assessment of muscle tone

review- tone is

1. the tension attained at any moment between the origin and insertion of the muscle

2. assessed by how the muscle responds to passive stretch/elongation of the muscle

review- normal tone is

a state of slight residual contraction in normal muscle → steady-state or resting contraction AND reflects a balance between excitatory and inhibitory inputs to alpha MNs; low level alpha MN activity

what is the gradation from normal muscle tone

hypotonia ←> normal muscle tone ←> hypertonia

hypertonia: velocity independent (rigidity) and velocity dependent (spasticity)

what is hypotonia/hypotonicity

1. decreased or low resistance to movement, usually associated with diminished deep tendon reflexes (DTRs)

2. extremities will feel limp and heavy

3. joint stability is often a problem (ex: subluxed shoulder s/p CVA)

what is flaccidity

no muscle tone, no resistance to stretch

what is the clinical pearl for pt with hypotonia

1. pts will need joint and limb protection

   1. possible bracing or sling

   2. guarding of the involved limbs

what is hypertonicity

increased resistance of the muscle within passive elongation

what is hypertonicity due to

an UMN lesion → increased alpha motor neuron activity when the muscle is at rest

is hyper or hypotonicity more chronic

usually hypertonicity is more chronic in longer term than hypotonia following a stroke

hypertonicity is associated with hyperreflexia (increased DTRs) due to

loss of corticospinal inhibition with increased response from muscle spindle and/or cerebral lesion that disinhibits the reticulospinal and/or vestibulospinal tracts

what is rigidity

1. heightened resistance to passive movement of limb that is independent of velocity of stretch and relatively uniform throughout the ROM of that limb → co-contraction of the agonists and antagonists

   1. often seen in pts with Parkinsons and basal ganglia lesions

what is spasticity

1. a motor disorder characterized by velocity-dependent increase in resistance to passive stretch in a muscle group

   1. resistance to stretch is low during slow stretch

   2. resistance to stretch is high during fast stretch

where is spasticity usually observed

1. in either the flexors or extensors of a given joint, but not both → on just one side of a joint

   1. if both flexors and extensors of a given joint have high tone then you would observe rigidity

which muscles are impacted more frequently than other muscle groups in spasticity

anti-gravity muacles

does increased tone/spasticity = increased weakness or decreased function

no!

what is the overall incidence rate of spasticity post-CVA

between 30-80%

-some sources suggest that spasticity is more prevalent in younger vs older pts, those with higher NIHSS scores

-general rule→ spasticity comes on within the 1st month and lasts at least a year

where is more spasticity usually seen in

UE

where is spasticity more severe in

ankle, wrist, shoulder, elbow

what are additional influences on muscle tone

1. stress and anxiety

2. meds

3. general health

4. pain

5. position of the pt→ head in midline, body should be supported and relaxed

6. pt’s level of arousal or alertness

7. environmental influences- temperature (cold increases tone), humidity

what are the muscle tone trends in acute care

lower tone = flaccid paralysis

want to prevent disuse

immobilization in shortened position = contracture = spasticity

what are the muscle tone trends in rehab unit

plastic rearrangement = changes in spinal reactivity and supraspinal command = overactivity = spasticity

what should you know about common patterns of spasticity in UE

know that there are different patterns

what are common LE postures with spasticity

1. adducted thigh

2. flexed knee

3. extended knee

4. plantar flexed foot/ankle

5. equinovarus foot

6. striatal toe (extended big toe)

7. flexed toe

what is clonus

rhythmic pattern of contraction occurring at a rate several times per second. demonstrated by a sudden stretch of muscle

how do you test for clonus

1. apply a quick stretch to PFs or wrist flexors

2. maintain end range stretch

how do you document clonus

1. clonus is present or absent

2. report the number of “beats” or oscillations

3. sustained vs non-fatiguing clonus

what is rigidity

increased resistance to passive movement of a limb that is independent of the velocity of stretch and relatively uniform throughout the ROM of that limb

what are the 2 types of rigidity

1. cogwheel - bouncy whole way through

2. lead pipe- sustained

how to test for rigidity

1. perform PROM with pt relaxed

   1. feel for resistance to movement throughout arc

   2. normally in both flexors and extensors (both sides of joint)

   3. cogwheel - tremor in the movement

examination of ROM and tone

1. ask pt to perform active ROM of a given segment

   1. (have them move their uninvolved segment then involved segment or ask to move both at same time)

2. if you observe limited AROM in segment, then move segment passively through their ROM to determine if they have limited PROM due to potentially: rigidity, bony block, or pain

3. if you “clear” the pt’s ROM and verify there is no rigidity, bony block, or pain then move to perform Modified Ashworth Scale (MAS)

what is the Modified Ashworth Scale (MAS)

1. start in full shortened ROM of muscle being tested

   1. ex: full elbow flexion for testing elbow flexors

2. slowly go to full PROM of muscle - assess and note position

   1. ex: move passively slowly to full elbow extension

3. return to start position

   1. ex: bring back to full flexion

4. move arm quickly (over 1 sec) to full ROM passively

   1. quickly bring to full ext over 1 sec

   2. feel for resistance or catch- note then grade

what is a score of 0 on the MAS

no increase in muscle tone (normal)

what is a score of 1 on the MAS

slight increase in muscle tone, manifested by a catch and release OR by minimal resistance at the end of the ROM

what is a score of 1+ on the MAS

slight increase in muscle tone, manifested by a catch, followed by minimal resistance through the remainder (less than half) of the ROM

what is a score of 2 on the MAS

more marked increase in muscle tone through most of the ROM(1/4 to 1/3 through movement), but affected parts easily moved

*no catch

what is a score of 3 on the MAS

considerable increase in muscle tone, passive movement difficult but can get through full ROM

what is a score of 4 on the MAS

affected part(s) rigid in flexion or extension (can’t move through fast velocity)

what does the modified tardieu scale test

spasticity

-records the angle of “catch” during fast component and allows you to give a clonus grade

how can the modified tardieu scale be helpful

1. angle of muscle reaction (bigger = better)

   1. R1 = the angle of catch following fast velocity stretch

   2. R2= PROM following a slow velocity stretch

2. the angle the muscle stretches to passively (R2) - the angle of catch (R1) helps distinguish between contracture vs spasticity

   1. if number is smaller = most likely contracture

   2. if the number is bigger= most likely spasticity

what are 2 screens for UE and LE spasticity

1. pronator drift test

2. pendulum test

what is the pronator drift test

hold arms in front and see if they turn

-can’t determine if due to weakness or tone

what is the pendulum test

passively move knee from flex to extension then suddenly release

-should swing several times

-if doesn’t then most likely have diminished movement (high tone)