Parameters to quantify. shape of individual MUPs jiggle fullness recruitment (early, reduced) dynamic changes with time (fatigue) 2 normal motor units

Transcription

1 2 normal motor units STÅLBERG Reinnervated motor unit STÅLBERG STÅLBERG Muscle membrane function - spontaneous Muscle fibre characteristics; diameter MU organisation number of fibres grouping N-M transmission # motor units total activation; pattern, fullness Parameters to quantify shape of individual MUPs jiggle fullness recruitment (early, reduced) dynamic changes with time (fatigue) 1

2 A B C Electrodes CNEMG signals from 2-15 muscle fibres MU D E Central spike Slow wave components Schematic presentation of the concentric EMG MUP The simulator Parameters of a MUP Parameters used in MUP analysis T T parameter significance measurement AMPLITUDE T T phase Turn spike duration DURATION area satellite 5 ms 100 uv amplitude # fibres/0.5mm peak-peak area # fibres/2 mm within dur duration # fibres in 2.5 mm slope criteria phases temp dispersion 0-cross + 1 turns change in dir rise time closeness to fibre neg-pos peak satellites extreme delay late spike jiggle n-m transm shape stability 2

3 Normal Neuropathy MUPs in different conditions How to describe the MUP Visual assessment free run; ampl, dur, phases trigger; jiggle, extra discharges,. Automatic analysis 500 uv 10 ms Normal EMG A B C,Daube 2003 Two types of reinnervation Neuropathy Site of lesion After complete denervation After partial denervation 3

4 Schematic fig of reinnervation Satellites 2 normal motor units grouping but no extension outside borders EMG in Neuropathy A Subacute neurogenic B C D E spont (m) fib/psw CRD spont (n) neuromyot myokymia MUP ampl dur shape poly jiggle recruitment late TA/FFT neurog. fullness FD jitter,daube 2003 Inactive neurogenic spont (m) spont (n) MUP ampl dur shape jiggle recruitment late TA/FFT neurog. fullness FD jitter 4

5 EMG in A B spont (m) fib/psw myotonic CRD spont (n) MUP ampl dur shape poly jiggle recruitment early TA/FFT myopathic fullness normal FD jitter normal,daube 2003 Central weakness spont (m) spont (n) MUP normal shape normal jiggle normal recruitment irregular TA/FFT fullness FD normal jitter Decomposition; techniques to decompose a mixed signal into its constituents Multi-MUP, result This example: Multi MUP analysis 5

6 Parameters for durationmeasurement Nomenclature interference pattern summation pattern recruitment pattern pattern at full effort Interference pattern 6

7 Onset frequency= freq of a MUP when recruited Recruitment frequency= freq. of 1 st MU when 2 nd is recruited neuropathy myopathies Recruitment ratio (slight contraction) = # discharges/# active MUs normal Hz Onset freq = 6 Hz Recruitment freq = 9Hz Recruit rat. = 20/5 = 5 myopathy neurogenic Hz Onset= 7 Hz Recruit rat. = 10/3= Hz Onset= 12 Hz Recruit rat = 12/3=4 EMG - interference pattern visual inspection (ampl, fullness) spectral analysis broad band filter analysis turns/amplitude analysis envelope, NSS, activity FFT Normal Neuropathy 1 mv 1 s 7

8 Envelope amplitude of IP IP envelope amplitudes, unpublished.data Visual: keep standard gain and sweep speed: 0,5mV msec/div Measure: eyeballing KP, T/A or Envelope Biceps <1400uV IOD <4000 APB <2800 TA <4300 Vast lat <2800 Fullness of IP Fullness of IP No gaps! Full pattern Gaps in the pattern! Reduced IP Interference pattern analysis in normal, neuropathic and myopathic conditions Summary MUP analysis: superior for shape description unique for MUP instability (jiggle) time consuming if not automatized IP analysis: some methods reflect shape parameters unique information about fullness unique information about high threshold motor units automatic methods necessary for quantitation 8

9 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 9