Stålberg, EMG analysis - ccme.osu.edu - Analysis of... · • Motor units –total number –activation; ... •recruitment ... Stålberg, EMG analysis 6 10 mm from end‐plates

Stålberg, EMG analysis

1

Erik Stålberg

UppsalaSweden

What can we assess with EMG?

• Muscle membrane function - spontaneous

• Muscle fibre characteristics; diameter

• MU organization– number of fibers

– grouping

• N-M transmission

• Motor units– total number

– activation; pattern, fullnessStålberg

Parameters to quantify in Conc/Monopolar EMG

• spontaneous activity

• shape of individual MUPs

• jiggle

• recruitment (early, reduced)

• fullness at strong activation

• dynamic changes with time (fatigue)


2

Spontaneous activity in normal

• insertional activity

• end-plate noise

• ”nerve spikes”

• positive wave at end-plate zone

Visual scoringSpontaneous activity

from the muscle

FINDING• fibrillation potentials, psw• myotonic discharges• CRD• myokymic discharges• myogenic extra discharges

MEASURE AS

• #/ 10 recording sites

• or +, ++, +++, ++++ – few

– moderate

– abundant

• or– spontaneous or

– after provocation

Visual scoringSpontaneous activity

from the nerve

MEASURE AS

• #/ 10 recording sites

• or +, ++, +++, ++++ – few (per time unit)

– moderate

– abundant

• indicate– spontaneous or

– after provocation

FINDING• neuromyotonic discharges• myokymic discharges• muscle cramps• fasciculations• neurogenic extra discharges

Fib, PSW ?

Myotonic Disch. ?

CRD ?

Spontaneous activity in myopathyMuscular dystrophies

Myositis, IBM

Debrancher Glycogenosis

Acid Maltase Deficiency

Hyperkalemic per paralysis

Myotonic conditions

LGMD 1A

Nemaline myopathy

Myotubular myopathy

Mitochondrial myopathy

Carnitine Deficency

Hypothyroid myopathy

Rhabdomyolysis

Toxic - Chloroquine

- Alcoholic

- Statins

- Colchicine

Yes

No

No

Courtesy R.Liguori, modified


3

Fib, PSW ?

Myotonic Disch. ?

CRD ?


Myositis, IBM




Myotonic conditions

LGMD 1A

Nemaline myopathy

Myotubular myopathy


Carnitine Deficency


Rhabdomyolysis

Toxic - Chloroquine

- Alcoholic

- Statins

- Colchicine

Yes

No

Yes

Fib, PSW ?

Myotonic Disch. ?

CRD ?


Myositis, IBM




Myotonic conditions

LGMD 1A

Nemaline myopathy

Myotubular myopathy


Carnitine Deficency


Rhabdomyolysis

Toxic - Chloroquine

- Alcoholic

- Statins

- Colchicine

Yes

Yes

Yes

Fib, PSW ?

Myotonic Disch. ?

CRD ?


Myositis, IBM




Myotonic conditions

LGMD 1A

Nemaline myopathy

Myotubular myopathy


Carnitine Deficency


Rhabdomyolysis

Toxic - Chloroquine

- Alcoholic

- Statins

- Colchicine

Yes

No

Yes

Fib, PSW ?

Myotonic Disch. ?

CRD ?


Myositis, IBM




Myotonic conditions

LGMD 1A

Nemaline myopathy

Myotubular myopathy


Carnitine Deficency


Rhabdomyolysis

Toxic - Chloroquine

- Alcoholic

- Statins

- Colchicine

Yes

No

No


4

Conc. EMGsignals from 2 - 15 muscle fibers

Conc. EMGsignals from 2 - 15 muscle fibers

Stålberg

Central spike

Slow wave components

Monopolar EMGMonopolar EMG

Stålberg

Central spike

Slow wave components

Generation of a MUP


5

diameter50±5 µm

10 mm from end‐plates

Simulation studieseffect of rec. pos.effect of fiber size

normal sizeclose rec.

diameter50±5 µm


normal sizedist. rec.

diameter50±5 µm


Simulation studieseffect of rec. pos.effect of fiber size

normal sizeclose rec.


6


diameter40±15 µm

diam. variationclose rec.


diameter40±15 µm

diam. variationclose rec.

oppositeside of nmj

end of propat tendon

slowly propSFAPrepolarisation

T

T

T

T

duration

startat nmj

phase

Stålberg

T

T

T

Parameters used in MUP analysis

parameter significance measurement

• Amplitude # fibers/0.5mm peak-peak

• Area # fibers/2 mm within dur

• Duration # fibers in 2.5 mm slope criteria

• Thickness # close fibre area/ampl

• Size index MU size normalized thickness

• Phases temp dispersion 0-cross + 1

• Turns “ change in dir

• Irregularity “ length/ampl

• Rise time closeness to fibre neg-pos peak

• Satellites extreme delay late spike

• Jiggle n-m transm shape stabilityStålberg


7

This example: Multi MUP analysis

techniques to decompose a mixed signal into its constituents

Decomposition;

Stålberg

A

BC

500 uV

10 ms

Normal

Neuropathy

Myopathy

Multi-MUP analysis in different disorders

Stålberg


8

AmpLItu d e

Amplitude

Measured peak-peak

* note that jiggle will reduce mean amplitude (measured

after averaging)

Duration area


9

Area

Positive and negative signal segment between duration

cursors; mVmsec

C XE

LP

MO

TI Y

Phases, turns

Phases, turns

Way to express complexity

>4 phases = polyphasic

> 5 turns = complex, serrated

The jiggle


10

The jiggle The jiggle

The jiggle The jiggle


11

Jiggle in normal and abnormal MUPs

Stålberg

Normal

ALS

So, shall I use all these parameters??

Which one is best?

Let us look at the diagnostic power of a few parameters

Amplitude(Tib.ant.)

0.87

,13

polymyositis

ALS

Stålberg,Erdemunpublished

SD

SD

-2SD +2SD

Duration

0.88

.46

polymyositis

ALS



12

Area

.36

0,85

polymyositis

ALS


Reference valuesnecessary to separate abnormal from normal

This is a crucial point in quantitative EMG analysis

• mean, SD (# of SDs = Z-score)

• median, percentiles

• outliers

• combine different data (multivariate analysis, index)

A few examples

Lat vastus m

outlier

Combination of abnormally small and large MUPs (Hereditary distal myopathy)

Lat vastus m

Combination of abnormally small and large MUPs (Hereditary distal myopathy)

outliers


13

Interferencepattern

Methods

• recruitment analysis

• visual inspection (ampl, fullness)

• spectral analysis

• broad band filter analysis

• turns/amplitude analysis

• envelope, NSS, activity

Stålberg, Daube 2003

Myopathy

Normal

Neuropathy


14

Frequency bands in EMG, schematic

0

5

10

15

1 2 3 4 5 6 7 8 9 10 11 12

normal

0

5

10

15

20

1 2 3 4 5 6 7 8 9 10 11 12

neuropathy

0

5

10

15

1 2 3 4 5 6 7 8 9 10 11 12

myopathy

0-50 200-300 1000 Hz

0-50 200-300 1000 Hz

0-50 200-300 1000 Hz

“LUCIA”

EMG power spectrum

Neuropathy Normal Myopathy

mBiceps brachii

A Fuglsang-Frederiksen

Turns-Ampl (TA) analysis

normal neuropathymyopathy


15

MyopathyTib ant18446

IP MUP

Tib ant

Comparison of electrophysiological parameters

Parameters nm-j myopathy den/reinn axon loss CB central

SFEMG n n n

Conv MUP abn n n n

Conv IP n myo neur

Macro n n n n n

MUNE n n n n n

TMS n n n abn

Reasons for performing QEMG

• standardized way of measuring

• improved sensitivity

• results can be transferred– from one time to the other - follow up

– from one physician to the other

– from on lab to the other

• reliable results also from less experienced EMGers

• good during training

Documents

Stålberg, EMG analysis - ccme.osu.edu - Analysis of... · • Motor units –total number –activation; ... •recruitment ... Stålberg, EMG analysis 6 10 mm from end‐plates