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3. Cat & Dog 3 > Myelopathies > Flashcards

Myelopathies Flashcards

1
Q

grey matter is made of what? where in the CNS do we find it? what are the types of neurons?

A

neuronal cell bodies
<><><><>
* Sensory neurons
> Dorsal root ganglion / dorsal horn
* Interneurons
* LMNs
> Ventral horn
> To muscles

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2
Q

Spinal cord: Anatomy
- at what vertebra does it terminate in large vs small dogs? cats?

A

◦ Large-breed dogs > L6 vertebra
◦ Small-breed dogs > L7 vertebra
◦ Cats > L7-S1vertebrae

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3
Q
  • Spinal cord divided in segments:
    (dog numbers)
  • how do spinal cord segments line up with vertebra
A

◦ 8 cervical
◦ 13 thoracic
◦ 7 lumbar
◦ 3 sacral
◦ ≥ 2 caudal
<><><><>
note spinal segment numbers switch from exiting cranial to vertebral body to caudal at C8
<><><><>
— Segments NOT always lie in the same number vertebra
— Most segments are cranial to vertebra — Lesion localization: SEGMENTS

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4
Q

issues that affect gait (and posture)

A
  1. Ataxia
    - Proprioceptive (spinal)
    - Vestibular
    - Cerebellar
  2. Paresis (weakness)
    - motor function
  3. Lameness
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5
Q

Proprioceptive ataxia - what structures might we have issues with?

A

Sensory function:
1. Receptors (proprioceptors): Joints, tendons, muscles
2. Ascending proprioceptive tracts
3. To cerebral cortex (conscious perception)

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6
Q

Motor function
- what neurons are involved?
- deficits?

A

◦ Control activity muscles (brain to muscles)
◦ Required to move limbs (muscle contraction)
<><>
Requires 2 neurons:
– UMN
– LMN
<><>
◦ Deficit: PARESIS (weakness)

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7
Q

UMN and LMN - where are the cell bodies and axons? what do they do?

A

UMN
◦ Cell body: Brain
◦ Axons: descending WM
◦ “UMN tells LMNs what to do” (descending inhibition)
<><><><>
LMN
◦ Cell body: ventral horn GM, brainstem nuclei
◦ Axon: PNS to muscle
◦ Responsible for the reflex motor activity (patellar reflex)

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8
Q

Paresis/paralysis - what is this? where might lesions be?

A
  • Lost of voluntary motor function (weakness)
    > Lesion affecting UMN or LMN
  • PARESIS: Partial loss
  • PARALYSIS (-plegia): Complete absence
    – Monoparesis / Monoplegia
    – Paraparesis / Paraplegia > back limbs
    – Tetraparesis /Tetraplegia
    – Hemiparesis / Hemiplegia > both limbs on same side
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9
Q

UMN lesion clinical signs

A

— Paresis (weakness)
— Loss of descending inhibition
— Spastic paresis / paralysis
— Spinal reflexes: normal or increased
— Increased muscle tone
— Disuse muscle atrophy
— Usually associated to proprioceptive ataxia

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10
Q

LMN lesion clinical signs

A

— Paresis (weakness)
— Flaccid paresis / paralysis
— Spinal reflexes: decreased / absent
— Decreased muscle tone
— Neurogenic muscle atrophy

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11
Q

LMNs for limbs are in what regions

A

◦ Thoracic limbs: C6-T2 (cervical intumescence) ◦ Pelvic limbs: L4-S3 (lumbosacral intumescence)

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12
Q

Lesion localization: Spinal cord
— Functional classification: (segments)

A

– C1-C5
– C6-T2
– T3-L3
– L4-S3

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13
Q

C1-C5 lesion signs

A

◦ Tetraparesis / tetraplegia
◦ Proprioceptive def 4 limbs
◦ UMN deficit for 4 limbs (spastic)
◦ Reflexes: normal/increased

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14
Q

C6-T2 lesion signs

A

◦ Tetraparesis / tetraplegia
◦ Proprioceptive def 4 limbs
◦ LMN deficit TLs (flaccid):
> Decreased/absent reflexes TLs
◦ UMN deficit PLs (spastic):
> Normal/increased reflexes PLs

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15
Q

T3-L3 lesion signs

A

◦ Paraparesis / paraplegia
◦ Normal TLs
◦ Proprioceptive def PLs
◦ UMN deficit PLs (spastic)
◦ Reflexes PLs: normal/increased

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16
Q

L4-S3 lesion signs

A
  • Paraparesis / Paraplegia
  • Normal TLs
  • Proprioceptive def PLs
  • LMN deficit PLs (flaccid)
  • Reflexes PLs: decreased /absent
17
Q

Classification or myelopathies
Lesion localization

A

— Extradural
— Intradural-extramedullary
— Intramedullary

18
Q

Clinical signs spinal cord compression
- order that signs appear?

A
  1. Back/neck pain
  2. Proprioceptive ataxia / deficits
  3. Paresis
  4. Paralysis, incontinence
  5. Loss of nociception
    <><><><>
    improve in opposite direction
19
Q

important rule out for neurodisease when we see weakness, pain

A

IMPORTANT! Rule out orthopedic disease
(bilateral cruciate rupture, long bone fractures, polyarthritis)

20
Q

acute causes of myelopathies

A
  • FCEM
  • Spinal trauma
  • Intervertebral disc herniation (IVDH): extrusion
21
Q

intervertebral disc anatomy

A

a. Annulus fibrosus > outer layers
> type I collagen surrounding the nucleus pulposus in approximately 15-20 layer
b. Nucleus pulposus > inner, gelatinous material

22
Q

Intervertebral disc herniation type

A

Extrusion - acute: nucleus pulosus breaks though annulus fibrosus, impinges on spinal cord
<><>
Protrusion - chronic: annulus collagen over the years loses its consistency and the disc slowly loses its shape and impinges on the spinal cord

23
Q

IVDH: extrusion
- pathogenesis

A

— Chondroid degeneration nucleus pulposus
> (nucleus pulposus) becomes hard
– HANSEN TYPE 1 DEGENERATION
— Extrusion of mineralized nucleus pulposus into the vertebral canal

24
Q

IVDH extrusion:
clinical signs
who gets this?
location?

A

— Acute, progressive
— Chondrodystrophic breeds (small breeds)
◦ Dachshund, Beagle, Cocker Spaniel, Shih tzu…
◦ But may occur in any breed!
<><>
— Age
◦ Peak 3-6 years-old (rare < 2y)
<><><>
Location:
◦ Caudal thoracic-lumbar: T11-L3 (T12-13,T13-L1)
◦ Cervical
◦ Very uncommon T1-T10 > Intercapital ligament stabilizes

25
Q

IVDH extrusion: clinical signs
- severity depends on what?

A
  1. Location
    – Thoraco-lumbar often more severe than cervical
    – Paraparesis / paraplegia vs only cervical pain – Less epidural space TL vs cervical spinal canal
  2. Intensity, size, onset, and time since extrusion
26
Q

IVDH extrusion: diagnosis

A

— Spinal radiographs: very limited information
— Myelogram
— CT, CT-myelogram
— MRI > good for viewing soft tissue

27
Q

IVDH extrusion: treatment options, indications? when is it an emergency? success rate?

A

— Surgical vs conservative (medical)
<><><>
Surgical:
- manually remove compressive material
◦ Decompressive techniques
◦ Thoraco-lumbar: Hemilaminectomy, pediculectomy
◦ Cervical: Ventral slot
<><><><>
Indications surgical treatment:
– Severe or recurrent pain
– Neurological deficits
<><><><>
SURGICAL EMERGENCY:
◦ Absent deep pain
◦ Obvious quick deterioration
◦ Cervical:Tetraplegia
◦ Thoraco-lumbar: Non-ambulatory
<><><><>
Conservative:
1. FOCUS:
– Strict cage confinement: 3-4 weeks
2. Combined or not with Pain killers:
– Opioids, NSAIDs, steroids
3. Indications:
– First episode of pain without deficits (or mild)
4. Success: 50%; common recurrences

28
Q

IVDH extrusion: treatment 0 what should we not do?

A
  1. NEVER NSAIDs + Steroids!
  2. NEVER anti-inflammatory without cage rest:
    > Increase activity - more pressure disc - more extrusion
    <><>
    Steroids in acute spinal cord injury? > controversial
29
Q

IVDH extrusion: prognosis

A

Depends on presence of deep pain as in any spinal cord injury.
◦ Deep pain:
– Present: > 90% chances
– Absent: Guarded to poor (≤ 50%?)

30
Q

Fibrocartilaginous embolic myelopathy
- how can it arise?

A

Vascular disease: Infarct
– Spinal cord ischemia
– Embolism spinal cord vessel
<><>
Embolus:
– Identical to nucleus pulposus
– Theories entry disc material into spinal cord vascular system
<><><><>
artery or vein in spainal cord is block by fibrinocartilaginous material
> histologically looks like nucelus pulposis, but we dont know for sure what is going on here

31
Q

FCEM:
- breeds?
- history?
- locations?

A

Breed:
◦ Non-chondrodystrophic large breed dogs
◦ Miniature Schnauzer
<><>
History
◦ Crying out during mild exercise or traumatic event just before
<><>
Thoracolumbar vs cervical

32
Q

FCEM: Clinical signs

A

Presentation:
◦ Acute / hyperacute onset
◦ Non-progressive
<><>
— Asymmetrical CS > due to the fact that an infarct on the eg. left side will only affect left side of spinal cord
— Non-painful

33
Q

FCEM: Diagnosis

A

— History, signalment, clinical signs
— Rule-out other myelopathies
<><>
MRI
◦ Intramedullary
◦ Focal
◦ Asymmetrical

34
Q

FCEM
- Treatment, prognosis

A

Treatment:
- Supportive therapy
- Physical therapy
<><>
Prognosis:
◦ Deep pain presence = better prognosis
◦ Many recover function…but not completely
◦ Better if some recovery within 2 weeks

3. Cat & Dog 3 (26 decks)

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