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 VCA 341 – The Spine Matthews

Spondylosis Deformans Courtesy Dr. L. Pack VCA 341 – The Spine Matthews

Intervertebral Disc Disease Anatomy Thrall Veterinary Diagnostic Radiology 5th Ed Insert picture VCA 341 – The Spine Matthews

Intervertebral Disc Disease Protrusion Herniation Extrusion Insert picture http://www.backandneckpain.ca/understanding-your-spine/499-2/ VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

Intervertebral Disc Disease Narrow IVD space Narrow IV foramen Narrow articular facet joint TUSCVM VCA 341 – The Spine Matthews

Intervertebral Disc Disease Mineralized material in plane of vertebral canal over IVD space TUSCVM VCA 341 – The Spine Matthews

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 (Kirberger, Vet Rad) VCA 341 – The Spine Matthews

Intervertebral Disc Disease Need loss of visibility of the contrast column to say lesion is compressive VCA 341 – The Spine Matthews

Intervertebral Disc Disease CT MRI VCA 341 – The Spine Matthews

Atlantoaxial Instability Space between the dorsal arch of C1 and the spinous process of C2 C1 C2 Dens (odontoid process) Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord Wings of C1 (atlas) TUSCVM VCA 341 – The Spine Matthews

Atlantoaxial Instability Ligaments of the A-A joint Dorsal atlanto axial ligament Alar ligaments (2) Apical ligament Transverse ligament C2 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord C1 VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

Atlantoaxial Instability Groves187683 VCA 341 – The Spine Matthews

Atlantoaxial Instability Normal Groves187683 Agenesis of the dens VCA 341 – The Spine Matthews

Atlantoaxial Instability Fracture of dens Petty 221642 TUSCVM VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

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) Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

Cervical Vertebral Instability Articular facet degenerative joint disease Flint 203697 TUSCVM VCA 341 – The Spine Matthews

Cervical Vertebral Instability Example of Dynamic lesion Funnel shaped appearance of cranial aspect of vertebral body with dorsal tipping of cranial aspect of vertebral body Flint 203697 Narrowing of vertebral canal with spinal cord compression VCA 341 – The Spine Matthews Courtesy L. Pack

Cervical Vertebral Instability Example of Dynamic and Static Lesion Flexed view – compression of spinal cord with tipping of vertebral body and mineralized material TUSCVM Traction view – the spinal cord remains compressed VCA 341 – The Spine Matthews

Lumbosacral Instability Also known as… Cauda equina syndrome Lumbosacral stenosis… Congenital or acquired abnormalities causing biomechanical changes Cause compression of nerve roots Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

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 Annulus may stretch, partially rupture or hypertrophy and bulge into the vertebral canal, compressing the cord VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

Lumbosacral Instability Articular facet osteoarthrosis Spondylosis TUSCVM VCA 341 – The Spine Matthews

Lumbosacral Instability Subluxation of sacrum Wedged IVD space Sclerosis and irregularity of endplates TUSCVM VCA 341 – The Spine Matthews

Lumbosacral Instability Contrast techniques Myelography Epidurography Discography VCA 341 – The Spine Matthews

Vertebral Injury Fractures Important points Fracture of vertebra 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 VCA 341 – The Spine Matthews

Vertebral Injury Vertebral endplate fracture with subluxation of endplate and widening of the articular facet joint. Note the vertebral canal malalignment VCA 341 – The Spine Matthews

Vertebral Injury Vertebral canal malalignment due to subluxation of vertebral bodies TUSCVM VCA 341 – The Spine Matthews

Vertebral Injury Compression fracture VCA 341 – The Spine Matthews TUSCVM VCA 341 – The Spine Matthews

Vertebral Injury Complete luxation TUSCVM VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

Discospondylitis Collapsed IVD space Endplate lysis with adjacent sclerosis Irregularity of endplates Spondylosis VCA 341 – The Spine Matthews

Discospondylitis with vertebral subluxation VCA 341 – The Spine Matthews

Discospondylitis Alternative imaging Myelography CT MRI Nuclear scintigraphy VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

Spondylitis Radiographic findings DDX – metastatic carcinoma 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 VCA 341 – The Spine Matthews

Spondylitis Migrating grass awn – causing fuzzy, periosteal reaction Ledford VCA 341 – The Spine Matthews

Spondylitis Vertebral physitis – reaction adjacent to endplate Endplate spared Physitis TUSCVM VCA 341 – The Spine Matthews

Neoplasia Benign tumors Relatively rare Osteoma Chondroma Multiple cartilaginous extostoses - MCE (osteochondromatosis) MCE Cross, J. & Tromblee, T. What is your diagnosis? J Am Vet Med Assoc (2007). VCA 341 – The Spine Matthews

Neoplasia Malignant tumors Metastatic neoplasia Primary bone tumors Osteosarcoma, Chondrosarcoma, Fibrosarcoma Multiple myeloma… Metastatic neoplasia Axial skeleton (ribs, vertebra) most common site of metastasis Carcinomas (prostatic, bladder, mammary, perianal) VCA 341 – The Spine Matthews

Neoplasia Osteosarcoma – primarily osteoproductive lesion TUSCVM VCA 341 – The Spine Matthews

Neoplasia Multiple myeloma – “punched out” lesion through axial skeleton TUSCVM VCA 341 – The Spine Matthews

Neoplasia Histiocytic sarcoma – osteolytic lesion VCA 341 – The Spine TUSCVM VCA 341 – The Spine Matthews

Neoplasia Metastatic prostatic carcinoma VCA 341 – The Spine Matthews TUSCVM VCA 341 – The Spine Matthews

The End VCA 341 – The Spine Matthews