Measuring Muscle Tone in Children Flashcards
Characteristics of hypotonia
Lack of resistance to passive movement
Decreased strength/Poor definition of muscles
Decreased activity tolerance
Decreased motor skill development
Rounded shoulder posture with a tendency to lean onto supports
Hypermobile joints
Increased muscle f lexibility
Poor attention and motivation
How to examine hypotonia?
Subjective in nature/process of exclusion following muscle biopsies and imagine
Examining hypotonia - Observation
- Do they look floppy?
- Do they have anti-gravity movements of the head and limbs (prone, vertical, supine)?
- Do they have a frog-legged posture? (hips abducted and externally rotated)
Examine hypotonia - Palpation
- Soft, pliable musculature
- Excessive ROM
Hypertonic –>
spasticity, dystonia, rigidity
Hyperkinetic –>
- Chorea
- Dystonia
- Athetosis
- Myoclonus
- Tremor
- Tics
- Stereotypies
Negative –>
- weakness
- Selective Motor Control
- Ataxia
- Dyspraxia
- Bradykinesia
- Balance
What is hypertonia?
Abnormally increased resistance to externally imposed movement about a joint
What are hyperkinetic movements?
Any unwanted excess movement
Negative motor signs in CP
Insufficient muscle activity or insufficient control of muscle activity
Movement Disorders in CP
- Hypertonia
- Hyperkinetic Movements
- Negative Motor Signs
Spasticity Definition
Velocity-dependent resistance of a muscle to stretch presenting with one or both of the following clinical signs
Resistance to externally imposed movement increases with increasing speed of stretch and varies with the direction of joint movement
Resistance to externally imposed movement rises rapidly above threshold speed or joint angle
Review physiology of spasticity on slides 16 and 17
Reticulospinal Tract
Inhibits muscle tone
Vestibulospinal tract
Excites muscle tone of antigravity/extensor muscles
Damage to corticobulbar tracts in CP:
- Loss of reticulospinal inhibition of muscle tone
- Continued vestibulospinal excitation –> increased lower extremity extensor tone
Definition of Dystonia
Involuntary sustained or intermittent muscle contractions resulting in twisting and repetitive
movements and/or abnormal postures
What is hypertonic dystonia?
Resistance to externally imposed movements at low speeds (not dependent on velocity)
Simultaneous co-contraction (observed in rapid reversal)
Limb returns toward fixed involuntary posture
Triggered/worsened by voluntary movements of other body parts
Varies with level of arousal
No other detected spinal cord or peripheral lesion
Rigidity
Rarely reported in children
“Joint cannot be moved”
Resistance to passive movement is independent of posture and speed of movement
“Lead-Pipe”
Not specific to task or posture
4 Clinical Measures of Hypertonicity
- Observation
- Hypertonicity Assessment Tool
- Modified Ashworth
- Modified Tardieu
What is the Hypertonicity Assessment Tool?
7 item tool incorporating tasks of the bilateral upper and lower extremities
Developed for children 4-19 y/o
Purpose: to differentiate the different forms of
hypertonicity
How is the hypertonicity Assessment Tool Scored?
The presence at least one HAT item per
hypertonia subgroup (spasticity, dystonia, rigidity) confirms the presence of the that subtype
The presence of more than one subgroup confirms the presence of mixed tone
How is the Hypertonicity Assessment Tool Administered?
Position the child in supine
Child wears comfortable, unrestrictive, clothing
Hands placed gently on upper abdomen
Place roll under knees and pillow under head
What muscles should you consider when evaluating tone in the lower extremities?
- Hamstrings
- Gracilis
- Rectus Femoris
- Gastrocnemius
Modified Ashworth Scale
- Used most in pediatric research
- Many variations (Bohannen, Other formates score for hypotonia)
- Standard test positions for children
Modified Ashworth Grading
0: No increase in muscle tone
1: Slight increase in muscle tone (catch or minimal resistance) at end of ROM
1+: Slight increase in muscle tone (catch) followed by minimal resistance throughout the
remainder (< half ) of the ROM
2: More marked increase in muscle tone through most of ROM, but affected part easily
moved
3: Considerable increase in muscle tone, passive movement difficult
4: Affected part rigid in flexion or extension (immobile)
Validity of Modified Ashworth Scale
- Correlates with other measures of hypertonicity (Tardieu), function (GMFM), isokinetic
- High scores of scale do correlates with isokinetic measurements of resistance to stretch
Is Modified Ashworth Scale a TRUE measure of spasticity
Nope!
Does not discriminate dynamic versus passive components of spasticity/hypertonicity
Reliability of Modified Ashworth Scale
Reliability not well demonstrated in children; children with CP
inter-rater in elbow flexors and hamstrings (ICC > .75)
Intra rater in hamstrings (ICC >.75)
Other studies have lower inter and intra rater
reliability
Test-retest reliability varied greatly
Low to average reliability for elbow, wrist, hip add, hamstrings, plantar flexors of children with CP
Is Modified Ashworth Scale sensitive enough to measure smaller differences in Spasticity?
Nope
Modified Tardieu Procedure
Measure end-point range of motion to slow
velocity ROM after 3 reps=R2
Measure angle when feel “catch” on 3rd trial of
high velocity ROM = R1
Modified Tardieu Scoring
R2-R1 = dynamic component of spasticity
mTS = quantify quality of muscle reaction
Tarieu Quantification of Quality of Reaction
0 = No resistance throughout passive movement
1 = Slight resistance throughout passive measurement
2 = Clear catch at precise angle, interrupting passive movement and followed by release
3 = Fatigable clonus (<10 secs.) at precise angle
4 = Unfatigable clonus (>10 secs.) at precise angle
What does Modified Tardieu Scale do??
Assesses passive joint ROM at different speeds. to determine dynamic tone
Tardieu Scale Validity
- Implied in MAS studies
- Responsive to change
Tardieu Scale Reliability
Reliability = .70 or greater = acceptable measure in children with CP
Improves after training
Other frequently used measures of “spasticity/hypertonicity”
Palpation –firm feel to mm belly
Quantification of DTR
Reflex testing Measures hyperactive stretch reflex
NOT velocity dependent
Quantification of Clonus
Measures neuro hyperexcitability of mm
NOT velocity dependent
Considerations for measuring “tone”
Dynamic component (response to mm stretch)
Best done with Tardieu scale
Passive component –changes in tissue mechanics
Resting state of the muscle
Environment, time of day, behavioral state, level of
excitement, amount of effort
