Lecture: Myelopathies Flashcards
1
Q
Number of Vertebrae
A
- 7 cervical
- 13 thoracic
- 7 lumbar
- 3 sacral
2
Q
Spinal Cord Segments
A
- 8 cervical
- 13 thoracic
- 7 lumbar
- 3 sacral
- 5 caudal
3
Q
Anatomy
Dorsal funiculus (DF)
A
Ascending tracts for proprioception and nociception
4
Q
Anatomy
Lateral funiculus
A
Upper motor nuron tracts facilitory to limb flexors and inhibitory to extensors.
Some ascending sensory tracts.
5
Q
Anatomy
Ventral funiculus
A
Upper motor neuron tracts facilitory to extensors.
Inhibitory to flexors.
6
Q
Upper Motor Neurons
A
- Originate in brain and control motor activity
- Stimulate or inhibit neurons that innevate muscles
7
Q
UMN signs when lesions affect descending motor pathways
A
- Paresis, paralysis, postural reaction deficits, ataxia
- Hypertonus, spasticity (lack of inhibition)
- Hyperreflexia
8
Q
Lower Motor Neurons
A
Directly innervate the muscles
9
Q
LMN signs when lesions affect ventral horn of spinal cord
A
- Flaccid paresis/paralysis
- Hyporeflexia
- Neurogenic muscle atrophy (rapid)
10
Q
Important segments
Horner’s syndrome
A
- Sympathetic fibers at level of T1-T3
11
Q
Important segments
Phrenic nerve
A
- C5-C7
12
Q
Important Segments
Cutaneous trunci (Panniculus)
A
Lateral thoracic nerve: C8-T1
13
Q
Lower motor neuron areas of clinical importance
A
- Cervical intumescence (C6-T2)
- Lumbosacral Intumescence (L4-S3)
14
Q
Clinical Signs of Spinal Cord Disease
A
- 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
15
Q
Dz affectly spinal cord only won’t cause
A
- Change in mentation/attitude
- Cranial nerve deficits
- Seizures
- Vestibular signs
16
Q
Specific DX work up for Spinal cord disease
A
- +/- spinal rads
- Advanced imaging (Myelogram, MRI, CT)
- +/- CSF analysis
- Infectious dz testing
- Electrodiagnostics (EMG, nerve conduction)
17
Q
Degenerative neuropathies
A
- IVDD
- Degenerative Myelopathy
- Cervical Spondylomyelopathy (CSM)
18
Q
IVDD Types
A
- Hansen Type 1: Nucleus propulsion extrusion
- Chondrodystrophic breeds
- Hansen Type 2: Annulus fibrosis protrusion
- Non-chondrodystrophic breeds
- Hansen Type 3: Traumatic disc
19
Q
IVDD imaging
MRI
CT
A
- MRI: best way to assess spinal cord
- CT adequate for visualizing extruded mineralized disc material
- may need myelogram
20
Q
Degenerative Myelopathy
A
- Slowly progressive (6-12 months)
- typically starts after 5 years of age
- Begins as T3-L3 disease
- GSD posterchild
21
Q
Degenerative Myelopathy
CS
A
- Proprioceptive ataxia and paraparesis
- Proprioceptive deficits in pelvic limbs
- Urinary/fecal incontinence in late stages
- Can affect thoracic limbs, animal often euthanized before this
22
Q
DM
DX
A
- RULE OUT DX
- MRI rules out compressive dz
- Electrodiagnosis may show denervation
- SOD-1 gene mutation (Blood test) ONLY SUPPORTIVE
23
Q
DM
TX
A
- None
- Physical therapy may prolong function
24
Q
Cervical Spondylomyelopathy (CSM)
WOBBLERS
A
- 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
25
Anomalous myelopathies
1. Atlanto-axial instability
2. Vertebral Malformations
3. Syringomyelia
26
Atlanto-axial instability
* odontoid (dens) hypoplasia/aplasia
* abnormal ligamentous support of dens
* young, toy-breed dogs
* sx stabilization usually required
27
Vertebral malformations
* FRENCH BULLDOGS, scretail
* hemi, butterfly, wedge, block vertebrae
* +/- clinical signs
* often incidental findings
28
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
29
Syringomyelia
CS
TX
* CS:
* cervical myelopathy
* phantom scratching at neck/ears
* pain
* TX
* reducing CSF production
* Pain management
30
Neoplasia
Spinal cord tumors
* Meningioma
* Glioma
* Lymphoma
* Nerve sheath tumors
31
Neoplasia
vertebral tumors
* osteosarcoma
* chondrosarcoma
* fibrosarcoma
* myeloma
32
Neoplasia
CS
DX
TX
Prognosis
* CS
* variable
* DX
* difficult (dangerous to sample)
* TX options
* palliative care
* surgical debulking
* radiation therapy
* Prognosis: typically guarded
33
Inflammatory
Non-infectious myelitis/meningomyelitis
* Probs auto-immune
* TX: immuno-suppressive medications
* Young to middle aged terriers and small breed dogs
34
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
35
Infectious myelopathies
* Diskospondylitis
* Infectious myelitis/meningomyelitis
36
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
37
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
38
Trauma myelopathy
* Vertebral fractures
* Brachial plexus avulsion
* Penetrating wounds
39
Toxin myelopathy
* Tetanospasmin toxin from Clostridium tetani
* acts at level of spinal cord
* inhibits release of GABA by Renshaw cells
* causes skeletal muscle rigidity
40
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
