32. TL spine Flashcards
articular process joints are also referred to as
zygapophyseal jointsamphiarthrodial (slight motion contain synovial fluid)less prominent in cranial thoracic spine (T10) and more prominent caudally
what muscle attaches to accessory processes of the TL spine
longissimus lumborum
define anticlinal vertebrae
T11cranial thoracic vertebra spinous processes slant caudallywhere as T11-T13 slant dorsal or cranially
three components of the intervertebral disc
- annulus fibrosis (concentric collagen)2. nucleus pulposis (remnant notochord, hydrated, contains glycosaminoglycan, IV collagen)3. cartilaginous endplate (allows nutrient entry to the avascular disc)
3 long and 4 short ligaments of the spine include:
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)
endogenous biomechanics stability of vertebral column (not including ligaments)
- zygapophyseal joints2. disc space3. muscle tendon units
ways to ensure correct location in spinal surgery
- 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
arterial and venous blood supply to TL spine
spinal branches of intercostal arteriesinternal vertebral sinus (ventrolaterally on floor of canal) drains
surgical procedures for TL spine disc removal
–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
muscle elevated after incision dorsal thoracolumbar fascia during routine TL dorsal approach to spine
multifidus musculaturetendon isolated on articular process/zygapophyseal jt and cut
why is accessory process an important landmark in spinal surgery
indicates the ventral aspect of the spinal canal
2 complications associated with lateral approach to spinal cord for lateral disc fenestration
- entry into body cavity (Ab or chest) and proximity of aorta2. injury to spinal nerve (cranial to disc space)
difference in dorsolateral approach vs dorsal approach to spine
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
biomechanical forces acting on the spine and 3 major portion of the spine
- 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
anatomic landmarks outlining the hemilaminectomy defect
–ventral aspect of accessory process (ventral)–base of spinous process (dorsal)–base of articular process cranial and caudal to defect (cr-cd extent)
types of dorsal laminectomy
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
complications with disc fenestration
- discospondylitis2. injury to spinal nerve3. pneumothorax4. hemorrhage5. spinal instability6. +/- recurrence of herniation
accuracy of radiographs to determine presence of single site disc herniation
51-61%therefore use radiographs for screening tool to R/O fracture, lux/sublux, discospondylitis, large osseous changes/masses
radiographic features supportive of IVDD
–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)
accuracy of myelogram to determine correct site and side of disc herniation
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)
prognostic information gained on myelogram for deep pain negative dogs
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
adverse events associated with myelogram
–seizures 10-21% (bigger, heavier dogs, cisterna injections)–myelopathy/meningitis–subarachnoid hemorrhage–cardiac arrhythmias and death–artifacts (“canalogram”, subdural filling)
accuracy of CT to determine correct site and side of disc herniation
95-100% site96% side
disc material intensity on MRI
should NORMALLY be hydrated/fluid likeT1–hypointenseT2–hyperintensechondrodystrophic breedsT1–variableT2–hypointense/variable (bc dehydrated)
% diagnosis of FCE on MRI
78.8%
prognostic information gained on MRI for return to ambulation in IVDD patients
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)
T/Flumbar cisterna CSF taps contain more lymphocytes and are more prone to iatrogenic blood contamination
TRUE
medical mgmt leads to success in what percentage of ambulatory vs non ambulatory dogs
success in 82-88% that were ambulatorysuccess only in 43-51% that were nonambulatory
recurrence of pain, ataxia, weakness in medically treated dogs
31% (can be as high as 40%)
T/Fmultiple continuous hemilam (up to 3 unilateral or 2 bilateral) did not change stability of spine in extreme flexion/extension
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
T/Fdisc fenestration of cervical spine in cadaver model did demonstrate significant instability vs nonfenestrated spine
TRUEdisc fenestration of cervical spine in cadaver model did demonstrate significant instability vs nonfenestrated spine
success with surgery in IVDD dogs with intact pain perception
72-100%
success with surgery in IVDD dogs WITHOUT intact pain perception
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
myelogram and MRI negative prognostic indicators for IVDD dogs that lack deep pain
Negative prognostic indicatorslesion: L2 length > 5 (myelogram)T2 weighted intraparenchymal hyper intensity (MRI)
Olby and Levin 2003 JAVMA% of deep pain negative dogs that recovered and the time until voluntary motor
58% recovered7.5 weeks until ambulatory(may still have fecal incontinence 40%, may still have urinary incontinence 32%)
factor NOT associated with outcome in patients with IVDD
–location
define rhizotomy
severance of nerve root (as long as it is not part of lumbar plexus)done to increase exposureavoided bc body wall weakness occurs
Mayhew et al 2004 JAVMA229 IVDD dogs followed out for 3.7 yearsrate of recurrence
No fenestration performed20% recurrence within 3 years of surgery
laser disc ablation as an alternative to prophylactic disc fenestration
percutaneous approachT10-L4Holmium:yttrium-aluminum-garnet (Ho:YAG) laser to ablatecomplications: pneumothorax, abscessation at percutaneous needle site, discospondylitits, worsening neuro signs
nerves involved in micturition
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
alpha adrenergic antagonists
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
Bubenik Vet Sx 2008what conclusion from method of bladder evacuation and risk of bacterial UTI
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
US assessment for adequate post void bladder size
< 30 kg patient 3 cm> 30 kg patient 4-5 cm
list congenital/developmental malformations of the TL spine
–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
