32. TL spine

Question 1

articular process joints are also referred to as

Answer 1

zygapophyseal jointsamphiarthrodial (slight motion contain synovial fluid)less prominent in cranial thoracic spine (T10) and more prominent caudally

Question 2

what muscle attaches to accessory processes of the TL spine

Answer 2

longissimus lumborum

Question 3

define anticlinal vertebrae

Answer 3

T11cranial thoracic vertebra spinous processes slant caudallywhere as T11-T13 slant dorsal or cranially

Question 4

three components of the intervertebral disc

Answer 4

1. annulus fibrosis (concentric collagen)2. nucleus pulposis (remnant notochord, hydrated, contains glycosaminoglycan, IV collagen)3. cartilaginous endplate (allows nutrient entry to the avascular disc)

Question 5

3 long and 4 short ligaments of the spine include:

Answer 5

long1. supraspinous ligament 2. dorsal longitudinal lig3. ventral longitudinal ligshort1. intraspinous lig2. intratransverse lig3. yellow ligament/interarcuate ligament4. intercapital lig (under dorsal longitudinal lig from rib to rib–makes cranial to T11 IVDD rare)

Question 6

endogenous biomechanics stability of vertebral column (not including ligaments)

Answer 6

1. zygapophyseal joints2. disc space3. muscle tendon units

Question 7

ways to ensure correct location in spinal surgery

Answer 7

1. palpate landmarks (last first, L1 transverse process, sacrum, anticlinal T11)2. inject methylene blue under radiographic guidance3. marker needle placed with radiographic or fluoroscopic guidance

Question 8

arterial and venous blood supply to TL spine

Answer 8

spinal branches of intercostal arteriesinternal vertebral sinus (ventrolaterally on floor of canal) drains

Question 9

surgical procedures for TL spine disc removal

Answer 9

–dorsal or dorsolateral approach for dorsal laminectomy–hemilaminectomy–mini hemilaminectomy (meant to preserve jt)–disc fenestration (NOT alone)–lateral corpectomy (chronic discs)–pediculectomy (meant to preserve jt–performed when compression is over the body)–percutaneous discectomy (wire, trephine into disc)–vertebral realignment and stabilization

Question 10

muscle elevated after incision dorsal thoracolumbar fascia during routine TL dorsal approach to spine

Answer 10

multifidus musculaturetendon isolated on articular process/zygapophyseal jt and cut

Question 11

why is accessory process an important landmark in spinal surgery

Answer 11

indicates the ventral aspect of the spinal canal

Question 12

2 complications associated with lateral approach to spinal cord for lateral disc fenestration

Answer 12

1. entry into body cavity (Ab or chest) and proximity of aorta2. injury to spinal nerve (cranial to disc space)

Question 13

difference in dorsolateral approach vs dorsal approach to spine

Answer 13

dorsal: elevate multifius musculature and transect from articular processdorsolateral: blunt dissection to find seperation btwn multifidus (medial) and longissimus (lateral) muscles and go btwn muscles

Question 14

biomechanical forces acting on the spine and 3 major portion of the spine

Answer 14

1. vertebral body–buttress; resists axial compression and bending2. articular process–resists all forces3. intervertebral disc–resists rotation and lateral bendingcompromises >2 components (especially bilaterally) may require stabilization

Question 15

anatomic landmarks outlining the hemilaminectomy defect

Answer 15

–ventral aspect of accessory process (ventral)–base of spinous process (dorsal)–base of articular process cranial and caudal to defect (cr-cd extent)

Question 16

types of dorsal laminectomy

Answer 16

Funkquist A: spinous process, lamina, articular processes, half of the pedicles (MOST EXPOSURE)Funkquist B: spinous process, lamina (LEAVES ARTICULAR PROCESSES INTACT)Modified version: spinous process, lamina, CAUDAL articular process, pedicle is UNDERCUT to gain access to ventral spinal canal (MOST ARTICULAR PROCESS INTACT)Deep: spinous process, lamina, accessory processes and pedicles up to ventral spinal canalAlt to Funkquist: osteotomy of spinous process

Question 17

complications with disc fenestration

Answer 17

1. discospondylitis2. injury to spinal nerve3. pneumothorax4. hemorrhage5. spinal instability6. +/- recurrence of herniation

Question 18

accuracy of radiographs to determine presence of single site disc herniation

Answer 18

51-61%therefore use radiographs for screening tool to R/O fracture, lux/sublux, discospondylitis, large osseous changes/masses

Question 19

radiographic features supportive of IVDD

Answer 19

–narrowing disc space **highest SN–increased radio opacity in intervertebral foramen–decreased intervertebral foramen size/diameter–increased radio opacity in spinal canal–wedge disc space–increased articular process overlap–vacuum phenomenon (gas within disc space–not common)

Question 20

accuracy of myelogram to determine correct site and side of disc herniation

Answer 20

85.7-98% site89-100% side(does not allow imaging of spinal cord but can ID extradural compression, or IM pattern with spinal cord edema/hemorrhage)

Question 21

prognostic information gained on myelogram for deep pain negative dogs

Answer 21

lesion: length L2 ratio > 5animals with an intramedullary pattern (indicating spinal edema)/L2 length ratio > 5 had a 26% recoveryvs 61% recovery for ratios < 5ANY intraparenchymal uptake of contrast is BAD–gaurded 6/7 dogs ascending-descending myelomalacia

Question 22

adverse events associated with myelogram

Answer 22

–seizures 10-21% (bigger, heavier dogs, cisterna injections)–myelopathy/meningitis–subarachnoid hemorrhage–cardiac arrhythmias and death–artifacts (“canalogram”, subdural filling)

Question 23

accuracy of CT to determine correct site and side of disc herniation

Answer 23

95-100% site96% side

Question 24

disc material intensity on MRI

Answer 24

should NORMALLY be hydrated/fluid likeT1–hypointenseT2–hyperintensechondrodystrophic breedsT1–variableT2–hypointense/variable (bc dehydrated)

Question 25

% diagnosis of FCE on MRI

Answer 25

78.8%

Question 26

prognostic information gained on MRI for return to ambulation in IVDD patients

Answer 26

T2 parenchymal signal intensity lesion: length L2 ratiolack signal intensity–all return to voluntary motor >3 only 20% return to voluntary motorodds of recovery reduced 1.9 fold PER UNIT of hyper intensity seenalso highly sensitive for evaluated type 3 IVDD patients (poor px if parenchymal hyper intensity)

Question 27

T/Flumbar cisterna CSF taps contain more lymphocytes and are more prone to iatrogenic blood contamination

Answer 27

TRUE

Question 28

medical mgmt leads to success in what percentage of ambulatory vs non ambulatory dogs

Answer 28

success in 82-88% that were ambulatorysuccess only in 43-51% that were nonambulatory

Question 29

recurrence of pain, ataxia, weakness in medically treated dogs

Answer 29

31% (can be as high as 40%)

Question 30

T/Fmultiple continuous hemilam (up to 3 unilateral or 2 bilateral) did not change stability of spine in extreme flexion/extension

Answer 30

TRUE(Corse, Renberg et al AJVR 2003)multiple continuous hemilam (up to 3 unilateral or 2 bilateral) did not change stability of spine in extreme flexion/extension in cadaveric study of LUMBAR vertebra of NONchondrodystrophic breedsup to 7 continuous unilateral have been reported without consequences

Question 31

T/Fdisc fenestration of cervical spine in cadaver model did demonstrate significant instability vs nonfenestrated spine

Answer 31

TRUEdisc fenestration of cervical spine in cadaver model did demonstrate significant instability vs nonfenestrated spine

Question 32

success with surgery in IVDD dogs with intact pain perception

Answer 32

72-100%

Question 33

success with surgery in IVDD dogs WITHOUT intact pain perception

Answer 33

43-62%dogs operated earlier (24 hr within loss of nociception) may have a better pxdogs that regain deep pain within 2 weeks have a good px

Question 34

myelogram and MRI negative prognostic indicators for IVDD dogs that lack deep pain

Answer 34

Negative prognostic indicatorslesion: L2 length > 5 (myelogram)T2 weighted intraparenchymal hyper intensity (MRI)

Question 35

Olby and Levin 2003 JAVMA% of deep pain negative dogs that recovered and the time until voluntary motor

Answer 35

58% recovered7.5 weeks until ambulatory(may still have fecal incontinence 40%, may still have urinary incontinence 32%)

Question 36

factor NOT associated with outcome in patients with IVDD

Answer 36

–location

Question 37

define rhizotomy

Answer 37

severance of nerve root (as long as it is not part of lumbar plexus)done to increase exposureavoided bc body wall weakness occurs

Question 38

Mayhew et al 2004 JAVMA229 IVDD dogs followed out for 3.7 yearsrate of recurrence

Answer 38

No fenestration performed20% recurrence within 3 years of surgery

Question 39

laser disc ablation as an alternative to prophylactic disc fenestration

Answer 39

percutaneous approachT10-L4Holmium:yttrium-aluminum-garnet (Ho:YAG) laser to ablatecomplications: pneumothorax, abscessation at percutaneous needle site, discospondylitits, worsening neuro signs

Question 40

nerves involved in micturition

Answer 40

SNS: STORAGE–hypogastric (L1-4)B: INACTIVE, relaxes detrusor m–hypogastric alpha: ACTIVE, closes internal urethral sphincter–hypogastric INHIBITS pelvic nerve/ganglia during storagePSNS: PEEING–pelvic n (S1-3): ACTIVE (senses stretch)–hypogastric B: ACTIVE contract detrusor m–hypogastric alpha: INACTIVE, relax internal urethral sphincterSOMATIC (VOLUNTARY CONTROL)–pudendal n: (S1-S3) external urethral sphincter

Question 41

alpha adrenergic antagonists

Answer 41

rapid onset===prazosin 1 mg/15 kg PO q8-24 hrslow onset===phenoxybenzamine 0.25-0.5 mg/kg PO q12-24hrside effect: hypotension+/- bethanocol if bladder atony but give alpha antagonist FIRST

Question 42

Bubenik Vet Sx 2008what conclusion from method of bladder evacuation and risk of bacterial UTI

Answer 42

DURATION for need of bladder evacuation NOT THE METHOD (catheter vs expression) increased the risk of bacterial UTIGENDER was NOT a risk factorssuggest avoiding prophy Ab

Question 43

US assessment for adequate post void bladder size

Answer 43

< 30 kg patient 3 cm> 30 kg patient 4-5 cm

Question 44

list congenital/developmental malformations of the TL spine

Answer 44

–hemivertebra, block vertebra, butterfly vertebra–spina bifida–cartilaginous exostoses (osteochondromatosis–BENIGN)-dermoid sinus (pilonidal sinus)–epidermal cysts–spinal arachnoid diverticula (subarachnoid cysts)–spinal dysraphism(weimaraner)–tumoral calcinosis–leukodystrophy