0731 - Neural Compression Syndromes I

Question 1

What are the 3 main spinal cord pathways to know?

Answer 1

Motor pathway (cortico-spinal tract). Follows 80/10/10 crossing pattern, with crossing in medulla (pyramidal decussation - 80%) and at level of synapse (10%).
2 Sensory pathways -
Dorsal column (Touch etc - Gracile and cuneate, synapse in Nn Gracilis/Cuneatus, cross to contralateral medial lemniscus).
Spinothalamic - Pain and temp (lateral) crude touch/firm pressure (ventral). Cross immediately and synapse in thalamus.

Question 2

What area should you touch to test dermatome C2?

Answer 2

Back of the head

Question 3

What area should you touch to test dermatome C3?

Answer 3

Back of the neck

Question 4

What area should you touch to test dermatome C5?

Answer 4

Lateral upper arm

Question 5

What area should you touch to test dermatome C7?

Answer 5

Middle finger

Question 6

What area should you touch to test dermatome T4?

Answer 6

Nipples

Question 7

What area should you touch to test dermatome T10?

Answer 7

Umbilicus

Question 8

What area should you touch to test dermatome T6?

Answer 8

Xyphoid process

Question 9

What area should you touch to test dermatome L3?

Answer 9

Kneecap

Question 10

What area should you touch to test dermatome L5?

Answer 10

Lateral ankle, Big Toe

Question 11

What area should you touch to test dermatome S1?

Answer 11

Heel, lateral aspect of foot.

Question 12

Which nerve root carries the biceps jerk reflex?

Answer 12

C5 (6)

Question 13

Which nerve root carries the brachioradialis reflex?

Answer 13

C6

Question 14

Which nerve root carries the Triceps jerk reflex?

Answer 14

C7

Question 15

Which nerve root carries the finger jerk reflex?

Answer 15

C8

Question 16

Which nerve root carries the knee jerk reflex?

Answer 16

L4

Question 17

Which nerve root carries the ankle jerk reflex?

Answer 17

S1

Question 18

What myotome controls the intrinsic muscles of the hand?

Answer 18

T1

Question 19

What is the difference between upper and lower motor neurons

Answer 19

Upper - brain to spinal grey matter, via corticospinal tract.
lower grey matter (ventral horn) to muscle.

Question 20

How can you distinguish between upper and lower motor neuron lesions? Why is this important?

Answer 20

Upper - enhanced stretched reflexes with increased tone (no longer modulated by upper). “spastic” gait - arm flexes up (too many flexors), but leg wont flex (too many extensors), so need to swing it out. Positive Babinski reflex with minimal atrophy.
Lower - floppy, flaccid, lost stretch reflexes, reduced muscle tone/atrophic muscle. Footdrop.
Allows you to see where you should do your imaging studies.

Question 21

What are the symptoms of a cord lesion?

Answer 21

Dermatomes and myotomes do not work below the level of the lesion (vertical level)
Different spinal cord structures can be affected, allowing you to deduce the type of lesion etc.

Question 22

How does a transverse cord lesion present?

Answer 22

All pathways are cut, so complete loss of vibration/position (dorsal), pain and temp (spinothalamic) and motor (corticospinal) below level innervated by lesion area.

Question 23

How does a hemicord (one side) lesion present?

Answer 23

Loss of ipsilateral vibration and position sense (dorsal columns haven’t crossed yet), ipsilateral motor loss (corticospinal largely crossed at pyramids, only 10% would cross at level innervated), and CONTRAlateral pain and temperature (spinothalamic crosses almost immediately on entering cord), below level innervated by the lesion.

Question 24

What is cauda equina syndrome?

Answer 24

Dysfunction of most of the descending nerve roots within lumbar spinal canal. Most common from central lumbar disk prolapse, epidural metastasis, benign tumour, in that order.
Typical features of sacral pathology - Distended, atonic bladder, loss of bowel tone, loss of erectile function, and maybe weakness in sacral myotomes in leg.

Question 25

How are cauda equina syndromes and radiculopathies caused by herniated (slipped) disks?

Answer 25

Cauda equina syndrome usually central disk prolapse (into main part of spinal canal), but radiculopathy usually lateral disk prolapse (impinging on nerve root that is exiting). Herniated disk not only cause.

Question 26

What is a radiculopathy? 2 most common causes?

Answer 26

Nerve root pathology. Compression at neural exit foramen (cervical or lumbar) or compression of descending root within central canal (lumbo/sacral)

Question 27

What are the symptoms of a radiculopathy?

Answer 27

Sensory - dermatome pain or sensory loss/change. Motor - LMN weakness in affected myotome, attenuation of tendon reflex. Associated - Back pain, lumbar/cervical muscle spasm, postural change.

Question 28

Relationship between nerve root and disk in radiculopathy?

Answer 28

Typically, Nerve root affected is the one associated with lower vertebra - e.g. L4/5 disk impinges L5 nerve - gets it while it is descending. Nerve roots usually leave via upper half of transverse foramen, so herniated disk gets it before it leaves but after it has come off the spinal cord.

Question 29

What are the 5 terminal nerves/branches of the brachial plexus?

Answer 29

Anterior (to subclavian artery) - musculocutaneous, median, ulnar Posterior - Axillary, Radial.

Question 30

What is the root supply of the musculocutaneous nerve?

Answer 30

C56

Question 31

What is the root supply of the median nerve

Answer 31

C6-T1

Question 32

What is the root supply of the ulnar nerve?

Answer 32

C8,T1

Question 33

What is the root supply of the Axillary nerve?

Answer 33

C5

Question 34

What is the root supply of the Radial nerve?

Answer 34

C5-8

Question 35

What is the difference between a mononeuropathy and a polyneuropathy?

Answer 35

Mononeuropathy - individual nerve lesion, often compressive. Poly/peripheral neuropathy - Generalised disease of most of the nerves, with the longer nerves most prominently affected.