Muscle Tone and Spasticity

Question 1

Muscle Tone

Answer 1

-resistance to stretch

Question 2

Flaccidity

Answer 2

-no resistance
-LMN lesions and acute CNS motor tract lesions (spinal shock)

Question 3

Hypotonia

Answer 3

-abnormally low resistance
-LMN lesions and acute CNS motor tract lesions (spinal shock)

Question 4

Spasticity

Answer 4

-hypertonia and hyperreflexia
-velocity dependent stretch reflexes (increases with higher velocities)
-UMN lesion
-chronic motor tract lesions

Question 5

Rigidity

Answer 5

-constant resistance to passive movement

Question 6

Cogwheel Rigidity

Answer 6

-rigidity from basak ganglia disorders
-stop and start movements (gegenhalten)

Question 7

Decerebrate Posturing

Answer 7

-damage to brainstem between midbrain and pons
-Extension everywhere (not hands)

Question 8

Decorticate Posturing

Answer 8

-damage to superior midbrain or cortex
-Extension LE and flexed UE

Question 9

Spasticity Contributions

Answer 9

-neurological
-contracture/atrophy
-muscles and tendons becoming stiff
-reduced sarcomeres

Question 10

Supra-Segmental Spasticity

Answer 10

-descending pathways become hyperactive when tract is interrupted @ corona radiata, cortex or internal capsule
-must include premotor cortex
(corticoreticular tracts) and Anterior limb of internal capsule (sensory fibers)

-inhibitory system (dorsal reticulospinal tract, Reticular formation) controlled by premotor fails, excitatory (medial reticulospinal and vestib) less controlled

Question 11

Segmental Spasticity

Answer 11

-increased excitability of spinal stretch reflex and and gamma motor
-dysfunction of spinal inhibitory mechanisms (1a presynaptic, 1a reciprocal, 1b nonreciprocal)

Question 12

Ia Presynaptic Inhibition

Answer 12

-in muscle spindles
-mediated by GABA
-immobilization causes changes in control of Ia

Question 13

Ia Reciprocal Inhibition

Answer 13

-Ia afferents of agonist inhibits antagonists
-inhibits cocontraction

Question 14

Ib Non-reciprocal inhibition

Answer 14

-GTO
-inhibit MNs of homonymous muscles

Question 15

Renshaw Cell Inhibition

Answer 15

-interneurons inhibit homonymous and synergistic MNs
-inhibit gamma MNs and 1a interneurons

Question 16

Increasing Fusiotor Drive

Answer 16

-y MNs cell bodies in ventral horn
-info from reticular formation to
increased muscle spindle (a gamma contraction) sensitivity and hyperactivity

-also myoplasticity

Question 17

Myoplasticity

Answer 17

Adaptation changes in muscle length and receptor sensitivity

Question 18

Neuroplasticity

Answer 18

-reorganization of spinal circuits
-increased axons, sensitivity, enhanced reflexes (babinski)

Question 19

Spasticity Triggers

Answer 19

-nociception
-touch
-visceral receptors

Question 20

Measure of Spasticity

Answer 20

-modified ashworth scale
-PROM

Question 21

Clonus

Answer 21

Repetitive reflex contraction of a single muscle

Question 22

Clasp Knife Phenomenon

Answer 22

-catch and give
-catch delayed build up of resistance to stretch initially
-give is suppressed resistance