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Parameters to quantify
2 normal motor units STÅLBERG Myopathy Reinnervated motor unit STÅLBERG STÅLBERG Parameters to quantify • Muscle membrane function - spontaneous • Muscle fibre characteristics; diameter • MU organisation – number of fibres – grouping • N-M transmission • # motor units – total – activation; pattern, fullness • shape of individual MUPs • • • • jiggle fullness recruitment (early, reduced) dynamic changes with time (fatigue) Stålberg Stålberg 1 Electrodes A B C MU D E Stålberg Visual scoring Spontaneous activity from the muscle Spontaneous activity in normal • • • • insertional activity end-plate noise ”nerve spikes” positive wave at end-plate zone • • • • • 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 scoring Spontaneous activity in myopathy Muscular dystrophies Spontaneous activity from the nerve • • • • • FINDING neuromyotonic discharges myokymic discharges muscle cramps fasciculations neurogenic extra discharges Myositis, IBM Debrancher Glycogenosis Acid Maltase Deficiency Fib, PSW ? Yes Hyperkalemic per paralysis Myotonic conditions LGMD 1A MEASURE AS • #/ 10 recording sites • or +, ++, +++, ++++ – few (per time unit) – moderate – abundant • indicate Myotonic Disch. ? Nemaline myopathy No Myotubular myopathy Mitochondrial myopathy Carnitine Deficency CRD ? No Hypothyroid myopathy Rhabdomyolysis Toxic - Chloroquine - Alcoholic - Statins - Colchicine – spontaneous or – after provocation Courtesy R.Liguori, modified 2 Spontaneous activity in myopathy Spontaneous activity in myopathy Muscular dystrophies Muscular dystrophies Myositis, IBM Myositis, IBM Debrancher Glycogenosis Debrancher Glycogenosis Acid Maltase Deficiency Fib, PSW ? Yes Acid Maltase Deficiency Fib, PSW ? Hyperkalemic per paralysis Yes Myotonic conditions Myotonic conditions LGMD 1A Myotonic Disch. ? CRD ? LGMD 1A Nemaline myopathy Yes No Myotonic Disch. ? Myotubular myopathy Nemaline myopathy Yes Mitochondrial myopathy Carnitine Deficency Carnitine Deficency Hypothyroid myopathy CRD ? Rhabdomyolysis Yes - Chloroquine - Alcoholic - Statins - Colchicine - Colchicine Spontaneous activity in myopathy Muscular dystrophies Muscular dystrophies Myositis, IBM Myositis, IBM Debrancher Glycogenosis Debrancher Glycogenosis Acid Maltase Deficiency Fib, PSW ? Hyperkalemic per paralysis No Myotonic conditions LGMD 1A LGMD 1A Myotonic Disch. ? Myotubular myopathy Nemaline myopathy Yes Carnitine Deficency Hypothyroid myopathy CRD ? Rhabdomyolysis Toxic Myotubular myopathy Mitochondrial myopathy Carnitine Deficency Yes Hyperkalemic per paralysis Myotonic conditions Mitochondrial myopathy CRD ? - Chloroquine - Statins Nemaline myopathy No Rhabdomyolysis Toxic Acid Maltase Deficiency Myotonic Disch. ? Hypothyroid myopathy - Alcoholic Spontaneous activity in myopathy Yes Myotubular myopathy Mitochondrial myopathy Toxic Fib, PSW ? Hyperkalemic per paralysis - Chloroquine No Hypothyroid myopathy Rhabdomyolysis Toxic - Chloroquine - Alcoholic - Alcoholic - Statins - Statins - Colchicine - Colchicine CNEMG signals from 2 - 15 muscle fibres Schematic presentation of the concentric EMG MUP Central spike Slow wave components Stålberg Stålberg 3 The simulator Parameters of a MUP T T T T area phase AMPLITUDE satellite Turn spike duration DURATION 100 uV 5 ms www.keypointclub.com Parameters used in MUP analysis parameter significance measurement • • • • • • • • # fibres/0.5mm # fibres/2 mm # fibres in 2.5 mm temp dispersion “ closeness to fibre extreme delay n-m transm peak-peak amplitude area duration phases turns rise time satellites jiggle slope criteria 0-cross + 1 change in dir neg-pos peak late spike shape stability Stålberg MUPs in different conditions How to describe the MUP Normal Visual assessment free run; ampl, dur, phases trigger; jiggle, extra discharges, …. Automatic analysis Neuropathy Myopathy 500 uV 10 ms Stålberg 4 Normal EMG A B C Stålberg,Daube 2003 Two types of reinnervation Neuropathy Site of lesion After complete denervation After partial denervation Stålberg Schematic fig of reinnervation 2 normal motor units grouping but no extension outside borders Satellites Stålberg Stålberg 5 EMG in Neuropathy A Subacute neurogenic B • • • • • • • • • • C D spont (m) fib/psw CRD spont (n) neuromyot myokymia MUP ampl dur shape poly jiggle recruitment late TA/FFT neurog. fullness FD jitter E Stålberg,Daube 2003 Stålberg Inactive neurogenic • • • • • • • • • • spont (m) spont (n) MUP shape jiggle recruitment TA/FFT fullness FD jitter ampl Myopathy dur late neurog. Stålberg Myopathy EMG in Myopathy • spont (m) • spont (n) • MUP A • • • • • • • B fib/psw shape jiggle recruitment TA/FFT fullness normal FD jitter normal myotonic CRD ampl dur poly early myopathic Stålberg,Daube 2003 Stålberg 6 Parameters that can be assessed visually/manually Central weakness • • • • • • • • • • spont (m) spont (n) MUP shape jiggle recruitment TA/FFT fullness FD jitter normal normal normal irregular normal parameter significance measurement • • • • • • • • • • • # fibers/0.5mm # fibers/2 mm # fibers in 2.5 mm # close fibre MU size temp dispersion “ “ closeness to fibre extreme delay n-m transm peak-peak within dur slope criteria area/ampl normalized thickness 0-cross + 1 change in dir length/ampl neg-pos peak late spike shape stability Amplitude area Duration Thickness Size index Phases Turns Irregularity Rise time Satellites Jiggle Stålberg Stålberg Decomposition; techniques to decompose a mixed signal into its constituents This example: Multi MUP analysis Stålberg Multi-MUP, result Jiggle in normal and abnormal MUPs Normal ALS Stålberg 7 So, shall I use all these parameters?? Amplitude (Tib.ant.) polymyositis Which one is best? 0.87 -2SD Let us look at the diagnostic power of a few parameters +2SD SD ALS ,13 SD Stålberg,Erdem unpublished Area Duration polymyositis polymyositis 0.88 .36 ALS ALS 0,85 .46 Stålberg,Erdem unpublished Thickness Stålberg,Erdem unpublished Size index polymyositis polymyositis ALS ALS Stålberg,Erdem unpublished Stålberg,Erdem unpublished 8 Reference values necessary to separate abnormal from normal Combination of abnormally small and large MUPs (Hereditary distal myopathy) This is a crucial point in quantitative EMG analysis • • • • mean, SD (# of SDs = Z-score) median, percentiles outliers combine different data (multivariate analysis, index) outlier A few examples Combination of abnormally small and large MUPs (Hereditary distal myopathy) Lat vastus m 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 outliers • reliable results also from less experienced EMGers • good during training Lat vastus m 9
