Small Animal Neuroradiology: The Spine Lecture 2 – Degenerative Diseases, Diseases causing...
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Transcript of Small Animal Neuroradiology: The Spine Lecture 2 – Degenerative Diseases, Diseases causing...
Small Animal Neuroradiology: The Spine
Lecture 2 – Degenerative Diseases, Diseases causing
Instability, Vertebral Injury, Infection and Neoplasia
VCA 341 Fall 2011
Andrea Matthews, DVM, Dip ACVR Assistant Professor of Radiology
Spondylosis Deformans
Bone on ventral aspect of the vertebral bodies arising from the endplates
Sometimes bridges the entire intervertebral disc space
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Spondylosis Deformans
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Courtesy Dr. L. Pack
Intervertebral Disc Disease
Anatomy
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Thrall Veterinary Diagnostic Radiology 5th Ed
Intervertebral Disc Disease
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Protrusion Herniation Extrusion
http://www.backandneckpain.ca/understanding-your-spine/499-2/
Intervertebral Disc Disease
Chondroid degeneration Chondrodystrophic breeds Dehydration and mineralization of the nucleus Hansen Type I lesions
• Extrusion of disc material into vertebral canal
• Acute – neurologic signs due to spinal cord compression
• Most commonly between T12-L2 and C2-3 in cervical region
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Intervertebral Disc Disease
Fibroid degeneration Non-chondrodystrophic breeds Fibrous metaplasia of the nucleus Hansen Type II lesions
• Stretching, partial rupture or hypertrophy of annulus with bulging into vertebral canal
• Chronic progressive course
• Can cause neurologic signs, typically chronic and progressive in nature and milder than the acute extrusion
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Intervertebral Disc Disease
High velocity, low volume disc extrusion Young to middle aged dogs No degeneration of nucleus
• Gelatinous nucleus extrudes into vertebral canal
• Usually secondary to trauma Causes concussive spinal cord injury Sometimes referred to as Type III disc extrusion
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Intervertebral Disc Disease
Clinical features Dachshunds are over-represented Less common in cats Neurologic signs are related to the site of extrusion
• UMN versus LMN
• C1-5, C6-T2, T3-L3, L4-S3 Intercapital ligaments from T2-T10 joining rib
heads usually prevent extrusion in thoracic spine
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Intervertebral Disc Disease
Survey radiographs Mineralized material in plane of intervertebral disc
space• Indicative of degeneration, not necessarily extrusion
May see mineralized material in plane of vertebral canal in case of disc extrusion• Important to use 2 views
Narrowing of intervertebral disc space• May be wedged in appearance
Narrowing of the articular facet joint space
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Intervertebral Disc Disease
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Narrow IVD space Narrow IV foramen Narrow articular facet joint
TUSCVM
Intervertebral Disc Disease
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Mineralized material in plane of vertebral canal over IVD space
TUSCVM
Intervertebral Disc Disease
Myelography 97% accurate in identifying site and lateralizing
disc hernia
CT Good for mineralized disc material; need
myleogram if disc material not mineralized
MRI Good for all types of spinal cord compression
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Intervertebral Disc Disease
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Need loss of visibility of the contrast column to say lesion is compressive
Intervertebral Disc Disease
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CT
MRI
Atlantoaxial Instability
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C1 C2
Space between the dorsal arch of C1 and the spinous process of C2
Dens (odontoid process)
Wings of C1 (atlas)
TUSCVM
Atlantoaxial Instability
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Ligaments of the A-A joint Dorsal atlanto axial ligament Alar ligaments (2) Apical ligament Transverse ligament
C1
C2
Atlantoaxial Instability
Radiographic findings Increased distance between dorsal spinous process
of C2 and dorsal arch of C1 Dorsal deviation of C2 causing step in vertebral canal Absent or small odontoid process Fractured odontoid process
Views Lateral, ventrodorsal, lateral oblique Flexed lateral must be performed after survey
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Atlantoaxial Instability
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Atlantoaxial Instability
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Agenesis of the dens
Normal
Atlantoaxial Instability
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Fracture of dens
TUSCVM
Cervical Vertebral Instability
Large breed dogs Young Great Danes (<1year) Older Dobermans (3-9 years) St. Bernards, Mastiffs, Basset Hounds…
Males affected more commonly than females
Caudal cervical spine most common (C5-7) Also C2-4 but less frequently
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Cervical Vertebral Instability
Abnormalities Congenital malformation and malarticulation of
vertebral bodies, articular facets, vertebral arches and pedicles• Dorsal vertebral tipping and subluxation• Degenerative joint disease of articular facets
Ligamentum flavum hypertrophy Hypertrophy of the dorsal annulus fibrosus and
stretching/hypertrophy of the dorsal longitudinal ligament
Intervertebral disc disease (Hansen type II)
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Cervical Vertebral Instability
Static lesion Does not change with different positions of the neck
(neutral, flexion, extension or traction)• Usually due to IVD herniation or bony abnormalities
(malformation, facets proliferation)
Dynamic lesion Changes according to the position of the neck
• Due to ligamentous hypertrophy
• Traction or flexion of the neck will the severity of the lesion; Extension will exacerbate the lesion
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Cervical Vertebral Instability
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Articular facet degenerative joint disease
TUSCVM
Cervical Vertebral Instability
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Funnel shaped appearance of cranial aspect of vertebral body with dorsal tipping of cranial aspect of vertebral body
Narrowing of vertebral canal with spinal cord compression
Courtesy L. Pack
Example of Dynamic lesion
Cervical Vertebral Instability
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Example of Dynamic and Static Lesion
Flexed view – compression of spinal cord with tipping of vertebral body and mineralized material
Traction view – the spinal cord remains compressed
TUSCVM
Lumbosacral Instability
Also known as… Cauda equina syndrome Lumbosacral stenosis…
Congenital or acquired abnormalities causing biomechanical changes Cause compression of nerve roots
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Lumbosacral Instability
Cauda equina Nerves exiting the terminal spinal cord
• Spinal cord termination- L4 in large breeds and cranial aspect ofL6 in small breeds
Clinical features Seen in cats and dogs German shepherds are predisposed
• Higher incidence seen in animals with a transitional vertebra
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Lumbosacral Instability
Etiologies Disc herniation at L6-7 or L7- S1 Spondylosis deformans and facet osteoarthrosis (DJD) Congenital lumbosacral canal stenosis
Radiographic findings Static or dynamic condition Narrow and wedged intervertebral disc space Narrow vertebral canal Ventral and lateral spondylosis deformans Articular facet osteoarthrosis
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Lumbosacral Instability
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Spondylosis
Articular facet osteoarthrosis
TUSCVM
Lumbosacral Instability
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Sclerosis and irregularity of
endplates
Wedged IVD space
TUSCVM
Lumbosacral Instability
Contrast techniques Myelography Epidurography Discography
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Vertebral Injury
Fractures Important points
• Care in handling the patient• Perform lateral view firs to rule out major fractures
before proceeding Fracture of vertebra
• Body, lamina, pedicles• Transverse or spinous processes• Endplates (young animals)
Compression fracture Subluxation/ luxation Pathologic fracture
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Vertebral Injury
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Vertebral endplate fracture with subluxation of endplate and widening of the articular facet joint. Note the vertebral canal malalignment
Vertebral Injury
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Vertebral canal malalignment due to subluxation of vertebral bodies
TUSCVM
Vertebral Injury
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Compression fracture
TUSCVM
Vertebral Injury
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Complete luxation
TUSCVM
Discospondylitis
Infection involving the intervertebral disc and adjacent endplates Mostly through hematogenous route
• Sources – bladder, heart, teeth and skin Staphylococcus spp, Escherichia coli, Brucella canis most
common Also Streptococcus spp., Pasteurella multocida, yeast-like
organisms, etc Fungal organisms also reported
Seen in young adult, male, large breed dogs
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Discospondylitis
Radiographic findings Can affect any disc space
• L7-S1, caudal cervical and mid-thoracic spine most common
Radiograph entire spine if find one lesion as there can be multiple
Can take 3-4 weeks after onset of clinical signs for radiographic changes to become visible• Similarly, resolution of radiographic changes lags behind
clinical improvement
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Discospondylitis
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Collapsed IVD spaceEndplate lysis with adjacent sclerosis
Irregularity of endplatesSpondylosis
Discospondylitis
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Discospondylitis with vertebral subluxation
Discospondylitis
Alternative imaging Myelography CT MRI Nuclear scintigraphy
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Spondylitis
Infection of a vertebral body = osteomyelitis of spine Hematogenous spread of infection from elsewhere Extension from infection of surrounding soft tissues
• Migrating grass awn Iatrogenic
• Post spinal surgery
Vertebral physitis In younger animals, adjacent to the endplate
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Spondylitis
Radiographic findings Poorly marginated osteolysis Ill-defined periosteal reaction on ventral vertebral
body• Sometimes extends to lateral aspect of vertebra
• Extends to mid vertebral body, unlike spondylosis deformans
Variable sclerosis of vertebral bodies Often multiple vertebral bodies affected
DDX – metastatic carcinoma
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Spondylitis
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Migrating grass awn – causing fuzzy, periosteal reaction
Spondylitis
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Vertebral physitis – reaction adjacent to endplate
Endplate spared PhysitisTUSCVM
Neoplasia
Benign tumors Relatively rare Osteoma Chondroma Multiple cartilaginous extostoses - MCE
(osteochondromatosis)
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MCE
Cross, J. & Tromblee, T. What is your diagnosis? J Am Vet Med Assoc (2007).
Neoplasia
Malignant tumors Primary bone tumors
• Osteosarcoma, Chondrosarcoma, Fibrosarcoma Multiple myeloma…
Metastatic neoplasia Axial skeleton (ribs, vertebra) most common site of
metastasis• Carcinomas (prostatic, bladder, mammary, perianal)
• Primary bone tumors
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Neoplasia
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Osteosarcoma – primarily osteoproductive lesion
TUSCVM
Neoplasia
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Multiple myeloma – “punched out” lesion through axial skeleton
TUSCVM
Neoplasia
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Histiocytic sarcoma – osteolytic lesion
TUSCVM
Neoplasia
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Metastatic prostatic carcinoma TUSCVM
The End
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