Spinal Cord Disorders

Question 1

When are LMN signs seen?

Answer 1

They are found in a limb if some of its muscles are innervated by anterior horn cells (lower motor neurons) are affected at the level of the spinal cord lesion.

Question 2

When are UMN signs seen?

Answer 2

They are found in a limb if a more rostral spinal cord lesion affects the corticospinal tract (upper motor neurons) descending to the anterior horn cells which innervate the muscles in that limb.

Question 3

Weakness and Atrophy in UMN Lesion

Answer 3

More diffuse, severe weakness with relatively mild atrophy

Question 4

Weakness and Atrophy in LMN Lesion

Answer 4

More focal, milder weakness with severe atrophy

Question 5

Are fasciculations seen in UMN, or LMN lesions?

Answer 5

LMN lesions

Question 6

What happens to the tonality in UMN lesions?

Answer 6

Increased - spasticity

Question 7

What happens to the tonality in LMN lesions?

Answer 7

Decreased

Question 8

What lesions increase reflexes?

Answer 8

UMN lesions

Question 9

What lesions may have clonus?

Answer 9

UMN lesions

Question 10

What lesions may have a Babinski sign?

Answer 10

UMN lesions

Question 11

What can cause radicular pain?

Answer 11

• Dorsal Root Inflammation

- Compression

Question 12

What side is there a pain and temperature deficit with a lesion in the STT?

Answer 12

Contralateral Side

Question 13

What side are position sense and vibration deficits seen on with a lesion in the DCP?

Answer 13

Ispsilateral Side

Question 14

What does sacral sparing indicate about a lesion?

Answer 14

It is intramedullary

Question 15

What does sensory loss to a particular level or in the sacral area indicate about a lesion?

Answer 15

It is extramedullary

Question 16

Transverse Myelopathy

Answer 16

A complete or nearly complete lesion encompassing the cross-sectional extent or breadth of the spinal cord at one, or a few adjacent, levels.

Question 17

What is spinal shock?

Answer 17

The expected upper motor neuron signs only gradually emerge weeks to even months later after acute trauma.

Question 18

Brown-Sequard Syndrome

Answer 18

A lesion affecting approximately the left or right half of the spinal cord cross- section at one level

Question 19

What are the signs of a Brown-Sequard lesion?

Answer 19

Involvement of the spinothalamic tract produces a contralateral deficit to pain and temperature sensation, since spinothalamic sensory fibers decussate within the spinal cord, and then continue their ascending pathway. Involvement of the dorsal or posterior columns produces an ipsilateral deficit of vibration and position sense, since these sensory fibers ascend up the same side of the spinal cord, only decussating later in the medulla.

Question 20

Syringomyelia

Answer 20

Syringomyelia refers to a spinal cord lesion from a syrinx, or cavity, within or near the center of the spinal cord. It is thus an intramedullary lesion, arising from within the spinal cord itself, and primarily affects the gray matter there.

Question 21

Intra/Extramedullary

Answer 21

Within or outside of the spinal cord

Question 22

What are the sensory deficits seen in syringomyelia?

Answer 22

Suspended sensory level with sacral sparing. “Shawl” loss of pain and temperature with preservation of vibration and position sense.

Question 23

What are the sensory defects in Anterior Spinal Artery Occlusion?

Answer 23

• Thoracic level of sensory loss, without sacral sparing, to pain and temperature.
• Since the posterior or dorsal columns are preserved, vibration and position sense remain normal.

Question 24

What is the common cause of posterolateral syndrome?

Answer 24

Vitamin B12 deficiency

Question 25

What are the deficiencies seen in posterolateral syndrome?

Answer 25

Vibration and position sense are reduced or lost in the lower limbs, leading to unsteadiness and falling if the patient stands or walks in the dark, or with eyes closed. This is further exacerbated by a spastic paraparesis from involvement of the corticospinal tract. Pain and temperature sensation are not affected by this spinal cord syndrome

Question 26

Amyotrophic Lateral Sclerosis

Answer 26

ALS is a degenerative disease where upper and lower motor neurons are selectively and progressively destroyed, for unknown reasons.

Question 27

What are the neural deficits seen in ALS?

Answer 27

• Sensory pathways are not affected, bowel and bladder functions remain normal
• Fasciculations
• Diffuse weakness with UMN and LMN signs progresses without obvious cause

Question 28

Tabes Dorsalis

Answer 28

Lumbosacral dorsal roots become infected and inflamed, producing severe radicular pains in the lower limbs, described as lightning, electrical, or shocklike.

Question 29

What are the deficits seen in tabes dorsalis?

Answer 29

The dorsal or posterior columns secondarily degenerate, so impairment of vibration and position sense in the lower limbs is noted. Eventually, most sensory fibers degenerate at these dorsal roots, creating loss of all sensation in the lower limbs, where reflexes are lost since the afferent reflex arcs are disrupted.