caudal process
b) Caudal process ventral to cranial process
c) Cranial process ventral to caudal process
d) No overlap occurs
c
How is the dens best visualized radiographically?
a) True lateral projection
b) Ventrodorsal projection
c) Lateral view with slight axial rotation
d) Oblique projection with full rotation
c
What indicates a normal relationship between C1 and C2 on a lateral projection?
a) Widely separated spinous processes
b) Closely spaced spinous processes and parallel dorsal laminae
c) Overlapping transverse processes
d) Divergent dorsal laminae
b
Which vertebra is characterized by a large transverse process?
a) C2
b) C6
c) T1
d) L7
b
Which thoracic vertebra is typically the anticlinal vertebra in dogs?
a) T9
b) T10
c) T11
d) T12
c
- T11 is the anticlinal vertebra in most dogs; however, T10 may also be designated the anticlinal vertebra.
- The T10eT11 intervertebral disc space is narrower than adjacent disc spaces in most dogs.
Why might the ventral bodies of L3 and L4 appear indistinct in large dogs?
a) Narrow intervertebral disc spaces
b) Entheses for diaphragmatic crura
c) Overlap of articular processes
d) Fusion with the sacrum
b
What distinguishes a hemivertebra from a compression fracture radiographically?
a) Disrupted cortex
b) Smoothly marginated cortex
c) Irregular endplates
d) Widened disc space
b
What is a key radiographic clue for hemivertebrae on a VD projection?
a) Increased disc spacing
b) Decreased rib spacing
c) Split spinous process
d) Asymmetry of laminae
b
In atlantoaxial subluxation, what causes extradural spinal cord compression?
a) Ventral displacement of C1
b) Dorsal displacement of C2
c) Fusion of C1 and C2
d) Hypertrophy of C1 laminae
b
Which ligament’s rupture frequently leads to atlantoaxial subluxation?
a) Dorsal atlantoaxial ligament
b) Apical ligament
c) Transverse ligament of the atlas
d) Alar ligament
c
Which breed is most predisposed to congenital atlantoaxial subluxation?
a) Bulldog
b) Great Dane
c) Yorkshire terrier
d) Doberman pinscher
c
What abnormality is NOT directly visible on radiography?
a) Vertebral canal stenosis
b) Vertebral tipping
c) Ligamentum flavum hypertrophy
d) Articular process remodeling
c,
Disc degeneration/prolapse
Extradural spinal cord compression
Ligamentum flavum, interarcuate ligament, or joint
capsule hypertrophy
Which modality is required to identify hypertrophy of the interarcuate ligament or joint capsule?
a) Radiography
b) Myelography
c) Computed Tomography
d) Magnetic Resonance
d.
What is the most reliable radiographic sign of disc herniation in radiography?
a) Small intervertebral foramen
b) Narrowing of the disc space
c) Mineralized disc material
d) Increased foraminal opacity
b
What is a proposed cause of vertebral physitis in young dogs?
a) Trauma
b) Hematogenous sepsis
c) Disc degeneration
d) Parasite migration
b
What minimum bone loss is required for radiographic detection of metastatic lesions?
a) 20-30%
b) 30-60%
c) 50-75%
d) 75-90%
c
What vertebral change is characteristic of mucopolysaccharidosis type VI in cats?
a) Osteopenia
b) Epiphyseal dysplasia
c) Pathologic fracture
d) Coarse trabecular pattern
b
