small animal neuroradiology: the spine lecture 1 – radiography and contrast techniques, anomalous...

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

VCA 341 – The Spine 2Matthews

Cervical 7

Thoracic 13

Lumbar 7

Sacral 3 (fused)

Caudal Variable

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

VCA 341 – The Spine

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Cervical Spine


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C1C2

C3

C5

Cervical Spine


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C1

C2

C3

C5

atlas

axis

TUSCVM

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


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T10

T11

Anticlinal vertebra

Anticlinal disc space is narrow normally

Proximal ribs

TUSCVM

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

“Fuzzy” ventral margin of L3 and L4 Due to attachment of the diaphragmatic crura

(especially in large dogs).


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}Do not mistake for mineralized intervertebraldisc material!

Lumbar Spine


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TUSCVM

Thoracic Spine


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Accessory process

TUSCVM

Lumbar Spine


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L3L4

Attachment for diaphragmatic crus

TUSCVM

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


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Ilial wings

Articular facet joint

TUSCVM

Lumbosacral Junction


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Margins of the sacrum

TUCSVM

Typical Vertebra


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Ligamentous Structures


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Konig and Liebich, Veterinary Anatomy of Domestic Animals, 3rd Ed

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


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Lateral cervicalradiograph

Ventrodorsal cervicalradiograph

Survey Radiography


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Lateral thoracic radiograph

Survey Radiography

Beware of “pseudonarrowing” of disc spaces Artifactual narrowing due to divergence of x-rays


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Kishigami, Y.et al. Vet Radiol Ultrasound 41, 9–18 (2000).

Pseudonarrowing


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Radiography and Contrast

Techniques


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


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Diaz, F. In Practice 27, 502-510 (2005).

Site for cervical injection

Site for lumbar injection

Myelography

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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Contraindications

Inflammatory disease (meningitis)

Bleeding diatheses

Evidence of vertebral instability (could increase spinal cord damage)

Normal Myelogram


Courtesy Dr. L. Pack

Extradural Lesion


L4L3

L3

Extruded intervertebral disc material

Intradural/Extramedullary Lesion


Golf tee sign

Intramedullary Lesion


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Courtesy Dr. L. Pack

Widening of spinal cord due to spinal cord tumor (glioma)

Anomalous Diseases


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

TUCSVM

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

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

Spina Bifida

Part of general defect called Spinal Dysraphism Failure of neural arch to close during

embryogenesis

Two types1. Spina bifida occulta

• No spinal cord or meningeal involvement

• No clinical signs typically

2. Spina bifida manifesta• Protrusion of the meninges (meningocele) or meninges

and spinal cord (meningomyelocele)

• Associated clinical signs VCA 341 – The Spine

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Anomalous Diseases


Common in screw-tailed breeds• Bulldogs, Boston Terriers, Pugs,

Manx cats

Failure of fusion of spinous processes

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


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Scoliosis (from Radiographic Interpretation for the Small Animal Clinician 2nd Ed)

The End


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small animal neuroradiology: the spine lecture 1 – radiography and contrast techniques, anomalous...

Documents

thoracic spine vca

cervical spine vca

narrow vca

lumbar spine vca

quality vca

survey radiography vca

typical vertebra vca

accessory process tuscvm