Spinal Cord Compression Flashcards
Main white matter tracts?
Motor - corticospinal tracts (located in the lateral white matter)
NOTE - consists of UMNs and LMNs
Sensory :
• Spinothalamic tracts (located in the anterolateral white matter)
• Dorsal columns (located in the posterior / dorsal white matter)
NOTE - consist of 1st, 2nd and 3rd order neurones
Difference between grey and white matter?
White matter - myelinated axons
Grey matter - cell bodies of neurones
Pathway of the corticospinal tract?
2 neurones:
• Upper motor neurone (UMN) - runs from the motor cortex to the anterior grey horn; decussation occurs at the level of the medulla
This means it runs IPSILATERAL to the side of the body it supplies but info is received in the contralateral motor cortex
• Lower motor neurons
Signs of an UMN lesion?
Increased tone, due to loss of inhibition; in the case of an UMN lesion, this is called spasticity
Loss of power (weakness):
• Extensors weaker than flexors in the arms
• Flexors weaker than extensors in the legs
Hyper-reflexia (brisk reflexes)
Babinski sign is present (up-going plantar response),as the UMN of the corticospinal tract is damaged, so other descending pathways dominate
Muscle wasting that is NOT MARKED
No fasciculations
Where do UMN lesions occur?
Above the anterior horn cell, i.e: spinal cord, brain stem, motor cortex
NOTE - anterior horn cells are the cell bodies of the LMNs; they are located in the anterior grey matter of the spinal cord
Features of spasticity that differentiate it from rigidity?
It is VELOCITY-DEPENDENT
Present predominantly in:
• FLEXOR muscles and forearm pronators of the ARMS
• EXTENSOR muscles of the LEGS
Normal plantar response?
Should normally cause toe flexion
Great toe will extend and other toes will fan (Babinski sign) in UMN lesions
Signs of a LMN lesion?
Decreased tone
Muscle wasting
Fasciculations
Diminished reflexes (hyporeflexia) or areflexia
Babinski sign is absent
Where do LMN lesions occur?
Either in the anterior horn cell OR distal to the anterior horn cell, i.e: anterior horn cell, root, plexus, peripheral nerve
Pathway of the spinothalamic tracts?
1st order neurone enters spinal cord and then 2nd order neurone immediately decussates at that spinal cord level
i.e: the tract runs CONTRALATERAL to the side of the body it supplies and info reaches the contralateral sensory cortex
Function of the spinothalamic tract?
Supplies, to the contralateral side of the body:
• Crude (non-discriminative touch)
• Pain
• Temperature
Pathway of the dorsal columns?
Decussation occurs at the level of the medulla, so the tract runs on the IPSILATERAL side as the side of the body it supplies
Function of the dorsal columns?
Supplies, to the ipsilateral side of the body:
• Fine (discriminative) touch
• Proprioception
• Vibration
With which tuning fork is vibration sense tested?
128Hz
Categories of spinal cord compression?
Acute VS chronic
Complete (everything is damaged) VS incomplete (some residual motor / sensory function)
Causes of acute spinal cord compression?
Trauma
Tumours (commonly metastases) can cause haemorrhage or collapse
Infection
Spontaneous haemorrhage
Causes of chronic spinal cord compression?
Spondylosis (degenerative disease)
Tumours
Rheumatoid arthritis (common cause of cervical instability)
Presentation of acute cord transection?
This is a complete lesion, i.e: all motor and sensory modalities beyond that point are affected
NOTE - sensory level can be located by checking dermatomes
Motor level can be located by checking myotomes
Initially, they have flaccid areflexic paralysis (AKA spinal shock) below the level of the injury; this is an acute, transient stage of spinal cord lesions and the classic UMN signs appear later
Signs of flaccid arreflexic paralysis?
Hypotonia; muscles become flaccid and cannot contract
Areflexia
What is Brown-Sequard syndrome?
Incomplete spinal cord injury that occurs due to cord hemisection, i.e: injury to one side of the spinal cord
This results in symptoms on the:
• Ipsilateral motor level (as the CST runs on the ipsilateral side)
• Ipsilateral dorsal column sensory level
• Spinothalamic sensory level
Symptoms of Brown-Sequard syndrome?
Ipsilateral motor level - loss of motor function on the ipsilateral side (as the lesion)
Ipsilateral dorsal column sensory level - loss of the following on the ipsilateral side:
• Fine touch
• Proprioception
• Vibration
Contralateral spinothalamic sensory level - loss of the following on the contralateral side:
• Coarse touch
• Pain
• Temperature
What is central cord syndrome?
Most common form of incomplete spinal injury;
Mainly caused by hyperflexion or extension injury to an already stenotic neck
Symptoms of central cord syndrome?
Main symptom is DISTAL UPPER LIMB WEAKNESS:
• Complete paralysis of hands
• Weakness at wrists
• Able to move elbows and shoulders
PRESERVATION OF LOWER LIMB POWER
‘Cape-like’ spinothalamic sensory loss (of coarse touch, pain and temperature in this distribution)
Functions of dorsal column are preserved
How does the somatotopic organisation of the anterior horn cells relate to the pattern of weakness in central cord syndrome?
Only the central part of the spinal cord is damaged
As the anterior horn cells corresponding to the hands are most central, they suffer complete paralysis
As the anterior horn cells corresponding to the elbows and shoulder are more lateral, function is partially preserved
As the anterior horn cells corresponding to the legs are most lateral, function is completely preserved, as this area of the spinal cord is undamaged
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