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 Sacral 3 (fused) Caudal Variable VCA 341 – The Spine Matthews

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 The spinous processes become more prominent from C4 caudally, with the spinous process of C7 being the largest. The disc space at C2-3 appears narrow compared to C3-4. On a lateral radiograph, the articular processes are positioned obliquely and superimposed over the intervertebral foramina and vertebral canal. VCA 341 – The Spine Matthews

Cervical Spine C1 C2 C3 C5 VCA 341 – The Spine Matthews

Cervical Spine atlas C1 axis C2 C3 C5 VCA 341 – The Spine Matthews 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 VCA 341 – The Spine Matthews

Thoracic Spine T11 T10 Anticlinal vertebra Anticlinal disc space is narrow normally T11 Proximal ribs T10 TUSCVM VCA 341 – The Spine Matthews

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). } Do not mistake for mineralized intervertebral disc material! VCA 341 – The Spine Matthews

Lumbar Spine TUSCVM VCA 341 – The Spine Matthews

Thoracic Spine Accessory process TUSCVM VCA 341 – The Spine Matthews

Lumbar Spine L3 L4 Attachment for diaphragmatic crus TUSCVM VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

Sacral / Caudal Vertebra VCA 341 – The Spine Matthews

Lumbosacral Junction Ilial wings Articular facet joint TUSCVM VCA 341 – The Spine Matthews

Lumbosacral Junction Margins of the sacrum VCA 341 – The Spine Matthews TUCSVM

Typical Vertebra Right and left pedicles form walls, body forms floor and lamina forms roof of vertebral canal VCA 341 – The Spine Matthews

Ligamentous Structures From Veterinary Anatomy of Domestic Animals, 3rd Ed, Konig and Liebich Konig and Liebich, Veterinary Anatomy of Domestic Animals, 3rd Ed VCA 341 – The Spine Matthews

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 Collimate, pseudonarrowing VCA 341 – The Spine Matthews

Survey Radiography Lateral cervical radiograph Ventrodorsal cervical VCA 341 – The Spine Matthews

Survey Radiography Lateral thoracic radiograph VCA 341 – The Spine Matthews

Survey Radiography Beware of “pseudonarrowing” of disc spaces Artifactual narrowing due to divergence of x-rays Collimate, pseudonarrowing Kishigami, Y.et al. Vet Radiol Ultrasound 41, 9–18 (2000). VCA 341 – The Spine Matthews

Pseudonarrowing VCA 341 – The Spine Matthews

Radiography and Contrast Techniques VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

Myelography Site for cervical injection Site for lumbar injection Diaz, F. In Practice 27, 502-510 (2005). VCA 341 – The Spine Matthews

Myelography Indications Contraindications 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 Contraindications Inflammatory disease (meningitis) Bleeding diatheses Evidence of vertebral instability (could increase spinal cord damage) VCA 341 – The Spine Matthews

Normal Myelogram Courtesy Dr. L. Pack VCA 341 – The Spine Matthews

Extradural Lesion Extruded intervertebral disc material L3 L3 L4 VCA 341 – The Spine Matthews

Intradural/Extramedullary Lesion Golf tee sign VCA 341 – The Spine Matthews

Intramedullary Lesion Widening of spinal cord due to spinal cord tumor (glioma) Courtesy Dr. L. Pack VCA 341 – The Spine Matthews

Anomalous Diseases VCA 341 – The Spine Matthews

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) VCA 341 – The Spine Matthews

Hemivertebra Butterfly vertebra VCA 341 – The Spine Matthews 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 VCA 341 – The Spine Matthews

Block Vertebra TUCSVM VCA 341 – The Spine Matthews

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 VCA 341 – The Spine Matthews

Transitional Vertebra Sacralization of L7 VCA 341 – The Spine Matthews

Spina Bifida Part of general defect called Spinal Dysraphism Two types Failure of neural arch to close during embryogenesis Two types Spina bifida occulta No spinal cord or meningeal involvement No clinical signs typically Spina bifida manifesta Protrusion of the meninges (meningocele) or meninges and spinal cord (meningomyelocele) Associated clinical signs VCA 341 – The Spine Matthews

Anomalous Diseases Common in screw-tailed breeds Bulldogs, Boston Terriers, Pugs, Manx cats Failure of fusion of spinous processes VCA 341 – The Spine Matthews

Other Anomalies Scoliosis Lordosis Kyphosis 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) VCA 341 – The Spine Matthews

The End VCA 341 – The Spine Matthews