SA myelopathies Flashcards
Describe Schiff-Sherrington phenomena
Acute, severe lesion T3-L3; in lateral recumbency, px is flaccid in PLs and increased tone in TLs. When standing, px can use TLs fairly normal.
Where in the spinal cord is shock typically observed? What signs occur?
T3-L3 myelopathy; FLACCID paralysis in limbs caudal to lesion
What does each type function in?
Large, myelinated fibers:
Intermediately sized, myelinated fibers:
Small, central, un-myelinated fibers:
Large, myelinated fibers = proprioception (majority)
Intermediately sized, myelinated fibers = motor (middle)
Small, central, un-myelinated axons = nociception info (least)
Where in the body are the most common sources of pain / neurological deficits (5)?
Discs
Meninges
Muscles
Periosteum
Nerve Roots
What are examples of primary spinal cord injuries that cause compression, contusion, and increase spinal cord tissue pressure?
What are examples of secondary spinal cord injuries that further provoke cellular dysfunction and necrosis in tissues where primary injury has occurred?
Primary
- disc herniation; vertebral luxation; vascular injury (hemorrhage)
Secondary
- ischemia, neuroinflammation, excitotoxicity, edema
What breeds are most susceptible to IVDE (Type I) vs IVDP (Type II)?
IVDE = Chondrodystrophic dogs (short-legged dogs)
IVDP = Older, large-breed, non-chondrodystrophic dogs
Where is the genetic mutation of breeds most susceptible to IVDE?
chromosome 12 (CFA-12) = short legs + early chondroid metaplasia
beagles, frenchies, cocker spaniels; dachshunds, corgi, basset, pekinese
Describe pathophysiology of IVDE
Typically in the thoracolumbar region (T3-L3):
nucleus pulposus herniates dorsally –> tears through annulus fibrosis –> nucleus pulposus then abnormally sits in vertebral canal –> spinal cord becomes compressed
How is IVDE most commonly diagnosed? What method is not used for a definitive dx?
MRI or CT
Rads and CSF (b/c not very specific) not used for definitive dx
What is Extensive Epidural Hemorrhage Subtype?
When nucleus pulposus herniates dorsally, it tears the blood vessels running in the epidural space –> causes secondary hemorrhage
What is seen on images of IVDE?
mineralized disc material in the vertebral canal
When is it appropriate for the IVDE pt to be medically managed as a tx plan?
When pt is ambulatory, non-ambulatory with good motor function, responds well to tx
Stella: DX, TX, PROGNOSIS + RISKS
INTERVERTEBRAL DISC EXTRUSION (IVDE)
This specific case: Medical Management (suggest sx b/c non-ambulatory, but ō declined)
- Strict, prolonged (4-6 weeks) rest (to allow tear in annulus to heal)
- Analgesics (NSAIDs)
Prognosis:
- can do very well, but relapse is common. Pt MAY decline.
Risk = progressive myelomalacia developing
Barney’s dx, tx plan and prognosis?
Dx = IVDE
Tx = Surgical Management
- MRI or CT + surgery
Prognosis
- good-to-excellent (depending on grade)
- lower prognosis if pt is paraplegic and deep pain is negative
Risk = progressive myelomalacia developing (~10%)
Ascending-Descending Myelomalacia (Progressive Myelomalacia)
- Pathogenesis
- Risk Factors
- Clinical Signs
What is the prognosis / tx?
- Severe progressive spinal cord disease, 2º to injury (IVDE, Type 1 / Hansen’s -> CHONDRODYSTROPHIC dogs!)
Occurs within first 48-72 hrs post injury (jumping, landing, etc.)
. - RFs: IVDE, lumbar injury
- Pain, loss of abdominal tone, cranial progression of panniculus reflex, loss of PL reflexes and tone (as the disease progresses), eventually loss of TL function.
- Tx = euthanasia
What is IVDP? What is the tx / prognosis?
Chronic progression; Protrusion of annulus fibrosis into vertebral canal; “cobble stone street”
Tx = medical mgmt. or sx; prognosis depends on grade of severity
What are the non-degenerative IVDD?
Acute Non-Compressive Nucleus Pulpous Extrusion (ANNPE), Hydrated Nucleus Pulpous Extrusion (HNPE)
ANNPE
- etiology
- clinical signs
-tx
- Etiology: secondary to excessive force placed onto disc (vigorous exercise, trauma) -> tear in annulus fibrosis ->small fragment of nucleus pulposus herniates out and causes contusion (bruising) of SC -> peracute signs of spinal cord injury
- Clinical signs: sudden pain during activity, dog may vocalize (pain only lasts minutes-hours); asymmetric lameness, NO progression of signs after 24-48 hrs
-Tx = analgesics, nursing care
Hydrated Nucleus Pulposus Extrusion (HNPE)
- pathogenesis
- signalement
- clinical signs
- lesion on MRI
-tx
Etiology: secondary to excessive force placed onto disc (vigorous exercise, trauma) -> tear in annulus fibrosis -> part of nucleus pulposus herniates out and causes contusion (bruising) and compression of SC -> peracute signs of spinal cord injury, USUALLY CERVICAL MYELOPATHY
- Clinical signs: sudden pain during activity, dog may vocalize (pain only lasts minutes-hours); asymmetric lameness, NO progression of signs after 24-48 hrs
- any age, cat/dog
- MRI: lesion looks like a soaring bird!
-Tx = analgesics, nursing care
Fibrocartilaginous Embolism (FCE) (Ischemic Myelopathy)?
- Signalement
- Pathogenesis
- Clinical Signs
- Tx
- Mini Schnauzers predisposed; any age, Large-breed dogs
- Piece of disc (fibrocartilage) embolizes SC vasculature -> blocks blood supply -> neuro signs
- After running or playing; true pathogen. unknown
- Peracute weakness, non-progressive after 24 hours. Non-painful spine, asymmetrical (one limb more affected)
- Tx similar to ANNPE (analgesics, nursing care)
Pathophysiology of Fibrocartilaginous Embolism (FCE) (Ischemic Myelopathy)?
Piece of fibrocartilaginous (disc) embolizes the spinal cord vasculature.