Small Animal Vertebral Column

sihirlifil's version from 2017-11-01 21:25

Normal Anatomy

Question Answer
Modality of choice when assessing spinal fractures?CT
More sensitive to detecting fractures of individual parts of vertebrae, including dorsal lamina; allows for complete imaging of vertebral column without having to change patient's position; multiplanar reconstruction available in most units
Normal dog/cat spine vertebral formulaC7, T13, L7, 3S, Cd15-20
How are C1 and C2 anatomically different?Have multiple centers of ossification
Hemal arches = Small bony hoops on the ventral aspect of coccygeal vertebral bodies up to about Cd6
Anticlinal vertebra = T11
The IVD space between T10-11 is ___ compared to adjacentNarrowed
Landmark of C6?Large ventral laminae
Rib heads are Cr or Cd to corresponding vertebrae?Cranial
L3/L4 ventral outline is ill-defined why?Origin of diaphragmatic crura
How are the dorsal spinous processes of C1 and C2?Dors spinous processes of C2 should overlap with arch of C1
Normally how should IVD look?Adjacent IVD spaces & IV foramina similar width & size
Normally how should vertebrae look?Adjacent should be similar size (except C7 & L7 may be shorter), shape, & radiopacity
Should be continuously aligned (no steps)

Anomaly, Alignment, Degenerative

Question Answer
Indications for spinal radiographyNeuro deficits
Abnormal posture (suspicion of anomaly)
Abnormal swellings/masses
Variable # of vert: types?Aplasia (missing) or supernumerary (too many)
Clinically insignificant, may just be confusing when trying to localize a lesion
Abnormal shape: hemivertebra = Wedge-shaped, with short aspect either dorsally, ventrally, or laterally
Kyphosis = Dorsal deviation
Lordosis = Ventral deviation
Scoliosis = Lateral deviation
Lateral hemivertebra
Top: Dorsal hemivertebra
Bottom: Ventral hemivertebra
Butterfly vertebra = Bow-tie shaped on VD
Vertebral shape anomalies occur mainly in which breeds?Screw-tail like bulldogs, pugs, Boston terriers (kinked tail often caused by coccygeal hemivertebrae)
How do shortened vertebrae affect the rest of the spine?Crowding of ribs & dorsal spinous processes
What are the red arrows indicating? Yellow?
Dorsal & ventral lengths of the vertebral bodies are dissimilar (normal in bulldogs, pugs, Boston terriers)
Yellow = Bony proliferation ventral to the vertebral bodies (spondylosis)
Block vertebra = Fusion
Can be congenital, traumatic, sequel to discospondylitis
C5 & C6 fused (dog)
No IVD space & foramen
Only 6 cervical segments counted
Transitional vertebrae = Features of 2 adjacent regions of the vertebral column
Examples of transitional vertebraeLumbar vertebrae with ribs
Lumbar vertebrae partially fused with sacrum/ilium
Sacral segments not fused (should be by 1 year)
Lumbosacral transitional vertebra in a dog
Right side: L7 transverse process articulates with the iliac wing
Left side: normal
Lumbosacral transitional vertebra in a cat: Lumbarisation of S1
Normally no visible IVD space between sacral segments!
Whats going on in A? B?
A: Left transverse process of L7 articulates with ilium, appears continuous with L wing of sacrum
B: Right L7 transverse process articulates with ilium, while L sacroiliac joint almost normal
Both are transitional lumbosacral segment
Lumbosacral transitional segments may be associated with?Degen LS formaminal stenosis (cauda equina syndrome)
Osteoarthritis of coxofemoral joints
+/- inherited in GSD
Spinal dysraphism = Congenital abnormal closure of neural tube
Spina bifida = Failure of dorsal aspect of vertebra to form properly --> dorsal midline cleavage of vertebral arch & dorsal spinous processes
Spina bifida occurs mostly in?Brachycephalics
Spina bifida
Arrows = double dorsal spinous processes
How does spina bifida look on lateral projection?MAY NOT BE VISIBLE!
Dens hypoplasia leads to?Atlantoaxial subluxation
Dorsocranial subluxation of C2
Hypoplasia of dens axis
Arrow = missing odontoid peg
Rostrocaudal open mouth projection of dens of axis is NOT RECOMMENDED in patients with suspected atlantoaxial instability
Abnormal vertebral size happens when?Dwarfism
Primordial dwarfism = Proportionate decreased size of skull, axial, & appendicular skeleton
Chondrodystrophoid dwarfism = Disproportionately decreased size of limbs, cranial base, & vertebrae
Causes of malalignmentCongenital, caused by vertebral anomalies leading to malformed vertebrae
Postural, caused by pain
Types of malalignmentFracture, luxation, subluxation; can be combination
How does craniodorsal subluxation of C2 happen?Dens anomaly/trauma
Rupture/absence of ligaments between C1 & C2
(Craniodorsal subluxation of C2: breeds)(Small/toy: Yorkshire terrier, mini poodle, pekingese, pomeranian, Shi Tzu, Dachshund, chihuahua, Maltese; <1 year)
Cervical vertebral malformation aka?Canine 'wobbler syndrome'
Caudal cervical spondylopathy
Chronic cervical myelopathy
Cervical vertebral malformation: what's going on?Absolute or relative stenosis of the vertebral canal, causing spinal cord compression
Fracture of L6
Cervical vertebral malformation: big breed predisp?Doberman
How does cervical vertebral malformation look?Plough/cone-shaped vertebral body
Flaring of caudal endplate
Wedge-shaped disc spaces, narrow vertebral canal, prominent craniodorsal aspect of vertebral body (appear dorsally deviated)
Cervical vertebral malformation: dx?Compressive lesions need myelography or MRI/Myelo CT
Cervical vertebral malformation: how is the vertebral column?Instability, often dynamic, exacerbated under hyperflexion/extension
C6-C7 malalignment, marked dorsal deviation of cranial endplate of C7, causing step formation & narrowing of vertebral canal
What's going on with these 2 x-rays?
Lateral myelograms of the same dog, bottom is in hyperextention (which exacerbates condition of cervical vertebral malformation, comes up more dorsally)
Cervical vertebral malformation: CS?Neurological signs from compression of spinal cord
Lumbosacral fracture-luxation
Fractured caudoventral aspect of L7 & lumbosacral subluxation
(Other causes of vertebral canal stenosis)(Hyperplasia of interarcuate ligament, joint capsule, dorsal longitudinal ligament,, dorsal annulus fibrosis of IVD; may hypertrophy attempting to stabilize unstable caudal cervical vertebrae)
Spondylosis deformans =New bone formation at level of attachment of outermost annular fibers of annulus fibrosis
Not clinically significant, older large-breed dogs >2y
Spondylosis deformans
Small bony spurs / bridging of IV disc space of adjacent vertebrae
Well-defined new bone, homogenous opacity, smooth contours
Degenerative canine lumbosacral stenosis: what is it?Acquired lesion to nerve roots associated with cauda equina syndrome
Narrowing of IV foramina & impingement on nerve roots cause CS 2ry to compression of nerve roots
Degenerative canine lumbosacral stenosis: caused by?Stenotic lumbar/sacral vertebral, OCD-like lesion at craniodorsal aspect of 1st sacral vertebra
Lumbosacral malalignment/instability/disc herniation
Fibrous tissue in ventral aspect of vertebral canal at LS junction
Spondylosis/osteophytes of diarthodial (facet) joints
Degenerative canine lumbosacral stenosis: associated with?Static or dynamic malalignment
Best demonstrated on flexed lateral projections (sacrum subluxates ventral to L7)
Higher incidence of transitional vertebrae (causative factor)
Degenerative canine lumbosacral stenosis: common in who?Older, large-breed dogs
Degenerative canine lumbosacral stenosis
What condition is this? Stars = ?
Osteophyte formation & remodelling of synovial joints
LS spondylosis: associated with?Dynamic malalignment
T/F Spondylosis & LS instability are both indicative of cauda equina syndromFalse! Neither are indicative of degen LS stenosis either
Diffuse idiopathic skeletal hyperostosis (DISH) = Extracortical new bone formation leading to osseus bridging between the vertebral bodies & dorsal spinous processes
More than 3 segments fuse
DISH: breed?Boxer!
DISH: associated with?Spondylarthrosis
IVD disease
Spinal dural ossification aka?Ossifying pachymeningitis
Spinal dural ossification: CS?Not clinically significant but may help localize extradural lesions
Spinal dural ossification: what's going on?Dura mater ossifies; mineral +/- linear opacity in vertebral canal
Spinal dural ossification: happens in who?Older large-breed gods
Spinal dural ossification
List of degenerative abnormalitiesDegenerative canine LS stenosis
Spondylarthrosis: DJD of diarthodial (synovial) joints of vertebral column (+/- synovial cysts, =extension of synovial cavity)
DISH (bony proliferation between dorsal spinous processes & at lvl of interarcuate foramina)
Spinal dural ossification
Synovial cysts best dx byMRI

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