neuro TL and spinal fractures articles Flashcards
Aikawa T et al vet Surg 2012
Recurrent TL IVD extrusion after hemilam and prophy fenestration
662 chondrodystrophic dogs 2.3% confirmed 2nd disc 26x's more likely at non fenest. 8 at neighbor site 6 at distal site
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
- 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
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
- 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%
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
Dogs benefited from intraoperative splash of PF morphine onto dura after hemilaminectomy
Hernia recurrence
1 according to Tobias
2 according to recent literature
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,
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.
- 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
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.
- 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
Whats the limit of CSF you can collect?
No more than 1ml/5kg
Where should you collect CSF and why?
From a site caudal to suspect lesion because it flow in a primarily rostrocaudal direction
What can cause xanthochromia?
It’s from blood pigment (like Hgb)
Suggests previous subarachnoid hemorrhage (in absence of hyperbilirubineria)
Severe central nervous sys inflammation
What is the genetic finding that suggests increased risk for degenerative myelopathy?
Homozygous for a missense mutation (G to A) in the superoxide dismutase (SOD1) gene
Once steroid responsive meningitis-arteritis has been confirmed what blood test can you run in lieu of CSF taps to monitor therapy
C-reactive protein serum concentrations
Most common concurrent condition in dogs with discospondylitis?
UTI
Organisms most commonly associated with discospondylitis?
Staphylococcus, E.coli, Brucells, Strepotococcus, Kelbsiella, Pseudomonas, Proteus, Actinomyces
Three cultures you should consider to help id the organism in discospondylitis
Blood and Urine - ~40% or better got answer in one study
Percutaneous FNA in humans ~60% got an answer
Where does an FCE come from
Generally accepted it comes from nucleus pulposus
How long should you give an FCE to improve before giving up?
At least 2 weeks
Recent study – voluntary by 6 days, unassisted ambulation by 11 days and max recovery by 3.75 months
Could MRI help with FCE prognosis? If so how?
Maybe.
Lesion to length ratio T2 wtd L2, C6
> 2 58% an unsuccessful outcome
What are the Pfirrmann grades:
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
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
- CSF, from cerebromedullary cistern only
Affected dogs- if CSF CK =/38
- if CSF MBP =/
- if CSF CK =/38
Describe the Modified Frankel score
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
According to Tobias what prognosis for TL type I IVDD?
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
According to Tobias aside from nociception what are other prognostic indicators
spinal cord swelling on myelogram and T2-weighted hyper intensity on MRI greater then 5x’s the length of L2 are negative indicators
Phenoxybenzamine
- 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)
Prazosin
- 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
Bethanechol
Cholinergic muscarinic agonist (parasympathomimetic)
Increases detrusor muscle tone
Side effects - SLUD
Funkquist A
- 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
Funkquist B
Leave the articular processes (zygaphophyseal joint)
Modified dorsal
Caudal zygapophyseal joint removed, preserving the cranial, but the pedicle is undercut when doing the dorsal laminectomy
With respect to the spinal cord and the dorsal longitudinal ligament - where does the intercapital ligament lie?
What vertebrae does the intercapital ligament reside
It lies dorsal to the spinal cord and ventral to the dorsal longitudinal ligament from T2-T11
What is respiratory issues associated with cervical fractures attributed too (according to Tobias)
2 possibilities - disruption of
Intercostal innervation (T4 nerve roots)
Diaphragm innervation phrenic nn (C3-C5)
Safe corridors for screws in cervical bones per Tobias
C3-C6
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)
Safe corridors for C7
No transverse foramen so bigger angle and less scary
Avg reported is 47.5 degrees
Safe corridors for C2
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
Entry point and safe corridors for T10-T13
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)
Entry points and safe corridors for
L1-5
L6-L7
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)
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
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
Noussitou, FL et.al. VetSurg2015 Assessment of intramedullary spinal pressure in small breed dogs with TL disk extrusion undergoing helium
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
