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NSB II > Intervertebral Disc Disease > Flashcards

Intervertebral Disc Disease Flashcards

1
Q

where can disc herniation occur?

A

any spinal cord segment!
T3-L3 most common!

but also
C1-C5
C6-T2
L4-S1
S1-S3
caudal segments

anywhere!!

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2
Q

describe the intervertebral disc

A
  1. interposed between adjacent vertebral bodies
    -not between C1-C2, not in the fused sacrum so L7-S1 is the last one we care about even though the tail does have
  2. nucleus pulposus in center: water, proteoglycans, type II collagen
    -health disc is 80% water
  3. annulus fibrosis outside: tough fibrous rings
    -thicker ventrally so often herniate dorsally up to spinal cord
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3
Q

describe the disease of IVDD

A
  1. IVD degeneration
  2. IVDD: disease
  3. IVDH: herniation!
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4
Q

describe Hansen type I IVD degeneration

A

major changes to nucleus
-loss of proteoglycans and water +/- calcification in young dogs
-annulus weakens and leas to EXTRUSION: nuclear material in vertebral canal via tear in annulus

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5
Q

describe Hansen type II IVD degeneration

A

major changes to annulus result in PROtrusion; dorsal displacement of annulus and nucleus

-more common in older larger dogs

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6
Q

describe ANNPE

A

acute non-compressive nucleus pulposus EXtrusion

contusion only

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7
Q

why do hansen type I IVDH happen?

A

genetically driven degeneration of disc!!

-young or middle aged: degen begins at 6 months in dachshunds

-certain breeds overrepresented: chondrodystophic!

-NOT because of mechanical forces of long backs an short legs; nothing can be done to prevent if it’s destined to happen

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8
Q

how long does it take for the annulus to heal/fibrose?

A

4-6 weeks! need to rest for at least that long to prevent further degeneration!!

“put them in a box”

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9
Q

describe the common signalment for IVDD type I

A

age
-90% degen by 2 years
-IVDH 2-6 years (peak 4-5)
-not puppies
-less common in older dogs

breed:
-chondrodystrophic
-possible but less common in other breeds (pit bull) but def no the young large breed!

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10
Q

describe the common history of type I IVDH

A
  1. acute: hours to days; sudden tear in annulus causes extrusion of nucleus and compression of spinal cord
  2. typically progressive: continued damage to cord and possibility for continued extrusion
  3. typically painful due to compression of meninges/nerve
  4. can be ANY neuroanatomic localization
    -T3-L3 85% of cases
    -T10-L2 most common of those: no intercapital ligaments, high motion, stable to unstable junction
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11
Q

describe exam findings of type I IVDH

A
  1. T10-L2 most common so typically have T3-L3 findings
    -hind limb weakness or paralysis with normal to increased reflexes
  2. can use cut trunci cut off and pain to further localize
    -pain is NOT a localization
  3. signs will range in severity depending on severity of compression
    -proprioceptive ataxia first
    -voluntary motor control goes next
    -then loss of sensation/nociception last
    -based on fiber size! regain in inverse order
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12
Q

what is nociception?

A
  1. conscious perception of noxious stimulus
  2. a BILATERAL MULTISYNAPTIC pathway!!
    loss requires functional transection of spinal cord!!!
  3. MUST look for patient response NOT JUST withdrawal of limb
  4. NEVER need to check for sensation in a patient with voluntary motor!! nociception lost after lose motor so should be inact, no need to pinch the puppy
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13
Q

describe radiographs to test for IVDH

A
  1. only provide EVIDENCE of disc disease
  2. supports a presumptive diagnosis, but not definitive
  3. narrow IVD space
  4. narrow IV foramen
  5. narrow articular facet joint
  6. if you’re lucky: see mineralized IVD or mineralized material in plane of vertebral canal over IVD space
  7. finding any of these does not mean that those are the reason why the dog can’t walk! just support a diagnosis

not wrong to take in any dog with myelopathy or painful neck or back!

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14
Q

describe MRI to make a definitive diagnosis of IVDH

A
  1. dehydrated dark grey discs or even black if mineralized; just means disc degeneration, not spinal cord compression though
  2. herniated disc! black spot in spinal cord
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15
Q

describe CT to diagnose IVDH

A
  1. only for mineralized disc
  2. does not work for all cases
  3. cannot visualize spinal cord
    -rarely used
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16
Q

describe myelogram to diagnose IVDH

A
  1. rarely used anymore/outdated
  2. inject contrast into subarachnoid space to see where lose = compression
  3. cannot visualize spinal cord
17
Q

when is type I disc herniation a good presumptive diagnsosis?

A

signalment: young to middle aged chondrodysplastic dog

history: acute onset, progressive

exam findings: any localization and any severity!
-T3-L3 most common
-pain on exam common

diagnostic findings: evidence of disc disease on rads; if not see, don’t take off list, might not always see!

(MRI would be definitive)

18
Q

when is type I IVDH NOT a good presumptive diagnosis?

A

signalment: 6mo dachshund (too young), 1 year old great dane (wrong breed)

history: 3 month progressive history; possible in the correct breed but unlikely

exam findings: cranial thoracic cutaneous trunci cutoff

19
Q

what are the 2 categories of treatment of type I IVDH

A
  1. conservative:
    -exercise restriction
    -medication
  2. surgical: hemilaminectomy to removed compressive disc
20
Q

define a successful outcome post IVDH treatment

A
  1. able to walk: should see improvement every two weeks in reverse order of how they lost it
  2. pain free on no pain meds
  3. urinary and fecal continence
21
Q

what is the biggest factor in choosing treatment for type I IVDH?

A

severity and prognosis!

  1. pain only: 95% success of both pain management and surgery; choose meds is okay
  2. ambulatory paraparesis and GP ataxia: same as pain free
  3. non-ambulatory paraparesis:
    -80% success with medical (not bad, but 2/10 won’t walk again so)
    -95% success with surgery- choose surgery if you can
  4. paraplegia (loss of all voluntary motor):
    -60% success with med mgmt- not great
    -90% success with surgery- choose surgery if you can
  5. paraplegia absent sensation
    -<5% success with med mgmt
    -50% success with surgery
    -time matters!! but a mystery in real life of when lost sensation
    <24 hrs: surgery is 50% successful
    24-48 hrs: unsure
    >48 hrs: <10% success with surgery

as soon as you can’t walk you are now a surgical candidate! but if money is an issue you don’t have to jump straight to euth, always at least try medical management!!

22
Q

describe time to recovery with medical or surgical management

A
  1. medical: 6 weeks
  2. surgical: less than 2 weeks and a more complete recovery
23
Q

describe recurrence of IVDH type I for both types of treatment?

A

conservative: 50%
-25% fail medical management and progress to where they need surgery
surgical: 10%

24
Q

when to refer with type I IVDH? (4)

A

cannot refer too early but can refer to late!!

when to refer:
1. acute and severe (even if still ambulatory)
-progressing fast
2. non-ambulatory!!!
3. french bulldog!!
4. not responding to medical management

25
Q

describe exercise restriction

A
  1. STRICT cage rest for 4-6 weeks to allow fibrosis of torn annulus and prevent herniation of more disc material
    -most owners “over it” by 4 weeks
  2. followed by gradual return to exercise
26
Q

describe anti-inflammatory medical managment

A

corticosteroids versus NSAIDs
-no consensus, contact a specialist, just DONT USE TOGETHER

  1. prednisone 0.5 mg/kg/day
  2. dexamethasone 0.05-0.1 mg/kg/day: not recommended due to severe GI side effects (injectable)
27
Q

describe pain medication management

A
  1. gabapentin (neurontin) 10 mg/kg BID-TID

+/- amandatine 2-5 mg/kg once daily

28
Q

describe follow-up from conservative treatment

A

when recheck?
-critical time points: it takes 2 weeks to see improvement; good if dog is walking
-tell them you need to see them ASAP if dog stops walking!!
-if rapid progression to plegic: recheck in 1-2 days to see if come up with money once lose sensation

seek emergency care: when stops walking!

on recheck: looking for orderly return to function

29
Q

describe spinal shock phenomenon
(6)
(another presentation of disc disease)

A
  1. peracute/acute onset
  2. severe T3-L3 lesion: paraplegia/almost paraplegia; is an asymmetrical disease even though commonly affects both pelvic limbs! the worst side is thew one with shock
  3. immediately LMN caudal to the lesion
    -no anal tone/perineal reflex
    -decreased muscle tone
    -no patellar reflex
    -no withdrawal reflex
  4. spontaneously resolves
    -perineal normal within minutes
    -patellar normal within hours
    -muscle tone and withdrawal can take days to weeks to normalize
  5. look for other signs of T3-L3:
    -cutaneous trunci cut off
    -pain
    (to convince yourself is T3-L3)
    can’t be paraplegic due to L6-S1 bc femoral nerve still flexes hips
  6. localization: T3-L3 with spinal shock
    -T3-L3 pain and/or cutaneous trunci cut off
    -normal patellar reflexes
    -decreased muscle tone pelvic limbs
    -decreased withdrawal pelvic limbs
30
Q

describe nerve root signature (4)
(another presentation of disc dog)

A
  1. in thoracic (more common) or pelvic limbs
  2. lameness (very lame) without orthopedic cause
  3. may be non weight bearing
  4. typically can decide based on exam without imaging
    -can’t find any reason on ortho exam for why so lame
31
Q

describe ascending descending myelomalacia/myelomalacia (6)

A
  1. hemorrhagic necrosis and liquefaction of spinal cord
    -unknown inciting cause/pathophysiology
  2. occurs secondary to type I IVDH (rare report after trauma)
  3. ONLY in dogs with absent sensation/nociception (warn owners to look for signs if doing no sx)
    -33% french bulldogs
    -10% all other breeds
  4. clinical signs: (ascending and descending usually both happen but might be at different rates)
    -ascending:
  5. cutaneous trunci ascends and eventually becomes absent
  6. loss of abdominal muscle tone
  7. thoracic limbs become weak (seen as lay them on side and too weak to right themselves as first sign)
  8. hypoventilation (abdominal breathing not diaphragmatic)

-descending:
1. pelvic limbs become LMN
2. loss of anal tone and perineal reflex
3. loss of tail tone

  1. +/- fever and painful (may not really see clinically, literature just says)
  2. irreversible!! euthanasia is necessary!!!
32
Q

describe schiff-sherrington phenomenon (another presentation of disc disease) - FYI Barber said she won’t ask a test question on it

A
  1. severe T3-L3 lesions (paraplegia) to border cells (lumbar spinal cord) that normally provide inhibition to thoracic limb extensor tone; resulting in rigid extension of thoracic limbs
  2. could be from pain
  3. does not change prognosis (just a fun gee whiz)
33
Q

describe CERVICAL type I disc herniation signalment

A
  1. 15% of disc herniation cases
  2. chondrodysplastic most common
    -dachshunds!! french bulldogs, toy poodle, cocker spaniel, beagles mostly
  3. large breeds also: labs, rotties, dobies, dalmations
  4. occurs most common between 4-8 years old
34
Q

describe CERVICAL type I disc herniation exam findings

A
  1. pain ONLY is the most common presentation!
    -nerve root signature is also more common
  2. only 1/3 will be non-ambulatory (more room up there so can compress for pain without taking away walking ability)
  3. often asymmetrical thanks to the dorsal longitudinal ligament
35
Q

describe CERVICAL type I disc herniation diagnostics

A
  1. rads: may be normal, but still a good idea with severe pain and large breed to rule out neoplasia
  2. MRI!!!!
36
Q

describe CERVICAL type I disc herniation treatment and prognosis

A

treatment:
1. conservative management is same as for TL type I IVDH
-less likely to respond; very hard to manage pain!!
-50-85% recovery
-33% recurrence

  1. ventral slot: >95% recovery

prognosis:
1. pain, mild paresis:
-medical mgmt: 50-85%
-sx: >85%

  1. non-ambulatory paresis
    -medical: unknown
    -sx: >95%
  2. recurrence
    -medical: 33%
    -sx: 10-33%
37
Q

describe Hansen type II IVDH (will come up as a test question as a differential) (5)

A
  1. non-chondrodystrophic large breeds
  2. older (>6-8 years)
  3. chronically progressive (several month history)
  4. +/- painful
  5. prognosis is not as good as with type I
    -71% treated with sx have clinical improvement for >12 months but could actually make worse with sx (might be adhered to spinal cord, might be hard as a rock)- really just do sx to keep dog from getting worse
    -29% medically (steroids and rest) treated have sustained clinical improvement
38
Q

describe acute non-compressive nucleus pulposus extrusion (ANNPE) (6)

A
  1. trauma ot vigorous exercise causes hydrated nucleus to herniate through tear in annulus and dissipate

2 clinical signs from contusion of spinal cord

  1. any age (young more common)
  2. any breed
  3. acute (or peracute) onset
    -differential diagnosis with FCEM (see Kent lecture)
  4. > 80% improve with time
39
Q

describe IVDD in cats (5)

A
  1. disc extrusion uncommon!
  2. mean age is 9.8 years
  3. reported prognosis with surgery 80%
  4. ANNPE more common in cats
  5. prognosis 90% for good recovery

NSB II (50 decks)

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