Small Animal Neuroradiology: The Spine
Lecture 1 – Radiography and Contrast Techniques,
Anomalous Diseases
VCA 341 Fall 2011
Andrea Matthews, DVM, Dip ACVR
Assistant Professor of Radiology
Normal Anatomy
Canine and feline vertebral formulas
Cervical
7
Thoracic
13
Lumbar
7
Sacral
3 (fused)
Caudal
Variable
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Normal Anatomy – Cervical
C1 (or “atlas”)
 Central arch and two wide horizontal wings
perforated by transverse foramina
C2 (or “axis”)
 Long, thin spinous process which overlaps the
dorsal arch of C1
 Odontoid process (dens)
C6
 Expanded transverse process ventrally
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Cervical Spine
C1
C2
C3
C5
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Cervical Spine
atlas
C1
axis
C2
C3
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C5
TUSCVM
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Normal Anatomy – Thoracic
Rib heads articulate with cranial aspect of
corresponding vertebral bodies
Spinous processes change direction from caudal
angulation to cranial angulation at the anticlinal
vertebra (usually T11)
Accessory processes on last 4-5 thoracic vertebrae
T10-11 intervertebral disc space is normally narrow
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Thoracic Spine
Anticlinal vertebra
Anticlinal disc
space is narrow
normally
T11
Proximal ribs
T10
TUSCVM
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Normal Anatomy - Lumbar
Lumbar vertebral bodies are longer than
thoracic vertebrae
 Especially in cats.
Transverse processes are angled cranially,
laterally and somewhat ventrally
}
Accessory processes (present on the first four
vertebrae) can be especially large in cats
Do not mistake
for
mineralized
intervertebral
disc material!
“Fuzzy” ventral margin of L3 and L4
 Due to attachment of the diaphragmatic crura
(especially in large dogs).
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Lumbar Spine
TUSCVM
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Thoracic Spine
Accessory process
TUSCVM
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Lumbar Spine
Attachment for diaphragmatic crus
L3
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L4
TUSCVM
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Sacral / Caudal Vertebra
Sacrum
 Lumbosacral angulation can vary significantly
between individuals
•
Changes with degree of flexion or extension
Caudal Vertebra
 Formerly known as coccygeal vertebrae
 Vary in number
 Hemal arches ventrally
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Sacral / Caudal Vertebra
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Lumbosacral Junction
Ilial wings
Articular facet joint
TUSCVM
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Lumbosacral Junction
Margins of the sacrum
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TUCSVM
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Typical Vertebra
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Ligamentous Structures
Konig and Liebich, Veterinary Anatomy of Domestic Animals, 3 rd Ed
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Survey Radiography
Lateral and ventrodorsal views
Adequate relaxation is required for good positioning
 General anesthesia preferred
•
•
Exception: Suspected fracture and/or luxation
Can obtain lateral and horizontal beam
Collimation to improve quality
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Survey Radiography
Lateral cervical
radiograph
Ventrodorsal cervical
radiograph
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Survey Radiography
Lateral thoracic radiograph
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Survey Radiography
Beware of “pseudonarrowing” of disc spaces
 Artifactual narrowing due to divergence of x-rays
Kishigami, Y.et al. Vet Radiol Ultrasound 41, 9–18
(2000).
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Pseudonarrowing
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Radiography and Contrast
Techniques
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Myelography
Introduction of contrast into subarachnoid space
 Water soluble, iodinated, non-ionic contrast media
Sites of injection
 Cisterna magna
• More likely to seizure
• Difficult to get flow caudally in some cases
 Lumbar (L5-6, L4-5)
• Possible epidural leakage
• More difficult technically
• Fewer complications
• Better flow of contrast typically
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Myelography
Site for cervical injection
Site for lumbar injection
Diaz, F. In Practice 27, 502-510 (2005).
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Myelography
 Contraindications
Indications
 Neurologic signs with no
lesion on survey rads
 Multiple lesions seen on
survey rads
 Single lesion seen on survey
rads not consistent with
clinical signs
 Abnormality on survey rads
which needs further
characterization
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 Inflammatory disease
(meningitis)
 Bleeding diatheses
 Evidence of vertebral
instability (could increase
spinal cord damage)
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Normal Myelogram
Courtesy Dr. L. Pack
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Extradural Lesion
Extruded intervertebral disc material
L3
L3
L4
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Intradural/Extramedullary Lesion
Golf tee sign
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Intramedullary Lesion
Widening of spinal cord due to spinal
cord tumor (glioma)
Courtesy Dr. L. Pack
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Anomalous Diseases
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Hemivertebra
Failure of vertebral body to develop fully
 Persistence of sagittal membrane (notochord)
Most commonly in thoracic spine
 May have focal kyphosis
Often incidental finding
Bulldogs, Boston terrier and pugs (“screw-tailed” breeds)
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Hemivertebra
Butterfly vertebra
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TUCSVM
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Block Vertebra
Fusion of two or more adjacent vertebrae
 Involve bodies, laminae and pedicles or entire
vertebrae
 Incomplete development of intervertebral disc
Can occur at any location in spine
Incidental
 Differentiated from healing fractures, luxations,
discospondylitis
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Block Vertebra
TUCSVM
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Transitional Vertebra
Vertebra at the junction between two spinal regions
that assumes the characteristics of both regions
 Thoracolumbar, lumbosacral and sacrocaudal
junctions
Usually incidental findings
 Important when identifying surgical site
 Make positioning of VD pelvis difficult
 Can be associated with lumbosacral instability
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Transitional Vertebra
Sacralization of L7
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Spina Bifida
Part of general defect called Spinal Dysraphism

Failure of neural arch to close during
embryogenesis
Two types
1. Spina bifida occulta
•
•
No spinal cord or meningeal involvement
No clinical signs typically
2. Spina bifida manifesta
•
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Protrusion of the meninges (meningocele) or meninges
and spinal cord (meningomyelocele)
Associated clinical signs
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Anomalous Diseases
 Common in screw-tailed breeds
• Bulldogs, Boston Terriers, Pugs,
Manx cats
Failure of fusion of spinous processes
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Other Anomalies
Scoliosis
 Lateral bowing as seen on a VD
or DV view
Lordosis
 Ventral bowing as seen on a
lateral view
Kyphosis
 Dorsal bowing as seen on a
lateral view
Scoliosis (from Radiographic Interpretation
for the Small Animal Clinician 2nd Ed)
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The End
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