Lecture 12 - Deafferentation

Question 1

How did Flemish art depict sensation?

Answer 1

Using the Allegory of the Five Senses

Question 2

What is the Allegory of the Five Senses?

Answer 2

Painting depicting characters demonstrating the five senses

Question 3

What types of nerves do muscles have?

Answer 3

Muscle and sensory

Question 4

What is proprioception?

Answer 4

“Muscle sense”

Conscious perception of body position and movement in the absence of vision

Question 5

How does the proprioceptive pathway work?

Answer 5

Skin/joint/muscle spindle receptors receive info and send it up the spinal cord to the primary and somatic sensory cortex

Question 6

What are muscle spindles?

Answer 6

Stretch receptors located intramuscularly

Question 7

How do muscle spindles work?

Answer 7

Firing pattern corresponds with muscle length and changes in muscle length

Question 8

What is tendon vibration?

Answer 8

Stimulates muscle spindle firing by vibrating at 80-120 Hz to create the illusion of altered position and movement

Question 9

How can proprioception be measured?

Answer 9

Direction testing and matching testing

Question 10

What are the pros of direction testing?

Answer 10

A good indicator of whether a pathway is intact

Question 11

What are the cons of direction testing?

Answer 11

Can’t quantitatively measure acuity or position vs movement sense

Question 12

What is direction testing?

Answer 12

Movement of joints while the subject responds

Question 13

What are the pros of matching testing?

Answer 13

Keeps the pathway intact, is a measure of acuity, keeps position/movement possible

Question 14

What are the cons of matching testing?

Answer 14

Increased cognitive and perceptual demands

Question 15

What is matching testing?

Answer 15

Establishes target and the subject matches

Question 16

What is deafferentation?

Answer 16

A disorder where larger fiber sensory neurons no longer function

Question 17

What is another name for deafferentation?

Answer 17

Sensory neuronopathy

Question 18

What is the current incidence of deafferentation

Answer 18

Less than 20 known cases in the world

Question 19

What is the cause of deafferentation?

Answer 19

Selective apoptosis of 1a afferent neurons

Question 20

What causes apoptosis associated with deafferentation?

Answer 20

The cause is unknown. Possibly viral infection

Question 21

What are the signs and symptoms of deafferentation?

Answer 21

No sense of movement or touch
No tendon tap reflexes
No sense of body schema
Poor muscle coordination
Poor force control
Inability to walk
Pain and temperature senses intact

Question 22

What is body schema?

Answer 22

Concept of the body, full body representation of self.

Question 23

How can deafferentation be simulated?

Answer 23

Ischemic nerve block or dorsal rhizotomy

Question 24

How do ischemic nerve blocks simulate deafferentation?

Answer 24

By placing a tourniquet to slowly stop blood flow so enough blood allows the motor neurons to work but not the sensory neurons

Question 25

How do dorsal rhizotomies simulate deafferentation?

Answer 25

By cutting off afferent nerves to prevent sensory info from going to the brain

Question 26

How can deafferentation be treated?

Answer 26

Physical therapy, strategy training, and stem cell therapy

Question 27

How can physical therapy be used to treat deafferentation?

Answer 27

By using passive movement and ROM to reduce contractures from inability to walk

Question 28

How can strategy training be used to treat deafferentation?

Answer 28

By teaching patients to compensate with vision

Question 29

How can stem cells be used to treat deafferentation?

Answer 29

By attempting to get cells to differentiate into neurons

Question 30

What are some limitations of physical therapy in deafferentation?

Answer 30

It is unable to bring back proprioception

Question 31

What are some limitations of strategy training?

Answer 31

Patients lose focus of surroundings and fatigue to enable constant focus