Neuro: 2.04 - Somatosensory System Review - Brainstorm

Front 1

The dorsal column receives what kind of information?

Back 1

- Fine touch
- Vibration
- Limb position (proprioception)
- Motion

Front 2

Anterolateral system receives what kind of information?

Back 2

- Pain
- Temperature (cool and warm)
- Some crude touch

Front 3

What are the major tracts of the dorsal column?

Back 3

- Fasciculus Gracilis (lower body)
- Fasciculus Cuneatus (upper body)
- At medulla, both enter medial lemniscus

Front 4

What are the major tracts of the anterolateral system?

Back 4

- Spinothalamic tract
- Spinoreticular tract
- Spinomesencephalic tract
(other smaller tracts)

Front 5

How are the dorsal column and anterolateral system tracts placed in the spinal cord?

Back 5

- Dorsal column - dorsal / middle
- Anterolateral system - ventral lateral (funiculus)

Front 6

What are the pathways of the dorsal column? Destination?

Back 6

- 1 major pathway to medulla
- 1 major pathway to thalamus

Front 7

What are the pathways of the anterolateral system? Destinations?

Back 7

- Spinothalamic - thalamus
- Spinoreticular - reticular formation in medulla and pons
- Spinomesencephalic - midbrain PAG, superior colliculus

Front 8

Where do the fibers of the dorsal column cross over to the opposite side?

Back 8

In medulla - sensory decussation

Front 9

Where do the fibers of the anterolateral system cross over to the opposite side?

Back 9

In spinal cord and all along spinal cord at levels near where the primary afferents enter

Front 10

What are the results of damage to the dorsal columns in the spinal cord?

Back 10

Ipsilateral loss of tactile, vibration, joint position just below lesion

Front 11

What are the results of damage to the anterolateral systems in the spinal cord?

Back 11

Contralateral loss of pain and temperature by 2-3 segments below lesion

Front 12

What are the results of damage to the dorsal columns in the thalamus or cortex?

Back 12

Contralateral loss of tactile, vibration, joint position

Front 13

What are the results of damage to the anterolateral system in the thalamus or cortex?

Back 13

Contralateral loss of pain and temperature

Front 14

What is a lesion?

Back 14

A zone of localized dysfunction within the CNS or PNS

Front 15

Name?

Back 15

Fasciculus Gracilis in medulla

Front 16

Name?

Back 16

Fasciculus Cuneatus in medulla

Front 17

Name?

Back 17

Spinothalamic Tract in medulla

Front 18

Name?

Back 18

Spinal Trigeminal Nucleus in medulla

Front 19

Name?

Back 19

Spinal Trigeminal Tract in medulla

Front 20

Name?

Back 20

Medial Lemniscus in rostral medulla

Front 21

Name?

Back 21

Spinothalamic Tract in rostral medulla

Front 22

If you lesion one side of the spinal cord, what are the implications?

Back 22

- Ipsilateral loss of fine discrimination, joint position, vibration immediately below lesion
- Contralateral loss of pain and temp; loss is complete by 2-3 segments below lesion
- Minor: some loss of crude touch on contralateral side
- Patient presents with ALTERNATING sensory loss --> indicates unilateral lesion in spinal cord

Front 23

If patient presents with alternating sensory loss, what is probably wrong?

Back 23

Unilateral lesion in spinal cord

Front 24

How do you test light touch?

Back 24

Cotton swab, light finger touch

Front 25

How do you test 2-point discrimination?

Back 25

Paper clip, calipers, forceps

Front 26

How do you test vibration?

Back 26

Tuning fork

Front 27

How do you test joint position?

Back 27

Move digits, joints

Front 28

How do you test pain?

Back 28

Safety pin

Front 29

How do you test temperature?

Back 29

Cool metal (tuning fork), test tube w/ cold/warm water

Front 30

What is a rhizotomy?

Back 30

- Surgical cutting of dorsal roots (typically cut dorsal roots adjacent to affected dermatomes due to overlapping territories)
- Used for pain relief
- Cut dorsal roots that innervate affected dermatome

Front 31

What are the implications of a Rhizotomy?

Back 31

- Lose fine discrimination, joint position, vibration, and pain/temp in dermatomes of cut roots ipsilateral to lesion
- Pain often recurs after 3-4 months

Front 32

What is a cordotomy?

Back 32

- Surgical cutting of anterolateral fiber tracts in cord
- Used for pain relief (only for terminally ill)
- Cut at 2-3 spinal segments above dermatome where pain begins

Front 33

What are the implications of a cordotomy?

Back 33

- 1 side: lose pain and temp contralaterally
- 2 sides: lose pain and temp bilaterally
- Pain often recurs in 6 months (other pathways that must be carrying pain information)

Front 34

What are some possible causes of a peripheral nerve lesion?

Back 34

- Trauma
- Diabetes
- Neuropathy

Front 35

When there is a peripheral nerve lesion, what are the deficits?

Back 35

- Lack of fine discrimination, pain and temp. in skin, only in parts of limbs
- Ex: glove and stocking loss in several distant limbs

Front 36

What causes a glove and stocking loss of sensation?

Back 36

Peripheral neuropathy - most likely diabetes or metabolic disease

Front 37

Why do patients with diabetes often have peripheral neuropathy?

Back 37

- Sugar levels lead to decreased blood supply to extermities
- Multiple dermatomes affected

Front 38

What can cause the sensation loss shown above?

Back 38

Herniated spinal disk between L4-L5 roots (L5 nerve) - affects L4/L5/S1 dermatomes

Front 39

What are the implications of a complete cord transection?

Back 39

- Bilateral loss of all sensation (tactile and pain) below lesion
- Also, loss of motor control

Front 40

What can cause a complete cord transection?

Back 40

Trauma: fracture, dislocated vertebrae, cord compression
Penetrating injuries: bullet, knife wound
Disease: tumor expanding into cord

Front 41

What are the potential causes of anterior cord syndrome?

Back 41

- Fractured vertebrae - contusion of spinal cord
- Infarct (loss of blood supply) or ischemia from anterior spinal artery, embolism (blood clot) or compression of artery (disk herniation, bone fragments) --> necrosis of spinal cord tissue

Front 42

What are the implications of anterior cord syndrome?

Back 42

- Bilateral loss of pain and temperature below lesion
- Often weakness
- Usually spares dorsal columns - fine discrimination, vibration, joint position are OK

Front 43

What are the potential causes of posterior cord syndrome?

Back 43

- Posterior spinal artery interruption
- Tumor compression
- Trauma
- Tabes dorsalis (demyelination/degeneration from syphilis)

Front 44

What are the implications of a posterior cord syndrome lesion?

Back 44

- Loss of fine discrimination, vibration, joint position below lesion
- Pain and temp OK throughout body

Front 45

What does this picture show?

Back 45

- Tabes Dorsalis - from syphilis - light part is the area of demyelination and degeneration
- Causes posterior cord syndrome

Front 46

What are some potential causes of central cord syndrome?

Back 46

- Syringomyelia: tube-like enlargement of central canal from excess fluid; gliosis, cysts formed in central form of cord
- Hyperextension of cervical spine - damages center of cord

Front 47

What are the implications of a small lesion / central cord syndrome?

Back 47

- Cuts second order anterolateral fibers that cross cord
- Bilateral loss of pain and temp in dermatomes of spinal levels w/ lesions
- Small lesion usually spares dorsal columns and tactile sense and also spares anterolateral tracts and pain/temp below

Front 48

What are the implications of a large lesion / central cord syndrome?

Back 48

- Cuts second order anterolateral fibers that cross cord
- Bilateral loss of pain and temp in dermatomes of spinal levels w/ lesions
- Dorsal columns (bilateral loss of fine discrimination, joint position below lesion)
- Motor neurons in ventral horn (loss of motor control)
- Anterolateral tracts (bilateral loss of pain and temp)
- May get sacral sparing of sacral part of anterolateral tracts

Front 49

What happened to Christopher Reeve?

Back 49

Hyperextension of C2 level - fluid filled cyst in center of spinal cord

Front 50

What are the potential causes of a hemisection (Brown-Sequard Syndrome)?

Back 50

- Severe penetrating injury: bullet or puncture wound
- Tumor in spinal cord - compressing ascending pathways
- Multiple Sclerosis
- Meningitis
- Herniated disk

Front 51

What are the implications of a hemisection?

Back 51

- Fine discrimination and pain/temp loss on alternating sides
- Ipsilateral loss of tactile, vibration below lesion
- Contralateral loss of pain, temp by 2-3 segments below lesion
- Total loss of all sensation right at level of lesion
- Also ipsilateral paralysis, muscle weakness, and loss of muscle control

Front 52

What are the potential causes of a unilateral lesion in VPL or VPM of thalamus, or in cortex, or brainstem?

Back 52

- Stroke
- Hemorrhage
- Brain tumor
- Multiple Sclerosis
- Trauma that affects that part of brain

Front 53

What are the implications of a unilateral lesion in the VPL of thalamus?

Back 53

- Contralateral loss of fine discrimination
- Contralateral loss of pain and temperature in body
- Sensation in face is intact

Front 54

If both types of sensation are on the same side, what does this tell you?

Back 54

- Lesion must be superior to medulla because that's where posterior column fibers cross
- Lesion is on contralateral side to sensory deficits

Front 55

What are the implications of a unilateral lesion in VPM of thalamus?

Back 55

- Contralateral loss of fine discrimination
- Contralateral loss of pain and temperature in face and head
- Sensation in body is intact

Front 56

What are the implications of a unilateral lesion in the somatosensory I cortex as shown in the picture?

Back 56

- Contralateral loss of fine discrimination
- Contralateral loss of pain and temp.
- Location: arm and hand

Front 57

What are the implications of a unilateral lesion in the somatosensory I cortex as shown in the picture?

Back 57

- Contralateral loss of fine discrimination
- Contralateral loss of pain and temp.
- Location: face and tongue

Front 58

What are the implications of a brain stem lesion in lateral medulla?

Back 58

- Can interrupt both anterolateral pathway and spinal trigeminal tract or nucleus
- Loss of pain/temp in body on contralateral side
- Loss of pain/temp in face on ipsilateral side
- Loss of pain and temp in face on contralateral side

Front 59

If a brain stem lesion affects the entire medulla on one side, what are the implications?

Back 59

- Can interrupt both anterolateral pathway and spinal trigeminal tract or nucleus
- Loss of pain/temp in body on contralateral side
- Loss of pain/temp in face on ipsilateral side
- Loss of pain and temp in face on contralateral side
- Loss in fine touch in body on contralateral side

Front 60

Implications of the lesion shown above?

Back 60

Loss of vibration on right side of body below level of neck

Front 61

You have a patient that has suffered a gunshot wound that has completely disrupted the entire left half of the spinal cord at T6. What are the deficits this patient will most likely present with?

Back 61

- Loss of pain and temp from R leg
- Loss of 2-point discrimination from L leg

Front 62

A patient presents with the following symptoms:
- Loss of pain and temp on R half of body from neck down
- Loss of fine discrimination and vibration on R half of body from neck down
- CAT scan shows infarct
Where is the most likely site of the infarct?

Back 62

Left VPL nucleus of thalamus