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Application of Muscle Tone EMG:How to evaluate rigidity and spasticity objectively.

筋電計

Application of Muscle Tone EMG

Supervisor: Saburo SAKODA, Director, National Hospital Organization Toneyama National Hospital

Co-supervisor: Takuyuki Endo,Doctor, National Hospital Organization Toneyama National Hospital

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Establishment of objective evaluation

of muscle tone

Evaluation of muscle tone has problem that its result is unstable and has the individual differences among testers. Hence, we developed the evaluation equipment that same results can be obtained by anyone.

“Muscle tone EMG” evaluate rigidity and spasticity by bending and stretching subject’s arms as the current diagnostic methods. Therefore, anyone can use this apparatus.

Figure 1: Muscle Tone EMG (MTM-05)

This quantifies a part of “Sansation of palpation” decided by tester’s experience until now, and realizes high objective evaluation.

High reproducibility evaluation

Application of Muscle Tone EMG １

Measurement is carried out along indicator referencing to an explaining screen; therefore, doctors out of them specialty,

nurses or paramedics and others, can get objective and high

reproducibility results without the examination experience.

Indicator

Figure 3: IndicatorFigure 2: Explaining screen

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Measurement Data

The measurement data outputted by this apparatus are as follows:• Electromyogram of biceps brachii muscle.• Electromyogram of triceps brachii muscle.• Elbow joint angle.• Elbow joint torque.

Figure 4: Surface electrodes and reference electrode

Electromyogram measured by surface electrodes set a t biceps and triceps brachii, and the reference electrode set at the opposite side of the arm’s wrist.

Application of Muscle Tone EMG

Figure 5: 0°position of elbow joint Figure 6: Maximum flexion point of elbow joint

Tester repeats bending and stretching the patient’s arm five times per a minute.

The sensor unit attached at the wrist measures the elbow joint angle and torque by using the gyro sensor and the load cells.

２

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Results (1.Electromygram)

Elb

ow

join

t a

ng

le

Bic

ep

sb

rac

hii

Tric

ep

sb

rac

hii

Time(Seconds)

Waveform of elbow joint angle

Waveform of biceps brachiiWaveform of triceps brachii

EMG Index

Figure.7 is the summary graph that electromyograms of the biceps and triceps brachii, and the elbow joint angle while tester was bending and stretching the subject’s arm five times per minute.

Figure 7: Result of measurement(electromyogram)

Maximum flexion point(120˚)

Maximum extension point(0˚)

(Refer to page 5)

Results (2. Elbow joint torque)

Figure. 8 is the result graph analyzed by extracting features from elbow joint torque-angle characteristics. The X axis represents elbow joint angle and the y axis represents elbow joint torque.

Application of Muscle Tone EMG３

Blue Line: Extension

Figure 8: Result of measurement(Elbow joint torque-angle characteristics)

Red Line: Flexion

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Comparison of results

Electromyogram

The results below are the result of a healthy volun teer and the result of a PD patient. There is a clearly differen ce in both graphs.

Figure 9.1: Comparison of results

Application of Muscle Tone EMG ４

Red line: flexion

Red line: flexion

Blue line: extension

Blue line: extension

Elbow joint torque-angle characteristics

Figure 9.2: Comparison of results(Elbow joint torque-angle characteristics)

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Reading rigidity from electromyogram

The waveform appears in the biceps brachii during steady state in a maximal extension (120˚), and it appears in the triceps brachii during steady in a minimum extension (0˚). The muscle is active in a fully extension in spite of a passive movement.

The characteristics of PD patients is below:

Figure 10:Comparison of electromyograms

EMG Index = A/B

EMG Index = D/C

A B

C D

Element for characterizing rigidity

Index from electromyogram: EMG IndexThe EMG waveform of a PD patient appears in a steady state. Therefore, the

feature value can be defined from it.

Figure 11: EMG Index

Application of Muscle Tone EMG

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Diagnostic information from

EMG Index

0

1

2

3

4

5

6

7

8

9

健常者 ＰＤ患者

EMG

In

de

x o

f b

ice

ps

bra

ch

ii Cut off value 1.1

< 1.1 1.1 <=SpecificitySensitivity

Healthy volunteers

31 8Specificity

80%

PD patients 4 46Sencitivity9

2%

EMG Index can screen PD patients.

*1: This data is experimental results targeted at 24 healthy volunteers (18 males, 6 females, Average age: 67.6 years old) and 27 PD patients equal to UPDRS3 (16 males, 11 females, Average age: 70.0 years old)

*1 Chart 1: Sensitivity and specificity of EMG Index

PD patientsHealthy volunteers

Figure 12: Sensitivity and specificity of EMG Index

Red line: flexion

Blue line: extension

Reading rigidity from elbow joint

torque-angle characteristics

On the other hand, on the graph for a PD patient, the flexion line separates from the extension line, and these inclinations are large. Hence, it indicates that the muscle is hard, and its tone is high.

The X axis represents elbow joint angle(degree) and the Y axis represents elbow joint torque(Nm).

On the graph for a healthy volunteer, the flexion line overlaps with the extension line. In addition, these inclinations are small. Therefore, it indicates that the muscle is soft, and its tone is low.

Figure 13: Comparison of Elbow joint torque-joint characteristics

Application of Muscle Tone EMG ６

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Element for characterizing rigidity

Index from elbow joint torque-angle characteristics:

Elastic coefficientsElastic coefficients are calculated by estimating t he slope of the

regression line for both flexion and extension. It can be used for estimating rigidity.

Figure 14: Elastic coefficients

r=0.75, p<0.001 r=0.70, p<0.001

Diagnostic information from

Elastic coefficients

L L

※１※１

If Elastic coefficients are large, even UPDRS is la rge.

Application of Muscle Tone EMG ７

Figure 15: The relationship of Elastic coefficients to UPDRS rigidity score

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The difference of Bias: Torque values averaged at a certain joint angle.

r=0.80, p<0.001

Element for characterizing rigidity

Index from elbow joint torque-angle characteristics:

Sum of the difference of Bias

The differences of Bias at 30˚, 60˚, and 90˚ were calculated and the resulting values were summed (Sum of the Difference of Bias).

L

※１

Figure 16: The relationship of “Sum of the difference of Bias” to UPDRS

An actual display of results:Elastic coefficients and sum of the difference of Bias

Figure 17: Display of elastic coefficients and sum of the difference of Bias

An actual display of elastic coefficients and sum of the difference of Bias is as below:

Application of Muscle Tone EMG ８

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An actual display of results:Elbow joint torque-angle characteristics

Figure 18: Display of elbow joint torque-angle characteristics

Ke: 1.796[N*m/rad*kg]

Sum of the different of Bias: 2.256[N*m/kg]

Ke: 0.749[N*m/rad*kg]

Sum of the different of Bias: 0.070[N*m/kg]

Figure 19 is the results of undergoing DBS for PD patient.

It follows from this quantitatively that rigidity has been reduced markedly.

Red: flexion

Blue: extension

Black: steady

ID:05-3

Assessment of treatment effect

～DBS(Deep Brain Stimulation)

Figure 19: Treatment effect of DBS

Application of Muscle Tone EMG ９

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0

0.2

0.4

0.6

0.8

1

1.2

Ela

stic

co

eff

icie

nt

in

exte

nsi

on

[N

*m/r

ad

*kg

]

Ａ

Ｂ

Ｃ

Ｄ

0

0.5

1

1.5

2

2.5

3

3.5

4

Sum

of

the

diff

ere

nc

e o

f B

ias

[N*m

/kg

]

Ａ

Ｂ

Ｃ

Ｄ

Evaluation example of medical efficacy (measured 2 PD patients) :It follows from this that treatment effect was exhibited quantitatively.A,B：Dopamine agonist 1mg/day

C,D：L-dopa100mg/day

ID:05-3

Assessment of treatment effect

～ Antiparkinsons

Figure 20: Treatment effect of antiparkinson

Reading spasticity from elbow joint torque-angle

characteristics

Left graph is for a healthy person. Right one is for a stroke patient and caught “Clasp-knife response”.

Red line: flexion

Blue line: extension

The graph of stroke patient shows that red lines are separated from blue line at joint angles from 0 to 60˚, but not separated at joint angles from 60 to 120˚. This is the graph that capture so-called Clasp-knife response visually.

Figure 21: Characteristic of spasticity(Clasp-knife response)

（左被殻出血、MAS2）

Application of Muscle Tone EMG １０

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Diagnostic information from

evaluation Index of spasticity

Figure 22: The new method for determining the prese nce or absence of spasticity.

1. Approximating the elbow joint torque-angle charac teristics by a cubic function.

2. Drawing a line connecting two points on the appro ximating curve in the end of angle range.

3. Counting the number that there are the area above line.4. Deciding the maximum area as maximum value of int egral(MVI).

Without the area above line:

passive

With the area above line:

positive

Breakdown of result as below:Total 24 cases – 18 men, and 6 women, mean age of 57 .5±14.6, cerebral hemorrhage 16 patients of cerebral hemorrhage, and 8 patients of cerebral infarction, MAS 0:5 patients, MAS 1:6 patients, MAS 1+:5 patien ts, MAS 2:3 patients, MAS 3:3 patients

Evaluation by

this criteria With

spasticity

Without

spasticity

Sensitivity

SpecificityEvaluation by

MAS

With

spasticity16 3

Sensitivity

84.2%

Without

spasticity5 24

Specificity

82.8%

We defined the criteria of evaluation index of spas ticity as Chart 2.The results of the clinical evaluation by this crit eria shows high sensitivity and specificity.

Chart 2: Criteria of evaluation index of spasticity Chart 3: Result of the clinical evaluation by this criteria

Criteria of evaluation index of spasticity

Display of results of spasticity evaluation shows n umbers of the positive and MVI.

Application of Muscle Tone EMG １１

Class Criteria of evaluation index of spasticity

A The positive appeared 5 in 5 times.

B The positive appeared 2 to 4 in 5 times

C The positive appeared 1 in 5 times

D The positive did not appear.

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Display of results of spasticity evaluation

MVI in flexion MVI in extension

Figure 23:Display of results of spasticity evaluation

If the number of the positive appears from 2 to 5 i n 5 times, and MVI is 0.3 and over, there’s a possibility that the patient has spasticity.

Number of the positive in flexion

Number of the positive in extension

Application of Muscle Tone EMG １２

Print image

Measurement results are stored in a USB Drive as JPEG image.

Figure 24:Print image

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UPDRS Part III – 22:Rigidity(Judged on passive movement of major joints with

patient relaxed in sitting position. Cogwheeling to be ignored.)

0 = Absent.

1 = Slight or detectable only when activated by mirror or other

movements.

2 = Mild to moderate.

3 = Marked, but full range of motion easily achieved.

4 = Severe, range of motion achieved with difficulty.

Clinical evaluation of abnormal muscle tone:Judged on passive movement of major joints

UPDRS: Unified Parkinson Disease Rating Scale

Chart 4: UPDRS

MAS: Modified Ashworth Scale

0: No increase in muscle tone.

1: Slight increase in muscle tone, manifested by a catch and

release or by minimal resistance at the end of the range of

motion when the affected part(s) is moved in flexion or

extension.

1+: Slight increase in muscle tone, manifested by a catch,

followed by minimal resistance throughout the remainder

(less than half) of the ROM.

2: More marked increase in muscle tone through most of the

ROM, but affected part(s) easily moved

3: Considerable increase in muscle tone, passive movement

difficult

4: Affected part(s) rigid in flexion or extension

Chart 5: MAS

Application of Muscle Tone EMG １３

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References

No. Titles Publisher Authors

1

A novel method for systematic analysis ofrigidity in Parkinson’s disease.

Movement Disorders24(15);2218-2224,2009

T. Endo, R. OkunoM. Yokoe, K. AkazawaS. Sakoda

2

Parkinsonian Rigidity Shows VariableProperties Depending on the Elbow JointAngle

Parkinson’s Disease2013;2013:258374

T. Endo , T. HamasakiR. Okuno, M. YokoeH. Fujimura , K. AkazawaS. Sakoda

3

Novel Methods to Evaluate Symptomsin Parkinson's Disease– Rigidity and Finger Tapping

Diagnostics and Rehabilitationof Parkinson's DiseaseInTech, December 07, 2011

T. Endo, M. YokoeH. FujimuraS. Sakoda

4

Parkinsonian Rigidity Depends on theVelocity ofPassive Joint Movement

Hindawi Publishing CorporationParkinson’s DiseaseVolume 2015, Article ID 961790, 4pages

T. Endo, N.YoshikawaH. FujimuraS. Sakoda

Application of Muscle Tone EMG １４

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Application of Muscle Tone EMG:How to evaluate rigidity and spasticity objectively.

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