14. Spinal cord compression (including sciatica) Flashcards
The spinal cord runs between which 2 points?
Cord extends from C1 (junction with medulla) to L1/L2 (conus medullaris)
What is located below L1?
Lumbar & sacral nerve roots - grouped together to form the CAUDA EQUINA
What is the final point of the spinal cord called?
Cauda Equina
What is paraplegia?
Paralysis of BOTH LEGS ALWAYS caused by spinal cord lesion
What is hemiplagia?
Paralysis of ONE SIDE of body caused by lesion of the brain
What are the 3 tracts of the spinal cord?
- Corticospinal
- Dorsal column
- Spinothalamic
What does the corticospinal tract transmit?
Motor
What is the function of the corticospinal tract?
Descending UMN
Where does the corticospinal tract decussate?
85% decussates in the medulla, this is the lateral tract
15% decussates in the spinal cord, this is the medial tract
Remember that the corticospinal tract is motor, so impulses travel down from brain to spine.
Thus, the lateral tract is contralateral to the brain, but ipsilateral to the muscles it innervates.
What do the dorsal spinal columns transmit?
Proprioception, vibration and 2 point discrimination (fine touch)
Which spinal cord pathway has gracilis and cuneate nuclei?
What are these for?
Dorsal spinal column:
- Gracilis = medial = legs
- Cuneate = lateral = arms
What tract controls “nice sensations”?
Where does it decussate?
Dorsal columns - for touch, vibration, proprioception.
Gracile fasciculus - legs AND cuneatus fasciculus - arms.
Decussate in upper medulla.
Where do the dorsal spinal columns decussate?
Medulla
What does the spinothalamic tract transmit?
Pain and temperature
Where do the spinothalamic tracts decussate?
Spinal cord
If UMN signs are present, where does it indicate the lesions are?
Indicate that the lesion is above the anterior horn cell
I.E. in the spinal cord, brainstem and motor cortex
Describe the features of a UMN lesion.
- Increased muscle tone - spasticity
- Pyramidal Weakness:
- In legs: flexors are weaker than extensors
- In arms: extensors are weaker than flexors - Increased reflexes, they are brisk - HYPERREFLEXIA
If LMN signs are present, where does it indicate the lesions are?
Indicate that the lesion is either in the anterior horn cell or distal to the anterior horn cell
I.E. in anterior horn cell, nerve roots, plexus or peripheral nerve
Describe the features of a LMN lesion.
- Decreased muscle tone
- Muscle wasting (atrophy) ± fasciculation (spontaneous involuntary twitching)
- Weakness that corresponds to those muscles supplied by the involved cord segment, nerve root, part of plexus or peripheral nerve.
- Reduced/absent reflexes
- Hypotonia/flaccidity - limb feels soft and floppy
Define spondyloisthesis.
Slippage of vertebra over the one below.
- Nerve root comes out ABOVE the disc, therefore root affected will be the one BELOW the disc herniation
e.g. L4/L5 herniation leads to L5 nerve root compression
Define spondylosis.
Degenerative disc disease.
Define myelopathy.
- Spinal cord disease.
- UMN problem + signs r.g. spasticity, weakness, hyper-reflexia.
Caused by spinal cord compression.
Surgery is often indicated to prevent deterioration.
Define radiculopathy.
Spinal nerve root disease; LMN problem + signs e.g. decreased muscle tone, wasting, weakness and fasciculations.
Caused by spinal root compression.
Is myelopathy or radiculopathy an UMN problem?
Myelopathy is a spinal cord disease and therefore is an UMN problem.
Is myelopathy or radiculopathy a LMN problem?
Radiculopathy is a spinal nerve root disease and therefore is a LMN problem.
What is a myotome?
A myotome (greek: myo=muscle, tome = a section, volume) is defined as a group of muscles which is innervated by single spinal nerve root
Which myotome does C5 innervate?
Shoulder abduction/biceps jerk
Which myotome does C6 innervate?
Elbow flexion/supinator jerk
Which myotome does C7 innervate?
Elbow extension/triceps jerk