Motor Control Impairment: Tone & Spasticity [Guest Lecture]

Question 1

Describe the ICF Model

Answer 1

International Classification of Functioning, Disability, and Health

Health condition Body function/Structure <> Acitivities <> Participation Environment <———> Personal Factors

Question 2

Term: Multiple muscle activation

Answer 2

Synergy

Question 3

Term: Resistance offered by muscles when passively lengthened

Answer 3

Muscle Tone

“Stiffness”

Question 4

Describe muscle tone in “normals”

Answer 4

Uniform resistance at all speeds

Question 5

Term: Diagnostic indicator of UMN issue

Answer 5

Hypertonicity

Question 6

Term: UMN or LMN issue

Answer 6

Hypotonicity

Question 7

Term: Velocity dependent

Answer 7

Hypertone

Question 8

Structure: contains CT capsule, intrafusal mm fibers, gamma MN axons, sensory axons

Answer 8

Muscle Spindle

Question 9

Describe what muscle spindles provide a window into

Answer 9

The CNS for testing

For movement in those you can’t move on their own (use tone to one’s advantage)

Question 10

Structure: contracts edges of muscle spindle

Answer 10

Gamma motor neuron

Question 11

Structure: Endingin central region of intrafusal fibers

Answer 11

Sensory axons/afferents

Question 12

Structure: primary sensory ending

Answer 12

Type 1a

Question 13

Strucutre: Secondary sensory ending

Answer 13

Type 2

Question 14

Describe the type of channels in muscle spindles and how they propagate AP

Answer 14

Muscle spindles contain stretch sensitive channels

When the mm is streatch the channels release Ca++ which initiates the AP

Question 15

Structure:

• Sensitive to LOW amplitude and HIGH velocity
• Results in autogenic FACILITATION and reciprocal INHIBITION

Answer 15

Type 1a

Question 16

Structure:

• Sensitivie to SLOW, SUSTAINED stretch
• Activation less clear, complex polysynpatic respose

Answer 16

Type 2

Question 17

Structure: Innervate intrafusal fibers, cell bodies in ventral horn of SC

Answer 17

Gamma motor neuron

Question 18

Structure: Part of voluntary movement, NOT involved in stretch reflex pathway

Answer 18

Gamma motor neurons

Question 19

Describe alpha gamma coactivation

Answer 19

voluntary contraciton of mm is controlled by alpha motor neurons. In order to keep the mm spindles taught/same length as the regular mm gamma motor neurons must be activated to contract the edges of the mm spindle and alter their length accordingly

Question 20

Term: Loss of normal alpha-gamma coactivation

Answer 20

Hypotonia

Slack spindle, no input

Question 21

Describe what methods you could use to assess hypotone

Answer 21

• Passive motion
• Relaxed posture ex. hand could have some arch to it
• Could present as weak contraction with difficulty maintaining contraction and decreased proprioception

Question 22

Term: velocity dependent hypertonia or hyperreflexia

Answer 22

Spasticity

Question 23

Term: Severe, constant hypertonia

Answer 23

Rigidity

Question 24

Describe the neural cause of hypertonia

Answer 24

Alpha motor neurons are more senstive/hypersensitized to input due to

• increased excitatory inputs
• decreased inhibitory inputs
• new synapses

Thus minimal input from the Type 1a afferents can result increased contraction/tone/resistance

Question 25

Location: pathology of hypertonicity

Answer 25

Located at the alpha motor neuron (due to it’s hypersensitivity)

Question 26

Describe the non-neural cause of hypertonia

Answer 26

Immobilization or decreased use of mm can effec the visco-elastic properties of mm resulting in fibrosis/contracture, atrophy, or free Ca++ in motor fibers all of which can contribute to hypertonicity