Lecture 10

Question 1

What is block vertebra?

Answer 1

-partial or complete fusion of two adjacent vertebral bodies
-typically an incidental finding

Question 2

What are the characteristics of hemivertebra?

Answer 2

-failure of vertebral body to form completely
-can be incidental in minor cases
-can cause compression of spinal cord in severe cases
-bred for in breeds with screw tails
-causes paraparesis and incontinence at young age
-diagnosed with radiographs and advanced imaging

Question 3

What is shown in this image?

Answer 3

hemivertebra

Question 4

What is spina bifida?

Answer 4

failure of the neural tube to close or formation of cleft

Question 5

How does a meningocele differ from a myelomeningocele?

Answer 5

-meningocele is an outpouching of meninges and CSF following spina bifida
-myelomeningocele is an outpouching of spinal cord, meninges, and CSF following spina bifida

Question 6

What are the clinical signs of spina bifida?

Answer 6

-young age at onset/presentation
-commonly english bulldogs and manx cats
-variable neuro. deficits; often paresis or ataxia

Question 7

What are the characteristics of sacrocaudal dysgenesis with spina bifida?

Answer 7

-agenesis of caudal/sacral vertebrae
-autosomal dominant trait in manx cats
-usually not treatable

Question 8

What are the neurologic deficits seen in sacrocaudal dysgenesis with spina bifida?

Answer 8

-paraparesis or paraplegia
-urinary and/or fecal incontinence
-loss of tone, reflexes, and nociception in anal and perineal area (megacolon, atonic bladder)

Question 9

How is spina bifida diagnosed and treated?

Answer 9

-diagnosed via imaging
-treated surgically

Question 10

What are the characteristics of myelodysplasia of weimaraners?

Answer 10

-aka spinal dysraphism
-spinal cord does not form correctly
-inherited, co-dominant lethal gene
-NKX2-8 gene on chromosome 8

Question 11

What are the clinical signs of myelodysplasia of weimaraners?

Answer 11

-4 to 6 weeks old at onset
-non-progressive paraparesis
-non-painful
-no spinal hyperesthesia
-“bunny hopping”

Question 12

What is the prognosis for myelodysplasia of weimaraners?

Answer 12

no treatment; recommend aggressive physical therapy or euthanasia

Question 13

What are the characteristics of atlantoaxial subluxation?

Answer 13

-dorsal displacement of cranial aspect of body of axis into vertebral canal due to lack of dens
-thought to be related to degeneration of dens or aplasia/hypoplasia of dens
-ligaments that typically stabilize the joint attach to the dens

Question 14

Which ligaments are involved in stabilizing the AA joint?

Answer 14

-nuchal ligament
-atlanto-axial ligament
-alar and apical ligaments
-transverse ligament

Question 15

What is the signalment and history for AA subluxation?

Answer 15

-young animals; typically 6 to 19 months
-toy or miniature breeds
-acute or chronic presentation

Question 16

What are the clinical signs of AA subluxation?

Answer 16

-cervical hyperesthesia
-mild tetraparesis with ataxia up to tetraplegia
-normal to exaggerated spinal reflexes
-respiratory paresis

Question 17

Why is it important to AVOID ventroflexion in patients with a suspected AA subluxation?

Answer 17

ventroflexion can worsen the subluxation and potentially lead to death

Question 18

What is shown in this image?

Answer 18

AA joint with normal space between C1 and C2

Question 19

What is shown in this image?

Answer 19

AA subluxation and increased space between C1 and C2

Question 20

What are the medical treatment steps for AA subluxation?

Answer 20

-cage rest for 6 to 8 weeks
-external coaptation (bandaging or brace) with good nursing care

Question 21

What is the surgical approach for AA subluxation?

Answer 21

ventral fixation with screws and bone cement

Question 22

What are the characteristics of multiple cartilaginous exostoses?

Answer 22

-various species possible; dogs more common
-benign proliferation of bone at metaphyseal region in young animals
-enlarge during growth; stop at skeletal maturity
-no breed or sex predilection
-clinical patients treated with surgical excision

Question 23

What is shown in this image?

Answer 23

multiple cartilaginous exostoses

Question 24

What is shown in these images?

Answer 24

multiple cartilaginous exostoses with a nodule pushing down onto the spinal cord

Question 25

What are the characteristics of caudal occipital malformation syndrome (COMS)?

Answer 25

-aka chiari-like malformation -skull shape is too small to fit all of the brain matter

Question 26

What is syringomelia?

Answer 26

fluid cavity within spinal cord parenchyma

Question 27

What are the components of COMS?

Answer 27

-hypoplasia/dysplasia of occipital bone results in crowding of caudal fossa -compression of cerebellum +/- herniation via foramen magnum -syringomyelia formation due to pressure build up and fluid accumulation -medullary kinking/elevation of medulla from ventral surface of skull at cervicomedullary junction -ventriculomegaly from pressure build up

Question 28

Which breed most commonly presents with COMS?

Answer 28

cavalier king charles spaniels; nearly all individuals have some degree of COMS

Question 29

What are the clinical signs of COMS?

Answer 29

*variable age at onset; typically by 4 years *neuropathic pain -vocalization -spinal hyperesthesia -phantom scratching -sleep disturbances *cervical myelopathy -proprioceptive deficits -LMN deficits to thoracic limbs -paresis and/or ataxia *cerebellovestibular and/or brainstem dysfunction *scoliosis/cervical torticollis

Question 30

What is shown in these images?

Answer 30

A and B: normal MRI C: cerebellar herniation, smaller occiput, kinking of medulla (COMS) D: severe case of COMS

Question 31

What are the three categories of medications used in medical management of COMS?

Answer 31

-analgesics -medications that reduce CSF production -corticosteroids

Question 32

When should surgery be considered in COMS patients?

Answer 32

-patients that suffer from adverse drug effects -patients with neurologic signs that progress despite medical management -syringomyelia greater than 3 mm in diameter

Question 33

What is the surgical procedure done to treat COMS?

Answer 33

-foramen magnum decompression; removal of portion of back of skull and portion of C1 -possible cranioplasty to protect now-exposed tissues

Question 34

What is the prognosis for COMS with medical management?

Answer 34

-temporary improvement in many cases short-term -lack of information on long-term prognosis

Question 35

What is the prognosis for COMS with surgical management?

Answer 35

-80-94% improvement in clinical signs/pain in the short-term -25-47% relapse rate in the long-term when decompression alone is performed