Myelopathies Flashcards
What 2 vessels are the blood supply to the spinal cord?
- Dorsolateral arteries and ventral spinal arteries
- connected by an anastomosing network with an arterial ring at each intervertebral foramen
What vessel is responsible for venous return from the spinal cord?
The ventral vertebral venous plexus
What is located in the dorsal funiculus of the SC?
Ascending tracts for proprioception and nociception
What is located in the lateral funiculus of the SC?
UMN tracts facilitory to limb flexors and inhibitory to extensor; some ascending sensory tracts
What is located in the ventral funiculus of the SC?
UMN tracts facilitory to extensors and inhibitory to flexors
What is an upper motor neuron?
- Originate in the brain and control motor activity
- stimulate or inhibit the neurons that innervate the mm
What are UMN signs seen with lesions affecting the descending motor pathways?
Paresis, paralysis, postural reaction deficits, ataxia, hypertonus, spasticity (release of inhibition), hyperreflexia
What are lower motor neurons?
Those that directly innervate the muscles
What are LMN signs and when would you seen them?
- flaccid paresis/paralysis, hyporeflexia, neurogenic mm atrophy (rapid)
- Seen with lesions affecting the ventral horn of the SC
What are some important spinal segments to remember?
- Symp fibers @ level of T1-3: Horner’s
- Phrenic n: C5-7
- Lateral thoracic nerve: C8-T1 - cutaneous trunci
- Lower motor neuron areas of clinical importance:
- Cervical intumescence (C6-T2)
- Lumbosacral intumescence (L4-S3)
What are clinical signs of spinal cord disease?
- Paresis (weakness) or plegia (complete paralysis) - mono, para, tetra, hemi
- Proprioceptive deficits (ipsilateral)
- Proprioceptive ataxia
- Loss of spinal reflexes depending on location
- Abnormal panniculus
- Muscle atrophy
- Spinal pain- not in all cases
- Micturition abnormalities
- Resp difficulty (severe cervical lesions - phrenic n.)
Disease affecting only the spinal cord will NOT cause _____
- Change in mentation/attitude
- cranial nerve deficit
- seizures
- vestibular signs
What is your diagnostic work-up for SC disease?
- Obtaining thorough hx and neuro exam
- MDB, imaging, +/- spinal radiograph
- advanced imaging, +/- CSF analysis
- infectious dz testing
- electrodiagnostics
What does the DAMNITV scheme stand for?
Degenerative
Anomalous
Metabolic
Neoplastic/Nutritional
Idiopathic/Inflammatory/Infectious
Traumatic/Toxic
Vascular
What are your differentials for an immature/juvenile patient?
Trauma
Congenital malformation
Infectious
Degenerative
What are your differentials for an mature patient?
IVDD
inflammatory
FCE/Vascular
Neoplasia
What are your differentials for an geriatric patient?
IVDD
Neoplasia
Degenerative
What are your differentials for an chondodystrophoid patient?
IVDD
What is your differential diagnosis for an acute, non-progressive course of disease?
Vascular
trauma
IVDD
What is your differential diagnosis for an acute, progressive course of disease?
Trauma
IVDD
Neoplasia
Inflammatory
Infectious
What is your differential diagnosis for an chronic, progressive course of disease?
Neoplasia
degenerative
IVDD
inflammatory
infectious
What are examples of canine spinal diseases that fit in the DAMNITV scheme?
Degenerative: DM, IVDD/ANNPE
Anomoulous: Atlanto-axial instability, congenital vetebral malformations, COMs
Neoplasia: primary or metastatic
Immune/Inflammatory (GME)
Traumatic: Hemorrhage, Fracture, Luxation
Vascular: FCE, True vascular events
What are examples of feline spinal diseases that fit the DAMNITV scheme?
Cervical ventroflexion - no nuchal ligament!
D: IVDD
Neoplasia: LSA, meningioma
Immune mediated/inflammatory/Infectious: Toxo, Crypto
Trauma: Traction injury (tail pull), fracture/luxation
Vascular: hemorrhagic/ischemic infarctions
What spinal diseases do you see with equines?
- Cervical spondylomyelopathy - “wobblers”
- Infectious causes - EPM, EEE, WEE, VEE, EHV
- Trauma
What myelopathies do pigs get?
IVDD, FCE, trauma
What is the difference between the various types of IVDD?
Hansen 1: Chondrodystrophic breeds, nucleus propulsus extrusion
Hansen 2: non-chondrodystrophic breeds, annulus fibrosis protrusion
Type 3: high velocity/low volume (traumatic disc)
How do you diagnose IVDD?
Imaging:
- MRI - best way to assess the spinal cord
- CT - adequate for visualizing extruded mineralized disc material
- Myelogram
What is the treatment for IVDD?
If minimally affected, okay to try STRICT CRATE REST and medical management, surgical intervention
What is myelomalacia and how is it diagnosed and treated?
Ascending and descending hemorrhagic necrosis of the SC; only occurs in animal that is plegic with NO deep pain
- CS: ascending panniculus, loss of PL reflexes, anal tone, TL paresis, loss of ventilatory function
- Dx: No antemortem confirmatory test, imaging findings are supportive
- NO treatment > Euthanasia
When should you proceed to surgery on a myelopathy?
Treatment failure of mildly affected dogs
- progression in 24-48hrs, progression or lack of response in 1-2 weeks of medical management
- relapse when comes off meds
- Cervical pain w/ ANY deficits
- Recurrent pain, mult episodes
- LMN deficits
- Non-ambulatory status
T or F: you should wait until pain perception is lost with paraplegia to perform surgery on that patient
False; NO reason to wait! Much greater prognosis for return to function with TL IVDD if pain perception is still present
Describe feline IVDD
Extremely rare!; lumbar (L4-5) most common, mineralized discs on radiographs, very good prognosis with surgery
Describe degenerative myelopathy
- Slowly progressive disease (6-12mo)
- begins as a T3-L3 dz
- typically starts after the age of 5
- affects GSD most commonly, also Boxers and Corgis
What are clinical signs of degenerative myelopathy?
- Proprioceptive ataxia and paraparesis
- Proprioceptive deficits in pelvic limbs
- Urinary/fecal incontinence in later stages
- Can ultimately affect TLs, however typically animal is euthanized before this occurs
How do you diagnose and treat degenerative myelopathy?
- No definitive single dx test!
- MRI typically normal
- electrodiagnostics may show denervation
- SOD-1 gene mutation (blood test) - NOT DIAGNOSTIC, just supportive
Tx: nothing definitive, physical therapy can prolong functional time a bit
Describe cervical spondylomyelopathy (CSM) or “wobblers”
- Disc-associated
- protrusion causing cord compression, may have dynamic component
- In Dobies, Weimeraners
- Osseous-associated: vert malformation/malarticulation, ligamentous hypertrophy
- large/giant breed dogs most commonly affected
- Two-engine gait
What is cervical spondylomyelopathy like in horses?
Actually discovered in horses first
- Vertebral malformation - narrow spinal canal (thoroughbreds)
- Ataxia, tetraparesis, proprioceptive deficits
Describe atlanto-axial instability
Typically due to odontoid (dens) hypoplasia/aplasia, abnormal ligamentous support of the dens may also contribute
- typically young, toy-breed dogs, surgical stabilization usually required
Describe vertebral malformations and what species they are commonly found in
- Hemi vert, butterfly, wedge vert, block vert
- Presenting complaint - progressive ataxia, paresis, often non-painful
- Often animals are asymptomatic and these are incidental findings, but can be severe enough to cause clinical signs
- Common in Frenchies, pugs, English bulldogs, Bostons (breeding for “screw tail)
What does medical management entail for congenital spinal malformations? Surgical?
Med: Strict rest, Pred, pain control PRN
Sx: decompressive sx w/ stabilization, poor prognosis
What is the pathology of congenital spinal malformations?
Compression or stenosis of the canal, microinstability due to forces applied to abnormally (wedge) shaped vertebrae
What is the novel surgical approach for congenital spinal malformations?
- In-situ biological fusion
- “strip” or irritate the periosteum and apply bone graft
- do NOT open the canal/use implants
- good prognosis, the younger the better > regain ambulatory ability
What is syringomyelia?
Fluid dilatation within the spinal cord outside the central canal that may or may not communicate with the central canal
- often secondary to caudal occipital malformation syndrome (COMS) > Cavies over-represented
What are the clinical signs and treatments for syringomyelia?
CS: phantom scratching, pain, lameness
Tx: Gabapentin, Omeprazole, NSAID vs. Pred, Surgery (foramen magnum decompression)
What types of tumor can affect the spinal cord?
Meningiomas, gliomas, lymphomas, nerve sheath tumors; may also be vertebral - osteosarcoma, chondrosarcoma, fibrosarcoma, myeloma
What is the growth pattern of a meningioma?
Intra-mural, extra-medullary
What is the growth pattern of a primary glioma?
Intra-medullary
How do you diagnose and treat spinal neoplasia?
- Definitive diagnosis often difficult due to danger in obtaining samples
- Treatment options include palliative care, surgical debulking (all but intramedullary), and radiation therapy
- Guarded to poor prognosis for all tumor types
What types of spinal neoplasia do felines get?
- Spinal cord tumors: LSA (thoracic and LS), glial (cervical), and fibrosarcoma (thoracic)
- Vertebral column neoplasia (OSA)
- Meninges neoplasia
- Non-vertebral extramural neoplasia - plasma cell tumors
Describe steroid-responsive meningitis/arthritis (SRMA)
A common aseptic inflammatory dz
- Fibrinoid necrosis of vascular arterioles, commonly seen in young (6-18mo) Boxers, Beagles
- SEVERE cervical pain
- neutrophilic pleocytosis is hallmark
- +/- leukocytosis and fever
- Easy to treat! - steroids for 4-6 mo
Describe non-infectious myelitis/meningomyelitis
Suspect auto-immune basis, require immune-suppressive medications; young to middle aged terriers and small breed dogs (Yorkies, Poms, Pugs)
Describe diskospondylitis
Infection of the IVD and adjacent vert endplates
- Staph, strep, E. Coil, brucella
- Can get a presumptive diagnosis w/ plain film rads
- Tx w/ cephalosporins, sulfas
- Good prognosis
- LONG term tx
Describe infectious myelitis/meninomyelitis and most common causes
Typically very sick, painful patient
- rapidly progressive
- Bacterial- rare!
- Viral (distempter, coronavirus- FIP)
- Fungal (cryptococcus)
- Protozoa (Neospora, Toxo)
- Rickettsial (Ehrlichia, RMSF) - rare
What are differentials for feline spinal infections?
FIP <2 YO
- Bacterial myelitis
- Crypto
- Toxo
- Idiopathic
- Inflammatory
What is your prognosis for any spinal injury contingent on?
Your findings in a thorough neurological exam
What are common sources of spinal trauma?
Vert fractures, brachial plexus avulsion, penetrating wounds
What type of toxin gives you spinal cord disease?
Tetanospasmin toxin from Clostridium tetani > inhibits release of GABA by Renshaw cells (inhibitory interneurons of spinal cords)
Describe fibrocartilagenous emboli myelopathy (FCEM)
- Embolism of small piece of cartilage (likely from an IVD) into a vessel supplying the spinal cord
- MOA not known
- typically large/giant breed dogs, but Mini Schnauzers also commonly affected, young to middle age
What are the clinical signs, diagnostics, and treatment for FCEM?
- Acute onset of signs (ie paralysis)
- typically NOT progressive, usually not painful at presentation
- Spinal infarct may be visualized on MRI
- FECM is NOT a surgical dz! - no compression, recovery is variable
What do you do when you have a down cat?
- PL: check for pulses, then check for Doppler flow, then get paired NOVAs
- MDB, BP, met check thorax +/- AUS
- Prove it’s not a saddle thrombus before you send to neuro!