Week 7 - SCI and FES Flashcards
What are the tracts located in the white matter in the spinal cord?
Exterior white matter - conduction tracts (bundles of axons)
Ascending tracts - fibres that run to the higher cord of brain centres
Descending tracts - fibres that run to lower levels for motor output
what happens with a Lower Motor Neuron lesion?
Affects nerve fibres travelling from the anterior horn of the spinal cord or the motor nuclei of the cranial nerves to the relevant muscle
what happens with a Upper Motor Neuron lesion?
Occurs in the neural pathway above the anterior horn cell of the spinal cord or the motor nuclei of the cranial nerves (in the brain or the spinal cord)
what neurons are affected in most SCIs and why?
UMN lesions because the spinal cord is a part of the CNS
Where are LMN lesions seen?
when the damage is to the peripheral nerves (the cauda equina) or following an infarct to the cord.
is it possible to have both LMN and UMN spinal cord damage?
yes if there is spinal cord damage and the adjacent spinal root is involved
what is the difference between Quadriplegia/Tetraplegia and Triplegia (Important)
Quadriplegia/Tetraplegia:
- Partial or total loss of use of all 4 limbs and torso.
- Usually sensory and motor.
- Levels C1-C7.
Triplegia:
- Partial or total loss of use of 3 limbs (usually both legs and one arm; but can also involve both arms and one leg)
what is Paraplegia?
- Partial or total loss of use of lower extremities.
- Torso may be involved.
what is Monoplegia?
Partial or total loss of use of one limb (usually the arm).
what is Diplegia?
Stiffness, weakness, or lack of mobility in muscle groups on both sides of the body (eg diplegic cerebral palsy)
Where are lesions found in UMN and LMN disorders?
UMN Lesion:
- Cerebral hemispheres
- cerebellum
- brainstem
- spinal cord.
LMN Lesion:
- Anterior horn cell
- nerve roots
- peripheral nerves
- neuromuscular junction
- muscles.
How does muscle weakness present in UMN vs LMN lesions?
UMN Lesion:
- Quadriplegia
- hemiplegia
- diplegia
- paraplegia
LMN Lesion:
- Proximal weakness (myopathy)
- distal weakness (neuropathy).
How does muscle tone differ in UMN and LMN lesions?
UMN Lesion:
- Spasticity
- rigidity
LMN Lesion:
- Hypotonia (reduced muscle tone)
Are fasciculations present in UMN and LMN lesions?
UMN Lesion:
- Absent
LMN Lesion:
- Present, especially in the tongue
How are deep tendon reflexes affected in UMN vs LMN lesions?
UMN Lesion:
- Hyperreflexia (exaggerated reflexes)
LMN Lesion:
- Hyporeflexia or areflexia (reduced or absent reflexes)
Are abdominal reflexes present in UMN and LMN lesions?
UMN Lesion:
- Absent (depending on the spinal level involved)
LMN Lesion:
- Present
What type of sensory loss occurs in UMN and LMN lesions?
UMN Lesion:
- Cortical sensory loss.
LMN Lesion:
- Peripheral sensory loss
How does Electromyography (EMG) differ in UMN and LMN lesions?
UMN Lesion:
- Normal nerve conduction with decreased interference pattern and firing rate.
LMN Lesion:
- Abnormal nerve conduction
- large motor units
- fasciculations
- fibrillations.
How does muscle wasting differ in UMN and LMN lesions?
UMN Lesion: Appears later, mainly due to disuse.
LMN Lesion: Usually present with lower motor neuron damage.
what are the levels of the American Spinal Cord Association Impairment Scale (ASIA)?
ASIA A: Complete
- No motor or sensory function
ASIA B: Incomplete
- Sensory but NOT motor function is preserved below the neurological level
ASIA C: Incomplete
- Motor function is preserved below the neurological level, half of muscles grade of less than 3
ASIA D: Incomplete
- Motor function, more than half of muscles greater than or equal to 3
ASIA E: Normal
- Normal motor and sensory function
What does ASIA A L7 mean?
complete break of the spinal cord at lumbar 7 with the loss of motor and sensory below that region
what are 6 Spinal Cord Injury Syndromes?
1.Central Cord Syndrome
2.Brown-Sequard Syndrome
3.Anterior Cord Syndrome
4.Posterior Cord Syndrome
5.Conus Medullaris Syndrome
6.Cauda Equina Syndrome (Note: not considered a true SCI)
what is Central cord syndrome?
- Usually occurs in the cervical spine
- injury from a fall or an MVA
- tumours and cervical disc bulges are common
- Is the most common of the SCI syndromes
- Often exhibits bladder dysfunction and can present with varying degrees of sensory loss below the neurological level
what is Brown-Sequard Syndrome?
- Results from a hemisection of the spinal cord
Causes:
- Spinal tumor
- Spinal cord infection (e.g., tuberculosis)
- Inflammation of the spinal cord (e.g., multiple sclerosis)
- Penetrating wounds (e.g., knife stabbing, gunshot wound)
Ipsilateral (same side) losses below injury level:
- Proprioception
- Vibration
- Two-point discrimination
- Fine touch
- Possible motor function loss
Contralateral (opposite side) losses:
- Pain sensation
- Temperature
- Crude touch