neuro TL and spinal fractures articles

Question 1

Aikawa T et al vet Surg 2012

Recurrent TL IVD extrusion after hemilam and prophy fenestration

Answer 1

662 chondrodystrophic dogs
2.3% confirmed 2nd disc
26x's more likely at non fenest.
8 at neighbor site
6 at distal site

Question 2

Roach WJ et.al Residual herniated disc material following hemilaminectomy in chondrodystrophic dogs with thoracolumbar intervertebral disc disease. Vet Comp Orthop Traumatol. 2012;25(2):109–15

Answer 2

• 40 dogs with acute IVDD and CT scan immediately preop and postop
  
  • ALL dogs had residual disc material (or hemorrhage – it was noncontrast CT after hemilaminectomy
  • mean amount of disc (or hemorrhage) volume left behind = 50%
  • mean amount of canal area taken by residual disk (or hemorrhage) at worst slice: 30%
  • all dogs ambulatory at follow-up

Question 3

Bergknut N, Egenvall A, Hagman R, Gustås P, Hazewinkel HAW, Meij BP, et al. Incidence of intervertebral disk degeneration-related diseases and associated mortality rates in dogs. J Am Vet Med Assoc. 2012 Jun 1;240(11):1300–9

Answer 3

• 600,000 swedish dogs
• Most at risk for degenerative IVDD (anywhere in spine):
  
  • Miniature Dachshund all time highest. Lifetime prevalence = 20%
  • Standard Dachshund #2
  • Doberman #3
• GSD was most at risk for lumbosacral IVDD (and Dobie for cervical IVDD)
  
  • males > females
  • overall fatality from the disease = 34%
    
    • Dobies and GSDs: 63-65%
    • Dachshunds: 25%

Question 4

Aprea F, Cherubini GB, Palus V, Vettorato E, Corletto F. Effect of extradurally administered morphine on postoperative analgesia in dogs undergoing surgery for thoracolumbar intervertebral disk extrusion. J Am Vet Med Assoc. 2012 Sep 15;241(6):754–9

Answer 4

Dogs benefited from intraoperative splash of PF morphine onto dura after hemilaminectomy

Question 5

Hernia recurrence
1 according to Tobias
2 according to recent literature

Answer 5

1 ~20-40% most within 4 yrs. Opacified disks in non wiener dogs = 1.4x’s risk per disk. So 5 or 6 disks = 50%
2 Aikawa 2.3%, Brisson 12.7% overall,

Question 6

Muguet-Chanoit AC, Olby NJ, Lim JH, Gallagher R, Niman Z, Dillard S, et al. The Cutaneous Trunci Muscle Reflex: A Predictor of Recovery in Dogs with Acute Thoracolumbar Myelopathies Caused by Intervertebral Disc Extrusions. Vet Surg. 2012.

Answer 6

• paraplegic, no deep preop
  
  • caudal movement of CT (n=19) by discharge = 9.6 x more likely to improve (but caudal movement of CT was not associated with long term success i.e. ambulatory long term)
  • caudal movement of CT = 0% chance of myelomalacia
  • cranial movement of CT (n=6) were 145x more likely to get myelomalacia

Question 7

Bos AS, Brisson BA, Nykamp SG, Poma R, Foster RA. Accuracy, intermethod agreement, and inter-reviewer agreement for use of magnetic resonance imaging and myelography in small-breed dogs with naturally occurring first-time intervertebral disk extrusion. J Am Vet Med Assoc. 2012 Apr 15;240(8):969–77.

Answer 7

• MRI vs plain myelograms in chondrodystrophic IVDD – surgical gold standard
  
  • MRI 100 % accurate for site and side
  • myelography 91% accurate for site and 55% accurate for side

Question 8

Whats the limit of CSF you can collect?

Answer 8

No more than 1ml/5kg

Question 9

Where should you collect CSF and why?

Answer 9

From a site caudal to suspect lesion because it flow in a primarily rostrocaudal direction

Question 10

What can cause xanthochromia?

Answer 10

It’s from blood pigment (like Hgb)
Suggests previous subarachnoid hemorrhage (in absence of hyperbilirubineria)
Severe central nervous sys inflammation

Question 11

What is the genetic finding that suggests increased risk for degenerative myelopathy?

Answer 11

Homozygous for a missense mutation (G to A) in the superoxide dismutase (SOD1) gene

Question 12

Once steroid responsive meningitis-arteritis has been confirmed what blood test can you run in lieu of CSF taps to monitor therapy

Answer 12

C-reactive protein serum concentrations

Question 13

Most common concurrent condition in dogs with discospondylitis?

Answer 13

UTI

Question 14

Organisms most commonly associated with discospondylitis?

Answer 14

Staphylococcus, E.coli, Brucells, Strepotococcus, Kelbsiella, Pseudomonas, Proteus, Actinomyces

Question 15

Three cultures you should consider to help id the organism in discospondylitis

Answer 15

Blood and Urine - ~40% or better got answer in one study

Percutaneous FNA in humans ~60% got an answer

Question 16

Where does an FCE come from

Answer 16

Generally accepted it comes from nucleus pulposus

Question 17

How long should you give an FCE to improve before giving up?

Answer 17

At least 2 weeks

Recent study – voluntary by 6 days, unassisted ambulation by 11 days and max recovery by 3.75 months

Question 18

Could MRI help with FCE prognosis? If so how?

Answer 18

Maybe.
Lesion to length ratio T2 wtd L2, C6
> 2 58% an unsuccessful outcome

Question 19

What are the Pfirrmann grades:

Answer 19

Grading system for IVD on MRI (T2-wtd)

    1: homogenous and white, clear distinction, normal space size
2: nonhomogenous, clear distinction, normal space size
3: nonhomogenous and grey, indistinct, normal size
4: nonhomogenous and grey to black, no distinction, normal to decreased size
5: nonhomogenous, black, no distinction, collapsed disc space

Question 20

Witsberger TH, et al. Associations between cerebrospinal fluid biomarkers and long-term neurologic outcome in dogs with acute intervertebral disk herniation. J Am Vet Med Assoc. 2012 Mar 1;240(5):555–62

Answer 20

• CSF, from cerebromedullary cistern only
  Affected dogs
  
  • if CSF CK =/38
    
    • if CSF MBP =/

Question 21

Describe the Modified Frankel score

Answer 21

Grade 5 paraspinal hyperesthesia only
4 ambulatory paraparesis and ataxia
3 non-ambulatory paraparesis
2 paraplegic with intact nociception
1 paraplegic with no supf nociception
0 paraplegic with no deep nociception

Question 22

According to Tobias what prognosis for TL type I IVDD?

Answer 22

Deep pain positive
-ambulatory and only painful = 24/25 improved
-72-100%
-w out motor = 86-96% walking in ~3months
Deep pain NEGATIVE
- return to amublation in 43-62%
- probably low end or worse if went DP neg in less than 1 hour
-mean time to walking ~7.5 weeks, more likley to have intermittent fecal incontinence (~40%, 11% severe) and mild urinary incontinence (32%) from Olby study

Question 23

According to Tobias aside from nociception what are other prognostic indicators

Answer 23

spinal cord swelling on myelogram and T2-weighted hyper intensity on MRI greater then 5x’s the length of L2 are negative indicators

Question 24

Phenoxybenzamine

Answer 24

• Alph-adrenergic antagonist used to decrease urethral tone
• Slow therapeutic onset (may take days)
• May cause hypotension (attenuates catecholamine induced vasoconstriction via alpha 1 block)
• Less alpha 1 specific than prazosin so more likely to get tachycardia (presynaptic alpha-2 blockade of cardiac sympathetic nerves)

Question 25

Prazosin

Answer 25

• Alph-adrenergic antagonist used to decrease urethral tone
• More rapid onset than phenoxybenzamine
• May cause hypotension (attenuates catecholamine induced vasoconstriction via alpha 1 block)
• Tachycardia unlikley

Question 26

Bethanechol

Answer 26

Cholinergic muscarinic agonist (parasympathomimetic)
Increases detrusor muscle tone
Side effects - SLUD

Question 27

Funkquist A

Answer 27

• A dorsal laminectomy procedure
• zygapophyseal joints (articular facets) and pedicles are removed along with dorsal spinous process and dorsal lamina
• Maximum exposure of the spinal canal

Question 28

Funkquist B

Answer 28

Leave the articular processes (zygaphophyseal joint)

Question 29

Modified dorsal

Answer 29

Caudal zygapophyseal joint removed, preserving the cranial, but the pedicle is undercut when doing the dorsal laminectomy

Question 30

With respect to the spinal cord and the dorsal longitudinal ligament - where does the intercapital ligament lie?
What vertebrae does the intercapital ligament reside

Answer 30

It lies dorsal to the spinal cord and ventral to the dorsal longitudinal ligament from T2-T11

Question 31

What is respiratory issues associated with cervical fractures attributed too (according to Tobias)

Answer 31

2 possibilities - disruption of
Intercostal innervation (T4 nerve roots)
Diaphragm innervation phrenic nn (C3-C5)

Question 32

Safe corridors for screws in cervical bones per Tobias

C3-C6

Answer 32

C3-C6 = BEWARE the transverse foramen.
Bicortical screws start at midline of the caudal ventral aspect and direct 34.2-37.5 degrees from the sagittal plane and parallel to the transverse plane
Monocoritical srews start midway between midline and the bulge of the transverse foramen at the caudal border and go straight in.
(best is to base on CT of patient)

Question 33

Safe corridors for C7

Answer 33

No transverse foramen so bigger angle and less scary

Avg reported is 47.5 degrees

Question 34

Safe corridors for C2

Answer 34

C2 has a thin central body so don’t use
Cranially stability improved if cross AA joint so start in cranial part of C2 and direct craniolaterally 30-35 degrees from sagittal plane and 40-45 degrees from transverse plane. Shoot for medial aspect of alar notch in C1
Caudal pins pointed laterally 30-50 degrees within the transverse plane.
If have a caudal body fracture then go to C3 for caudal anchor points

Question 35

Entry point and safe corridors for T10-T13

Answer 35

Entry point level of the accessory process or the tubercle of the rib 30(ideal) 50 (max safe) from the sagittal plane.
Higher risk if penetrate ventral cortex too far (bleeding, pneuma etc)

Question 36

Entry points and safe corridors for
L1-5
L6-L7

Answer 36

Entry - between base of transverse process and accessory process
L1-5 = 25 (ideal) 50 (max safe)
L6-7 = 35 and 40
(L7 has wide pedicle that you can shoot straight into - although Smolders 2012 LSI stabilization paper would beg to differ)

Question 37

Jeffery, ND et.al. JAVMA 2016. Factors associated with recovery from paraplegia in dogs with loss of pain in the pelvic limbs following IVD herniation

Answer 37

No factor evaluated had prognostic value
Looked at -
duration of clinical signs prior to paraplegia
delay of onset to referral evaluation, date of recovery of locomotion, death or euthanisia
Did dog get steroid before surgery
Severity of spinal cord compression

Question 38

Noussitou, FL et.al. VetSurg2015 Assessment of intramedullary spinal pressure in small breed dogs with TL disk extrusion undergoing helium

Answer 38

IMP in increased and its decreased immediately with surgery.
No correlation between IMP and neurologic grade, degree of spinal cord compression or signal changes on MRI