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Tobias ECVS - Krizia > Ch 31 - Cervical Vertebral Column and Spinal Cord > Flashcards

Ch 31 - Cervical Vertebral Column and Spinal Cord Flashcards

1
Q

What CN deficits can be seen with a C1-C5 lesion?

A

Positional strabysmus and/or facial hyperaesthesia with C1-C3
v. rare!

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2
Q

Damage to what nerve roots can cause Horners syndrome?

A

T1-T3

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3
Q

What does paresis or paralysis indicated?

A
  • A disease process affecting the descending UMN tracts
  • Or a diffuse neuromuscular disease
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4
Q

Why do dogs with cervical lesions often present with more pronounced motor dysfunction in the pelvic limbs?

A

The descending UMN tracts to the pelvic limbs are more peripherally located within the spinal cord

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5
Q

What percentage of tetraparetic dogs are incorrectly localaised based on the FL withdrawal?

A

34%

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6
Q

How quickly does neurogenic atrophy become clinically obvious? Disuse atrophy?

A
  • Neurogenic wtihin 7 days
  • Disuse will take several weeks
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7
Q

What is a transverse myelopathy?

A

No transmission of ascending or descending impulses across the site of the lesion

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8
Q

What is Horners Syndrome?
What spinal cord segment can cause this?
What is the path of the sympathetic nerves?

A
  • Horners syndrome is loos of sympathetic innervation to the eye causing miosis, ptosis, enophthalmos and elevation of the third eyelid
  • T1-T3
  • Hypothalamus -> descends sp. cord in lateral tectotegmental tracts
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9
Q

What are the advantages of the modified ventral approach to the cervical spine?

A
  • Helps to protect the trachea, right recurrent laryngeal nerve and right carotid sheath
  • Provided increased exposure of the caudal cervical vertebrae
  • Decreases risk of haemorrhage from right caudal thyroid artery
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10
Q

What are the benefits of the right parasagittal approach for the ventral approach to the AA joint?

A
  • Improved exposure of the joint
  • Avoids dissection around the thyroid gland, trachea and recurrent laryngeal nerve
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11
Q

What surgical landmark can be used for ventral C1-C2

A

Pointed ventral prominence (ventral tubercle) on the caudal aspect of C1. This indicates the ventral midline of C1-C2 joint space

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12
Q

What is a lateral approach to the cervical spine good for?

A

Lateral or foraminal IVD herniation and nerve sheath neoplasms

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13
Q

What muscles required dissection for the lateral approach to C1-C4?

How does this differ for C5-C7?

A
  • Platysma
  • Blunt seperation through brachiocephalicus
  • Splenius
  • Serratus vantralis
  • Plane of dissection between longissimus capitus and complexus muscles to expose articular facet
  • Dorsal branch of the spinal nerve needs to be sacrificed, the tendinous attachments of the complexus and multifidus are then detached from the articular process
  • Longissimus capitus sharply dissected from transverse process and reflected ventrally to fully expose the joints

C5-C7 requires seperation of brachiocephalicus from trapezium (not dissection through). The superficial cervical artery and vein will be located between these muscles and is ligated

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14
Q

What retractor can be used to retract the scapula on approach to the brachial plexus?

A

Farabeuf retractor

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15
Q

What muscle do the spinal nerves of the brachial plexus lie deep to?

A

Scalenus muscle

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16
Q

What joint is considered the yes joint?
And the no joint?

A
  • Yes joint - occipitoatlas joint
  • No joint - atlantoaxial joint
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17
Q

How many pairs of foramina does the atlas have?

A

Two
- Transverse foramen - passes obliquely through transverse process
- Lateral vertebral foramen - perforates the craniodorsal part of the vertebral dorsal arch. First cervical spinal nerve and its associated vasculature run through here

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18
Q

What are the atlantal fossae?

A

Depressions ventral to the wings on each side where the vertebral vein and artery run

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19
Q

How many bony elements for the atlas and axis develop from?
How long does it take for fusion?

A
  • Atlas - 3 boney elements
  • Axis - 7 boney elements (pair of arches, 3 parts of the body, the dens, apical elements of the dens)
  • Fusion of dorsal atlas by 106d, ventral suture by 115d
  • Fusion of all parts of axis from 30 - 396d
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20
Q

What is another name for the dens?

A

Odontoid process

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21
Q

List the stabilising ligaments of the AA joint

A
  • Transverse ligament - holds the dens within the ventral aspect of the vertebral foramen. Prevents dorsal movement which allowing rotation
  • Apical ligament - attachs dens to basioccipital bone
  • Bilateral alar ligaments - Attach dens to the occipital condyles
  • Dorsal atlantoaxial ligament - Joins dorsal arch of atlas to craniodorsal spine of axis

Alar ligaments provide the most important stabilisation against VD shearing forces

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22
Q

List possible congenital or developmental abnormalities of the AA joint

A
  • Dysplasia (34%)
  • Hypoplasia or aplasia (46%)
  • Dorsal angulation of the dens
  • Seperation of the dens
  • Absense of the transverse ligament
  • Incomplete ossification of the atlas
  • Block vertebrae
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23
Q

What percentage of dogs with AA sublux will have a normal dens?

A

24%

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24
Q

What breeds are predisposed to congenital abnormalities predisposing to AA instability?

A
  • Yorkies
  • Chihuahuas
  • Min Poodles
  • Poms
  • Pekingese

Standard Poodles! - inherited ansense/hypoplasia of the dens

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25
Q

What is predictive of AA instability on a plain lateral radiograph?

A

An angle between the atlas and axis of less than 162 degrees

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26
Q

What is a contraindication for dorsal stabilisation of AA sublux?
What are the advantages of ventral stabilisation?

A

Dorsal deviation of the dens
Ventral advantages:
- odontoidectomy can be performed if required
- Provides a means for bony ankylosis for permanent joint fusion (approach of choice for AA fractures)

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27
Q

List the dorsal techniques for AA stabilisation and their associated long term success rates

A
  • Atlantoaxial wiring/dorsal loop wiring - 52%
  • Double stranded cross-suturing (less than 2kg) - 50%
  • nuchal ligament technique - 75%
  • Dorsal cross-pinning
  • Kishigami AA tension band - 75%
28
Q

What is this device?
What are its advantages?

A
  • Kishigami tension band for dorsal stabilisation of AA sublux
  • Reduced risk of damaging the spinal cord as it does not need to be passed under the dorsal arch
29
Q

List the ventral stabilisation techniques for AA subluxation and their associated long-term success rates

A
  • Transarticular screws or pins - 47%
  • Pins and PMMA - 94% (long-term complications 34%)
  • Screws and PMMA (placed 30-40 degrees)
  • Ventral plating (mini H-plate 2.0mm, 5-hole butterfly plate 1.5mm)
30
Q

What is the mean optimal AA insertion angle of transarticular screw/pin insertions?

What was the mean corridor length and width?

A
  • 40+/-1 degree in medial to lateral direction
  • 20+/-1 degree in VD direction from ventral aspect of vertebral foramen of the axis

Mean corridor length 7mm, width 3-5mm

AIming in a craniolateral direction

31
Q

What is the overall rate of complications for dorsal and vental stabilisation of AA sublux?

A
  • Dorsal 71%
  • Ventral 53%

Implant failure of the transarticular pins most common complications. Implant failure 48% dorsal vs 44% ventral, may or may not require re-op

32
Q

What are the known risk factors effecting surgical outcome for AA stabilisation

A
  • Age of onset: Dogs under 24m had greater odds of successful outcome
  • Duration and severity of clinical signs: Under 10m associated with greater odds of successful outcome
33
Q

In what percentage of dogs does the C5 spinal cord segment contribute to the brachial plexus?

A

24%

34
Q

What nerves are branches of the brachial plexus?

A
  • Brachiocephalic
  • Suprascapular
  • Subscapular
  • Axillary
  • Musculocutaneous
  • Radial
  • Median
  • Ulnar
  • Dorsal thoracic
  • Lateral thoracic
  • Long thoracic
  • Pectoral
  • Muscular branches
35
Q

List the 6 classes of nerve trauma

A
  • Class 1: Neurapraxia - interruption of the function and conduction of a nerve without structural changes. Reversible, up to 6 weeks to improve
  • Class 2: Axonotmesis - crush or percussion injuries causing Wallerian degeneration. Internal architecture of the nerve, including the endoneurium and Schwann sheath is well preserved. Recovery expected but can take several weeks
  • Class 3: Neurotmesis - Disruption of axons and endoneurium but fascicular orientation is maintained by intact perineurium
  • Class 4: Neurotmesis - Disrupted perineurium
  • Class 5: Neurotmesis - Entire nerve severed
  • Class 6: COmbines several of the previouse degree of injury per fascicle
36
Q

What are the 3 forms of brachial plexua injury and their common associated signs?

A
  • Injury of the cranial portion (C5-C7) - Effects musculocutaneous, axillary, subscapular and suprascapular nerves. Loss of shoulder movement and elbow flexion, shoulder atrophy
  • Injury to the caudal potion (C8-T2) - Radial, median and ulnar nerves. Cannot extened elbow and thererfore cannot weight bear. Radial nerve involved in 92% of dogs. Can sometimes see Horners syndrome and loss of cutaneous trunci
  • Complete injury (C6-T2) - Drags leg knuckles, shoulder more ventral, hypotonic and atrophy
37
Q

WHat is indicative of a poor prognosis on EMG?

A

Early decreased radial nerve conduction velocity indicates a poor prognosis

38
Q

List the surgical techniques for brachial plexus repair

A
  • Neurotization (nerve transfer) - Can be neuroneural or neuromuscular using 9-0 monofilament nylon
  • Reimplantation via hemilaminectomy, durotomy, incision into pia mater and spinal cord

Successful neurotization in cats using right lateral thoracic and thoracodorsal nerve to reinnervate the left transected musculocutaneous nerve

39
Q

What percentage of IVDH are cervical?

A

14-25%

40
Q

What are the most common sites of cervical disc herniation in chondrodystrophic dogs?

A
  • 80% C2-C4
  • 44-59% C2-C3

Caudal disc spaces are mosre common in Yorkies and Chihuahuas as well as large breeds

41
Q

What CSF protein may serve as a prognostic indicator?

A

Microtuble-associated protein tau (positively associated with the severity of spinal cord damage)

42
Q

What is chemonucleolysis?

A

Intradiscal injection of chondroitinase ABC to treat disc herniation. 92% of dogs improved with 77% having excellent improvement

43
Q

What are the maximum sizes of a ventral slot window?

A
  • 33% length of vertebral body
  • 50% width (but preferably 33%)
44
Q

What are the advantages of a slanted slot?
What are the recommened window sizes?

A
  • Provides access at the site of herniation without removing a large portion of the annulus, thereby preserving more stability
  • Window: 20% width and 20-25% length
45
Q

What are the reported complication rates of v-slot?

A
  • 9.9% complications, 6.4% of which are major
  • Mean mortality 3-8%
  • Respiratory compromise (phrenic nerve C5-C7)
  • Cardiac dysrhythmmias
  • Haemorrhage (18.9%)
  • Neuro deterioration
  • Instability (8% when width 50%)
46
Q

What has been shown to be associated with prognosis for cervical IVDH?

A
  • Site: caudal to C3-C4 have poorer prognosis (likely included Wobblers)
  • Degree of injury: LMN dysfunction.
  • Duration of disease: Able to walk within 96hr are likely to make a full recovery, dogs that do not walk within 2 weeks are likely to have residual deficits
  • Type of Tx: 36% recurrency with conservative vs 5-10% surgical, v-slot 90% full recovery 1m and 98% vs 78% hemilam at 12m, higher complication with v-slot but longer recovery wtih slanted slot, Hansen type II good and excellent in 47% and 32%
47
Q

What anatomical differences explain the predisposition of wobblers in large dogs?

A
  • The vertebral foramen is proportionately smaller in lare dogs
  • The vertebral height of the cranial aspect of the foramen in significantly smaller than small dogs, resulting in a funnel shaped vertebral foramen
48
Q

What three factors explain the pathophysiology of cervicospondylomyelopathy?

A
  • Vertebral canal stenosis
  • Pornounced torsion of the caudal cervical column leading to IVD degeneration (caudal cervical spine has three times more torsion than cranial)
  • Protrusion of larger volume intervertebral discs
49
Q

What causes osseous compression in CSM?

A
  • Proliferation of the laminae dorsally
  • Articular processes dorsolaterally
  • Pedicles laterally
50
Q

What molecular mechanisms play a role in CSM?

A
  • Apoptosis of oligodendrocytes interfering with remyelination
  • Upregulation of alpha-2-HS and SPRAC as well as complement C3, all assoc with osteoarthritis change
  • Significant reduction in monocyte chemoattractant protein/chemokine ligand 2 (MCP-1/CCL2) concentrations - monocytes are needed for clearance of axonal and myelin debris for clearance and recovery
  • Elevation of IL6 - implicated in generation and propagation of chronic inflammation
51
Q

What are the rates of single lesions vs multiple lesions in CSM?

A
  • Large breeds: 50/50
  • Giant breeds: 20% single site, 80% multiple
52
Q

What is the rate of post-myelogram seizures in Dobermans?

A

25-27%

53
Q

What additional tests should be performed in a presurgical evaluation of a Wobblers patient, esp. if a Doberman

A
  • Thyroid function
  • von Willebrand status
  • Cardiac function
54
Q

What is the rate of improvement in conservative vs surgical treatment of CSM

A

Conservative:
- 54% improved
- 27% static

Surgery
- 81% improvement

55
Q

How are corticosteroids helpful in conservative management of CSM?

A
  • Decrease vasogenic oedema
  • Protection from glutamate toxicity
  • Reduction of apoptosis
56
Q

List the direct decompressive techniques for treatment of CSM

A
  • Ventral slot (72%)
  • Inverted cone
  • Dorsal laminectomy (79-95%, 30% recurrence)
  • Hemilaminectomy
57
Q

List the indirect decompression-distraction techniques for treatment of CSM

A
  • Pins and PMMA (73%)
  • Screw Bar-PMMA
  • PMMA plug (82%, long term 62%)
  • Locking plate (73%)
  • Distractible titanium cage
  • polyetheretherketone (PEEK) cage with locking plates
  • Traction screw with locking plates
58
Q

What is a motion-preserving technique for treating CSM?
What are the benefits?

A

Cervical Disc Arthroplasy: a technique to distract the spine while preserving moton
- Allows direct decompression
- Allows reestabishment of normal disc space with preserved motion to decrease risk of domino effect (adjacent segment disease)

59
Q

What is the recommened width of an inverted cone v-slot?
What are the proposed benefits?

A
  • 20% width of vertebral body
  • Allows more complete removal of the protruded disc
  • Less risk of haemorrhage
  • Minimised risk of IVDS collapse
60
Q

What distractors can be used for IVDS?

A
  • Caspar distractor
  • modified Gelpi distractor
61
Q

What is the recommended angle of insertion for pins when treating CSM?

A

-C5-C6 - 30-35 degrees
C7 - 45 degrees

Monocortical screws perform similarly to bicortical positive profile pins

62
Q

What are some key points in the application of a PMMA plug?
How can you reduce the rates of migration?

A
  • Discectomy, leaving approx 3-5mm of dorsal annulus intact
  • Anchor holes in the adjacent vertebral end plates
  • Bone graft into ventral disc space once PMMA has hardened
  • A retention screw can help to prevent migration
63
Q

What complications are possible with CSM treatment?

A

14.9% complication rate
- Neuro deterioration (70% after continuous dorsal laminectomy, up to 42% with ventral techniques)
- Improper implant placement (25-57%)
- Domino effect (20%)
- Laminectomy membrane?
- Implant failure (7.5-30%)
- Collapse
- Insufficient decompression
- Recurrence 24%

64
Q

What MRI findins are associated with a poorer outcome for CSM?

A

Spinal cord hyperintensity on T2W with concurrent hypointensity on T1W images

65
Q

What are extradural synovial cysts?

A

Cysts originating from the zygapophyseal joints of the vertebral articulations and are located extradurally. Divided histologically into synovial cysts (epithelial lining) and ganglion cysts (mucinous degeneration or articular cartilage)

66
Q

What is the main predisposing factor of extradural synovial cysts?

A

Degenerative changes of the zygapophyseal joint

67
Q

What are the treatment options for extradural synovial cysts?

A
  • Dorsal laminectomy
  • Hemilaminectomy
  • Percutaneous cyst rupture with corticosteroid injection (humans)

Must remove enture cyst and periarticular soft tissues to minimize risk of recurrence

Tobias ECVS - Krizia (110 decks)

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