Lecture: Myelopathies Flashcards
Number of Vertebrae
- 7 cervical
- 13 thoracic
- 7 lumbar
- 3 sacral
Spinal Cord Segments
- 8 cervical
- 13 thoracic
- 7 lumbar
- 3 sacral
- 5 caudal
Anatomy
Dorsal funiculus (DF)
Ascending tracts for proprioception and nociception
Anatomy
Lateral funiculus
Upper motor nuron tracts facilitory to limb flexors and inhibitory to extensors.
Some ascending sensory tracts.
Anatomy
Ventral funiculus
Upper motor neuron tracts facilitory to extensors.
Inhibitory to flexors.
Upper Motor Neurons
- Originate in brain and control motor activity
- Stimulate or inhibit neurons that innevate muscles
UMN signs when lesions affect descending motor pathways
- Paresis, paralysis, postural reaction deficits, ataxia
- Hypertonus, spasticity (lack of inhibition)
- Hyperreflexia
Lower Motor Neurons
Directly innervate the muscles
LMN signs when lesions affect ventral horn of spinal cord
- Flaccid paresis/paralysis
- Hyporeflexia
- Neurogenic muscle atrophy (rapid)
Important segments
Horner’s syndrome
- Sympathetic fibers at level of T1-T3
Important segments
Phrenic nerve
- C5-C7
Important Segments
Cutaneous trunci (Panniculus)
Lateral thoracic nerve: C8-T1
Lower motor neuron areas of clinical importance
- Cervical intumescence (C6-T2)
- Lumbosacral Intumescence (L4-S3)
Clinical Signs of Spinal Cord Disease
- Paresis/plegia
- Proprioceptive deficits (ipsilateral)
- Proprioceptive ataxia
- Loss of spinal refexes depending on location
- Abnormal panniculus depending on location
- Muscle atrophy
- +/- spinal pain
- Micturation abnormalities
- Respirator difficulty in severe lesions
Dz affectly spinal cord only won’t cause
- Change in mentation/attitude
- Cranial nerve deficits
- Seizures
- Vestibular signs
Specific DX work up for Spinal cord disease
- +/- spinal rads
- Advanced imaging (Myelogram, MRI, CT)
- +/- CSF analysis
- Infectious dz testing
- Electrodiagnostics (EMG, nerve conduction)
Degenerative neuropathies
- IVDD
- Degenerative Myelopathy
- Cervical Spondylomyelopathy (CSM)
IVDD Types
- Hansen Type 1: Nucleus propulsion extrusion
- Chondrodystrophic breeds
- Hansen Type 2: Annulus fibrosis protrusion
- Non-chondrodystrophic breeds
- Hansen Type 3: Traumatic disc
IVDD imaging
MRI
CT
- MRI: best way to assess spinal cord
- CT adequate for visualizing extruded mineralized disc material
- may need myelogram
Degenerative Myelopathy
- Slowly progressive (6-12 months)
- typically starts after 5 years of age
- Begins as T3-L3 disease
- GSD posterchild
Degenerative Myelopathy
CS
- Proprioceptive ataxia and paraparesis
- Proprioceptive deficits in pelvic limbs
- Urinary/fecal incontinence in late stages
- Can affect thoracic limbs, animal often euthanized before this
DM
DX
- RULE OUT DX
- MRI rules out compressive dz
- Electrodiagnosis may show denervation
- SOD-1 gene mutation (Blood test) ONLY SUPPORTIVE
DM
TX
- None
- Physical therapy may prolong function
Cervical Spondylomyelopathy (CSM)
WOBBLERS
- Disc-Associated
- disc protrusion compresses spinal cord
- Dobermans, Weimeraner
- Osseous-Associated
- Vertebral malformation/malarticulation, ligamentous hypertropy
- Large and giant breed dogs, horses
*two engine gate
*medical vs surgical management
Anomalous myelopathies
- Atlanto-axial instability
- Vertebral Malformations
- Syringomyelia
Atlanto-axial instability
- odontoid (dens) hypoplasia/aplasia
- abnormal ligamentous support of dens
- young, toy-breed dogs
- sx stabilization usually required
Vertebral malformations
- FRENCH BULLDOGS, scretail
- hemi, butterfly, wedge, block vertebrae
- +/- clinical signs
- often incidental findings
Syringomyelia
About
- Fluid dilatation within the spinal cord outside the central canal.
- May or may not communication with central canal
- Often secondary to Caudal Occipital Malformation syndrome (COMS)
- Cavalier King Charles
- Mechanism unknown
Syringomyelia
CS
TX
- CS:
- cervical myelopathy
- phantom scratching at neck/ears
- pain
- TX
- reducing CSF production
- Pain management
Neoplasia
Spinal cord tumors
- Meningioma
- Glioma
- Lymphoma
- Nerve sheath tumors
Neoplasia
vertebral tumors
- osteosarcoma
- chondrosarcoma
- fibrosarcoma
- myeloma
Neoplasia
CS
DX
TX
Prognosis
- CS
- variable
- DX
- difficult (dangerous to sample)
- TX options
- palliative care
- surgical debulking
- radiation therapy
- Prognosis: typically guarded
Inflammatory
Non-infectious myelitis/meningomyelitis
- Probs auto-immune
- TX: immuno-suppressive medications
- Young to middle aged terriers and small breed dogs
Inflammatory
Steroid responsive Meningitis/Arteritis
- Common aseptic inflammatory disease
- SEVERE cervical pain
- Neutrophilic pleocytosis is hallmark
- +/- Leukocytosis & fever
- young (6-18mo) boxers, beagles, large/giant breeds
Infectious myelopathies
- Diskospondylitis
- Infectious myelitis/meningomyelitis
Diskospondylitis
About
DX
TX
Prognosis
- Infection of intervertebral disk and adjacent vertebral endplates
- Staph, Strep, E. Coli, Brucella
- presumptive dx with plain film rads
- tx: cephalosporins, sulfas
- long-term tx
- good prognosis
Infectious myelitis/meningomyelitis
- Very sick, painful patient, rapidly progressive
- Organisms
- bacteria rare
- hematogenous spread via innoculating trauma
- Viral
- distemper, coronavirus (FIP)
- Fungal
- cryptococcus
- Protozoa
- neospora, toxoplasma
- Rickettsiae (rare)
- Ehrlichia, RMSF
- bacteria rare
Trauma myelopathy
- Vertebral fractures
- Brachial plexus avulsion
- Penetrating wounds
Toxin myelopathy
- Tetanospasmin toxin from Clostridium tetani
- acts at level of spinal cord
- inhibits release of GABA by Renshaw cells
- causes skeletal muscle rigidity
Vascular myelopathy
- Fibrocartilagenous Embolic Myelopathy (FCEM)
- embolism of small piece of cartilage into vessel supplying spinal cord
- Mechanism unknown
- typically large/giant breed dogs, also mini schnauzers
- acute onset of signs, not typically progressive
- spinal infarct may be visualized on MRI
- Not surgical
- variable recovery rate
