What can lesions in LMN cause?
loss of reflex, loss of voluntary control, atonia, flaccid paralysis, rapid muscle atrophy
What can lesions in UMN cause?
oss of “calming effect”; loss of voluntary control; reflex intact and may be hyperactive, hypertonia, spastic paralysis.
What are the main causes of spinal cord dysfunction?
Compression
Contusion
Laceration
Ischaemia
Inflammation
From grade 1-5, what are the clinical signs for each grading?
1 - spinal pain
2 - Paresis (ambulatory)
3 - Non-ambulatory paresis
4 - Paralysis
5 - Paralysis with absence of pain perception
How could you treat spinal cord lesions?
Surgical decompression
Appropriate treatment for infection / inflammation
Physical rehabilitation
Define tetraparesis
reduced voluntary motor function in all 4 limbs
Define tetraplegia
total absence of voluntary motor function in all 4 limbs.
What clinical signs will you see in cervical spondylomyelopathy?
Progressive ataxia
Tetraparesis
Neck pain
What can cause cervical spondylomyelopathy?
Progressive spinal cor compression
Can be result of congenital stenosis and degenerative changes in the vertebral column
How would you treat cervical spondylomyelopathy?
Surgery for patients with neurological deficits (to decompress/stabilise) the cervical spine.
Medical includes treatment of pain, restriction of unmonitored activity and controlled exercise/physical therapy.
Describe intervertebral discs
Intervertebral discs are fibrocartilagenous cushions between the vertebra
Outer rim (annulus fibrosus) and inner ‘jelly like’ centre (nucleus pulposus).
Allow movement, support and act as shock absorbers
Describe acute cervical disc disease (Hansen type I)
Hansen Type I; chondroid degeneration of nucleus pulposus; either bulges into spinal canal – progressive disease
or
Dorsal extrusion through annulus fibrosus - acute spinal trauma
What breeds is acute cervical disc disease common in (Hansen type I)?
Shih tzu
Dachsunds
Pekingese
Beagles
What are the clinical signs of acute cervical disc disease (Hansen type I)?
severe neck pain; head held down, rigid neck, back arched (transfer weight to pelvic limbs)
What neurological signs may be seen in acute cervical disc disease (Hansen type I)?
tetra/hemi paresis/plegia, ataxia, proprioceptive and postural deficits.
Describe the pathogenesis of acute cervical disc disease (Hansen type I)
nucleus pulposus (gelatinous) premature aging in chondrodysplastic breeds
Hansen Type I disease
C2-C3 most commonly affected in small breeds
C6-C7 in large breeds
How would you diagnose acute cervical disc disease (Hansen type I)?
Clinical signs
Diagnostic imaging
Describe medical management of acute cervical disc disease (Hansen type I)
Pain relief and strict cage rest (4 weeks). Aim of cage rest is to allow annulus fibrosus to heal.
If neck pain ↓ gradual reintroduction to exercise
If pain persists or returns or neurological deficits are present requires surgery.
Describe surgical treatment of acute cervical disc disease (Hansen type I)
Ventral slot (to remove extruded material) with fenestration of adjacent discs (opening into annulus)
Post surgery; pain relief & confinement for 4 weeks (2 weeks cage rest; 2 weeks progressive return to exercise)
Physiotherapy
Describe acute cervical disc disease (Hansen type II)
Fibrinoid degeneration of nucleus pulposus and protrusion of annulus fibrosus (hypertrophy) into spinal canal
More common
What animals are more prone to acute cervical disc disease? (Hansen type II)
More common in older, non-chondrodystrophic dogs
What are the clinical signs of acute cervical disc disease? (Hansen type II)
chronic, slowly progressive signs. Spinal pain may or may not be evident
Neurological deficits often less severe than with type 1 disease.
Describe treatment for acute cervical disc disease (Hansen type II)
conservative in milder cases, surgery indicated when neurological deficits are more severe.
Describe acute cervical disc disease (Hansen type III)
Explosion of the nucleus pulposus from a sudden tear in the annulus typically associated with heavy exercise or trauma.
Aka High velocity low volume extrusion
Describe tretraparesis caused by atlantoaxial instability
Instability of atlas and axis junction
Congenital form – onset of signs most commonly seen in dogs less than 2 years age
Trauma
What are the signs of Atlantoaxial Instability?
neck pain (waxing and waning), ataxia, tetraparesis, postural and proprioceptive deficits
normal or increased myotactic reflexes/ muscle tone
How would you treat Atlantoaxial Instability?
Medical; for those cases with mild signs
External splint for 6 weeks – to stabilise and allow ligaments to heal
Surgical management; required if neurological deficits present
Stabilisation of atlanto-axial junction – screws, pins etc.
What are the two common causes of traumatic spinal injury?
fractures and luxations.
Describe medical and surgical management of a traumatic spinal injury
Medical management – splints / cage rest
Surgical management – spinal stabilization
Describe tetraparesis caused by Fibrocartilagenous embolism (FCE)
Signalment; Peracute onset of non-painful neurological deficits
Usually large, young non-chondroplastic breeds – commonly at lumbosacral intumescence
Also smaller breeds represented; Shetland Sheepdog, Miniature Schnauzer, Yorkshire Terrier – usually C6-T2
What is the pathogenesis of FCE?
fibrocartilagenous embolism from spinal structure – spinal blood vessel blocked– ischaemic necrosis of spinal cord grey matter.
State the clinical signs of FCE
often lateralised – hemiparesis
May get Horner’s Syndrome (sympathetic system affected) and vasodilation on the affected side (up to 10°C warmer)
What are two bacterial causes of tetraparesis?
Tetanus (Clostridium tetani)
Botulism (Clostridium botlulinum)
Describe paraparesis
Most common cause is disease of the thoracolumbar spine.
Clinical signs dependent on where cord is affected; T3-L3 or L4-S3.
What complications can occur from an acute severe spinal cord injury?
Neurogenic shock
Spinal shock
Describe neurogenic shock
Sympathetic ns dysfunction (with parasympathetic function) – decreased blood pressure, heart rate – may lead to ischaemia – kidney failure
Present in humans; rarely clinically in dogs/cats
Describe spinal shock
Flaccidity caudal to the lesion – decreased spinal reflexes
Describe paraparesis caused by degenerative myelopathy
Insidious, progressive ataxia and paresis of pelvic limbs progressing to paraplegia
Initially recognised in GSD, but other breeds as well
Average age of onset – 9 years
What are the signs of degenerative myelopathy?
early; general porprioceptive ataxia and mild spastic paresis of pelvic limbs; worn nails on pelvic limbs
most large breed dogs progress to non-ambulatory within 6 – 9 months
Late stage – LMN signs in pelvic limbs and UMN signs in thoracic limbs; eventually tetraplegia
Severe muscle atrophy
What are the treatment options for degenerative myelopathy?
non-specific. Poor prognosis. Physiotherapy and hydrotherapy may help manage the condition (maintenance of muscle strength) and associated with longer survival.
Describe paraparesis caused by Type I Hansen disc disease
Back pain, kyphosis, reluctance to walk
Paraplegia, reduction in nociceptor responses
In small breeds most commonly at T12-T13; in Large Breeds mainly L1-L2
Describe treatment for Type I Hansen Disc disease (paraparesis)
Medical management; for mild spinal pain -as per cervical lesions
Surgical management;
Spinal cord decompression
Dorsal laminectomy
Hemilaminectomy (lateral approach) + fenestration
Post surgical management as per cervical lesions
Describe monoparesis
Monoparesis / plegia?
Nerve Root Signature = pain manifested as lameness due to nerve root irritation / compression
What nerves can cause monoparesis?
Brachial plexus- network of nerves innervating the forelimb (arise from spinal nerves C6-T2).
Lumbosacral plexus- network of nerves innervating the hindlimb (arise from L4-S3 in the spinal cord).
Define neuropraxia
interruption of nerve conduction without physical disruption of the axon.
Define axonotemesis
physical interruption of the axon.
Define neurotemesis
complete severance of the nerve- most severe type of injury.
Describe foraminal stenosis
Narrowing of foramen where nerve roots exit
LMN signs localised to one or more nerve roots
Nerve root signature;
pain on manipulation or palpation of affected limb
Lameness of affected limb – may avoid weight-bearing
May be constant, intermittent or exacerbated by exercise
Describe treatment for foraminal stenosis
Medical management; NSAIDs and pain relief (but often signs return)
Surgical; dorsal laminectomy and/or foraminotomy
Describe brachial plexus avulsion
RTAs, fall from height – adduction and caudal displacement of thoracic limb
Acute onset; either
Cranial avulsion (C6-C8 nerve roots)
Caudal avulsion (C8-T2)
Complete avulsion (C6-T2)
What are the clinical signs of brachial plexus avulsion?
Cranial is rare and few clinical signs;
Atrophy of supra/infraspinatus
Loss of shoulder flexion/extension; loss of elbow flexion. Can bear weight.
Caudal and Complete more common and more severe signs;
Loss of elbow extension (triceps brachii) – no weight-bearing and drags limb with carpus knuckled.
Severe neurogenic atrophy
Caudal alone – flexor muscles work therefore tends to carry limb
Describe treatment for brachial plexus avulsion
Non-specific – physiotherapy and keep limb clean and protected
Cranial avulsions can bear weight and have a good prognosis
Complete/caudal avulsions – poorer prognosis; depends on severity of nerve damage.
May require limb amputation