Diseases of the Spine, PNS, NMJ and Muscle in the Dog and Cat Flashcards
What are the DDx for Spinal Pain?
D: Intervertebral disk disease, or Lumbosacral stenosis
A: Atlantoaxial subluxation, Chiari-like malformations, Caudal cervical malformation/ Malarticulation
M:
N: Primary vs Secondary Neoplasia of the vertebrae, nerve root or intracranial
I: Discopondylitis, Meningitis, polymyositis or polyarthritis
T: Vertebral Fracture
V:
What is Steroid-responsive meningitis-arteritis (SRMA)?
A noninfectious inflammatory disease of the meninges
Suspected to be immune-mediated in origin, with an overrepresentation in certain breeds: Bernese Mt Dog, Pointer and Beagle
(Medium to large breed dogs 8-18 months of age)
What are the clinical signs associated with Steroid-responsive meningitis-arteritis (SRMA)?
- Pain in the cervical region
- Fever
- Depression
+/- waxing and waning
and usually no neurological deficits
Meanwhile neurological deficits are common with Meningoencephalitis of unknown origin (MUO) or GME
How can Steroid-responsive meningitis-arteritis (SRMA) be diagnosed?
- CSF tap + analysis: will see marked neutrophilic pleocytosis
+/- neutrophilia on hematology
How can Steroid-responsive meningitis-arteritis (SRMA) be treated/ managed?
- Immunosuppressive doses of corticosteroids
What is syringomyelia?
What is hydromyelia?
Syringomyelia is the development of a CSF-filled cavity (syrinx) within the parenchyma of the spinal cord
Hydromyelia is the accumulation of excessive CSF within a dilated central canal
Why does syringomyelia or hydromyelia develop?
These can develop as a result of:
- Altered CSF pressures within the spinal canal
- A loss of spinal cord parenchyma
- Secondary to obstructed CSF flow caused by congenital malformations, trauma, or inflammatory/ neoplastic disorders
What is Chiari-like malformation and why might it lead to syringomyelia or hydromyelia?
Chiari-like malformation is a congenital malformation of the skull in Cavalier King Charles Spaniels
The malformation of the skull reduces the volume of the caudal fossa and displaces the cerebellum and brainstem into the foramen magnum, thus obstructing CSF movement
The CSF, which normally flows through the foramen magnum during systole becomes turbulent at the craniocervical junction, leading to syrinx formation
How can Chiari-like malformation be confirmed/ diagnosed in the CKCS?
- 95% of CKCS have some degree of CM, 50% of those will have syringomyelia, and 35% of those affected show clinical signs
- Clinical signs: cervical pain (can be intermittent), may resent having their ears, limbs, face or neck touched. Some dogs will phantom scratch (scratch at their neck without making contact with the skin). Can also see neurological deficits
- MRI: see a decreased caudal fossa due to congenital hypoplasia of the occipital bone, leading to herniation of cerebellum + compression of the craniocervical dural/ fibrous band
How can clinically affected CKCS with Chiari-like malformation be treated/ managed?
Medical:
- Analgesia: Gabapentin for neuropathic pain
- Drugs to decrease CSF production: Omeprazole, acetazolamide or prednisone
if medical management does not work, then surgical should be considered
- Dorsal laminectomy +/- durotomy
What are the DDx for Ataxia?
D: Intervertebral disk disease, degenerative myelopathy
A: Atlantoaxial subluxation, caudal cervical malformation/ malarticulation
M:
N: Primary vs secondary neoplasia
I: Discospondylitis, Meningomyelitis
T: Trauma
V:
What is Degenerative Myelopathy?
A degenerative disorder of the spinal cord white matter, characterized by widespread myelin and axon loss with no evidence of cord compression or inflammation, usually most severe in the mid to caudal thoracic spinal cord.
Cause is unknown but a mutation in the Superoxidase Dismutase 1 gene (SOD1) has been identified as a necessary condition for the development of this disease
Overrepresentation in certain breeds: GSD and Boxers (6-12 years old) and other medium and large breeds
What are the clinical signs associated with Degenerative Myelopathy in dogs?
Insidious onset of signs
- Mild proprioceptive pelvic limb ataxia and paresis leading to limb knuckling, and wearing of the dorsal nail surface, chronic cases can result in complete paresis until non-ambulatory
- Normal or increased rear limb reflexes
How can Degenerative Myelopathy be diagnosed in the dog?
Diagnosis is of exclusion:
- Clinical signs + breed and age of onset: must be differentiated from spinal cord neoplasia, spinal cord compression by articular cysts and type II disk protrusion
- Rads: will be normal
- CSF analysis: will be normal +/- slight protein increase
- Myelography or MRI: to rule out spinal cord compression or neoplasia
Definitive diagnosis: PM findings of axonal degeneration, demyelination, and astroglial proliferation in the lateral funiculus and dorsal columns of the thoracic spinal cord
How can Degenerative Myelopathy be treated/ managed in dogs?
Treatment: none
Do NOT give steroids as they can cause muscle wasting and exacerbate muscle weakness
Management:
- Vitamin E, Vitamin B complex, Vitamin C + omega-3 FAs and antioxidants may help
- Exercise + intensive targeted physiotherapy may help in slowing disease progression
What are the DDx for Tetraparesis/ tetraplegia or Hemiparesis/ hemiplegia?
D: Intervertebral disk disease, diskospondylitis
A: Atlantoaxial subluxation, caudal cervical malformation/ malarticulation, Chiari-like malformation, Myasthenia gravis
N: neoplasia can cause this if hemorrhage, ischemia or fracture occurs as a result
I: viral, bacterial, fungal, parasitic infection, meningomyelitis, tick paralysis, acute polyradiculoneuritis
T: Trauma, Botulism, snake envenomation, aminoglycoside intoxication
V: hemorrhage, fibrocartilagenous embolism
What is the definition of Tetraparesis?
Weakness in all 4 limbs with some voluntary movement maintained
Mild: weak but ambulatory
Moderate: weak, non-ambulatory + sternal recumbency
Severe: weak, non-ambulatory + lateral recumbency
What is the definition of Tetraplegia?
Loss of voluntary movements in all 4 limbs
What is a Fibrocartilaginous Embolism and why does it occur?
A fibrocartilage piece breaks off, likely from the nucleus pulposus of a degenerating IVD and becomes trapped in a very small artery or vein that supplies the spinal cord, parenchyma and leptomeninges, leading to infarction
The reason for this to occur is unknown, but there is a genetic predisposition for young large breeds and Mini Schnauzers
What are the clinical features associated with a Fibrocartilagenous Embolism?
- Acute onset of neurological signs
- 50% of cases will have clinical signs after a minor trauma or during exertion
- Deficits will depend on the region of the spinal cord affected and the severity of the cord involvement
- Neurological dysfunction may be mild or severe, usually the thoracolumbar or lumbosacral are affected, with only about 10% of cases having cervical spinal signs
- Common for dogs to be painful at first and then present to the vet NON-painful (even with manipulation of the spine) and show asymmetrical signs
How can a Fibrocartilagenous Emboli be diagnosed?
Diagnosis of exclusion
Suspicion is based on:
- Signalment, history, recognition of peracute, nonprogressive, nonpainful spinal cord dysfunction
- Rads: will be normal, but help rule out diskospondylitis, fractures, lytic vertebral neoplasia and IVDD
- CSF analysis: will be normal, +/- increased protein
- Myelography or Spinal CT: rule out compressive lesions of the spinal cord due to fractures, disk extrusion and neoplasia
If a Fibrocartilagenous Emboli is diagnosed or suspected, what is the treatment/ management?
- Nonsupportive measures, nursing care and physiotherapy
- Cage rest is NOT required, in fact early intervention with physiotherapy may help speed recovery
Note: most clinical improvements take place in the first 7-10 days, but it can take 6-8 weeks for complete return of function
If no improvement is seen in the first 21 days, then it is unlikely the animal will improve
What is Acute Canine Polyradiculoneuritis (Coonhound paralysis)?
The only acute-onset polyneuropathy commonly diagnosed in dogs
- Clinically and histologically similar to the human Guillain Barre Syndrome: an autoimmune allergic neuritis thought to be caused by exposure to a triggering antigen
- This triggering antigen is unknown and could be anything