Disorders of the Thoracolumbar Spine Flashcards
How are the pelvic and thoracic limbs affected by T3-L3 spinal cord lesions?
PELVIC - proprioceptive deficits, UMN voluntary motor deficits
THORACIC - normal, Schiff-Sherrington
Other than thoracic and pelvic limb abnormalities, what are 4 other effects of T3-L3 spinal cord lesions?
- Horner’s syndrome
- cutaneous trunci deficits
- UMN bladder dysfunction
- nociceptive deficits
What are 5 steps in the pathophysiology of thoracolumbar disk degeneration?
- chondroid degeneration
- degradation of nucleus pulposus
- weakening of dorsal annulus
- calcification of nucleus pulposus
- extrusion of nucleus contents into vertebral canal
What signalment is most commonly associated with Type I disk extrusion in the thoracolumbar spine?
> 3 y/o small breeds - Dachshunds
- cervical extrusions common too
What spinal segments are most commonly affected by thoracolumbar disk extrusion in small and large dogs? What is the most common sign?
(herniation, Type I)
- SMALL DOGS = T12/T13, T13/L1
- LARGE DOGS = L1/L2, L2/L3
acute onset, rapid progression of nonambulatory paraparesis or paraplegia (pelvic limbs!)
What are the most common clinical signs of thoracolumbar disk extrusion?
- back pain, often confused with abdominal pain
- paraparesis, paraplegia - pelvic limbs!
- UMN urinary incontinence
- pain sensation affected
How are thoracolumbar disk extrusions diagnosed?
- based on signalment and clinical signs if surgery is not planned
- MRI if surgery is planned
- survey radiographs
When is medical management for thoracolumbar disk extrusion recommended?
ambulatory patients
- ambulatory status does NOT preclude surgical intervention
- non-surgical management is NOT recommended for non-ambulatory patients
What does it mean when a patient has no deep pain perception with thoracolumbar disk extrusion? What treatment is recommended?
pelvic limbs are paralyzed with no behavioral withdrawal response in the toes
there is a decreased prognosis with surgical success because the onset of lost sensation is often not known (some literature recommends surgery within 48 hr) —-> patients often do well remaining paralyzed and using a cart and urinary management
What is myelomalacia? What is prognosis like?
liquefaction of the spinal cord parenchyma, typically requiring durotomy and direct visualization for diagnosis
- focal = better prognosis
- ascension/descension = euthanasia recommended
What 3 disorders are commonly associated with constrictive myelopathy? What region is most common? Breed?
- disk protrusion
- subarachnoid diverticulum
- syrinx - fluid-filled cyst
thoracolumbar
Pugs
What is the most common cause of constrictive myelopathy in Pugs?
dysplasia (hypoplasia/aplasia) of caudal articular processes thought to be due to chronic instability and arachnoid adhesions
What surgery is performed in Pugs with constrictive myelopathy?
decompressive surgery —> poor outcomes
What post-operative care is commonly indicated for patients with thoracolumbar myelopathies?
- pain management
- bladder care
- rehabilitation, physical therapy
- GI protectants
What is thoracic vertebral kyphosis/kyphoscolosis? In what breeds is it most commonly found? What region of the spinal cord is most commonly affected?
congenitally malformed hemivertebrae (butterfly) caused by developmental errors in vertebral segmentation and ossification —> ventral aplasia
commonly an incidental finding in screw-tailed breeds (Frenchies) - 60% <1 y/o
mid to caudal thoracic, usually T6-T9
What are the 2 opinions on surgical management of kyphotic thoracic vertebral body malformations?
no need to realign due to likelihood of traumatizing the spinal cord needlessly
could decompress and stabilize for comfort
What is degenerative myelopathy? What is the etiology?
slowly progressive, non-painful, T3-L3 myelopathy resulting in loss of myelin and axons in the spinal cord
SOD I mutation analogous to ALS in humans
How are patients most commonly affected by degenerative myelopathy? What secondary finding may be associated?
typically progresses to non-ambulatory status by 6-12 months
poor patellar reflexes —> be wary of other diagnoses in Shepherds
What treatments of degenerative myelopathy have shown benefit?
- physiotherapy
- underwater therapy
- laser
What is fibrocartilaginous embolic myelopathy (FCE)? What breeds is it most common in? Which have certain predispositions?
embolization of fibrocartilage from the nucleus pulposus, causing peracute death of the spinal cord
large breeds
- Schnauzers
- Shelties
What are characteristic signs of fibrocartilaginous embolic myelopathy?
- most commonly seen during exercise
- pain at onset, usually not thereafter
- marked assymetry
What is the preferred imaging mode for fibrocartilaginous embolic myelopathy? What treatment is most important?
MRI
physical therapy —> guarded to good prognosis
What are the 4 most common extradural spinal tumors?
- osteosarcomas
- chondrosarcomas
- myeloma
- lymphoma
What are the 3 most common intradural/extramedullary spinal tumors?
- meningioma
- malignant nerve sheath tumor
- nephroblastoma
What are the 2 most common intramedullary spinal tumors?
- gliomas
- intramedullary metastasis
What is the preferred diagnostic for spinal tumors? What else can be performed?
MRI
- radiography - bony lesions
- CT
- myelography
What is treatment of spinal tumors dependent on? What supportive and definitive therapy is available?
location with respect to the spinal cord
glucocorticoids for pain relief - no NSAIDs at the same time!
surgery, radiation, chemotherapy
10 y/o MC Labrador mix presented with worsening right pelvic limb lameness. MRI shows L5 nerve sheath tumor. What considerations alter treatment?
- L5 is anatomically significant
- however, due to age, the tumor may have been there long enough for rerouting to occur
What is prognosis like for spinal cord tumors?
- meningioma = fair
- malignant nerve sheath tumor = poor
- nephroblastoma = initially fair, poor overall due to common recurrence