The original McComas technique (1971) The original McComas technique (1971) 10 S-MUAP are evoked at one single point of stimulation ALTERNATION The Multiple Point Stimulation method (Doherty & Brown, 1993) The Multiple Point Stimulation method (Doherty & Brown, 1993) 10 S-MUAP are evoked at 10 distinct stimulation points NO ALTERNATION, BUT NOT APPLICABLE TO ANY SUBJECT OR PATIENT
Incremental Stimulation (McComas 1971) - percutaneous nerve stimulation - short stimulation duration (50 µs) - weak intensity gradually increased by increments of 0.1 to 0.5 mA Individual and sequential activation of motor axons The Adapted Multiple Point Stimulation Method: AMPS (Kadrie et al. 1976; Wang & Delwaide 1995)
The mean motor unit size is estimated by the evocation of 10 S-MUAP by using incremental stimulation in distinct points of the median nerve between the wrist and elbow. The mean motor unit size is estimated by the evocation of 10 S-MUAP by using incremental stimulation in distinct points of the median nerve between the wrist and elbow. At each stimulation point, two or three S-MUAP are successively evoked and the compound motor response is selected only if S-MUAP are free of alternation. At each stimulation point, two or three S-MUAP are successively evoked and the compound motor response is selected only if S-MUAP are free of alternation.
AMPS:S-MUAP selection criteria With distinct thresholds With distinct thresholds In an all-or-nothing manner In an all-or-nothing manner Without any fractionation of the compound motor responses to successive suprathreshold stimuli Without any fractionation of the compound motor responses to successive suprathreshold stimuli In an orderly and reproducible manner In an orderly and reproducible manner S-MUAP have to be evoked
AMPS advantages AMPS minimises alternation AMPS minimises alternation Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS is non- invasive and painless AMPS is non- invasive and painless AMPS is a fast procedure AMPS is a fast procedure No specific collection system or software is required No specific collection system or software is required
AMPS minimises alternation AMPS minimises alternation Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS is non- invasive and painless AMPS is non- invasive and painless AMPS is a fast procedure AMPS is a fast procedure No specific collection system or software is required No specific collection system or software is required AMPS advantages
AMPS minimises alternation AMPS minimises alternation Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS is non- invasive and painless AMPS is non- invasive and painless AMPS is a fast procedure AMPS is a fast procedure No specific collection system or software is required No specific collection system or software is required AMPS advantages
TEST 1 TEST r = 0.83 CV = 9.5% µV.ms µV.ms r = 0.95 CV = 10.4% MU MU A. Thenar MUNEB. Average S-MUAP size
AMPS advantages r = 0.83 P < F-response method AMPS MU MU
AMPS minimises alternation AMPS minimises alternation Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS is non- invasive and painless AMPS is non- invasive and painless AMPS is a fast procedure AMPS is a fast procedure No specific collection system or software is required No specific collection system or software is required AMPS advantages
AMPS minimises alternation AMPS minimises alternation Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS is non- invasive and painless AMPS is non- invasive and painless AMPS is a fast procedure AMPS is a fast procedure No specific collection system or software is required No specific collection system or software is required AMPS advantages
AMPS minimises alternation AMPS minimises alternation Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? Incremental stimulation avoids any significant motor unit selection bias ? Erlanger and Gasser ? AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS results are reproducible (CV = 10%) and fit well with those obtained, in the same population, using an other estimation method: the F- response technique. AMPS is non- invasive and painless AMPS is non- invasive and painless AMPS is a fast procedure AMPS is a fast procedure No specific collection system or software is required No specific collection system or software is required AMPS advantages
AMPS disadvantages AMPS is not a hands - off technique AMPS is not a hands - off technique The same S-MUAP recorded twice from two different stimulation points The same S-MUAP recorded twice from two different stimulation points A subjective bias in recognition of new S-MUAP is possible A subjective bias in recognition of new S-MUAP is possible AMPS is not applicable to study proximal or deep muscles AMPS is not applicable to study proximal or deep muscles
AMPS disadvantages AMPS is not a hands - off technique AMPS is not a hands - off technique The same S-MUAP recorded twice from two different stimulation points The same S-MUAP recorded twice from two different stimulation points A subjective bias in recognition of new S-MUAP is possible A subjective bias in recognition of new S-MUAP is possible AMPS is not applicable to study proximal or deep muscles AMPS is not applicable to study proximal or deep muscles
AMPS disadvantages AMPS is not a hands - off technique AMPS is not a hands - off technique The same S-MUAP recorded twice from two different stimulation points The same S-MUAP recorded twice from two different stimulation points A subjective bias in recognition of new S-MUAP is possible A subjective bias in recognition of new S-MUAP is possible AMPS is not applicable to study proximal or deep muscles AMPS is not applicable to study proximal or deep muscles
AMPS disadvantages AMPS is not a hands - off technique AMPS is not a hands - off technique The same S-MUAP recorded twice from two different stimulation points The same S-MUAP recorded twice from two different stimulation points A subjective bias in recognition of new S-MUAP is possible A subjective bias in recognition of new S-MUAP is possible AMPS is not applicable to study proximal or deep muscles AMPS is not applicable to study proximal or deep muscles
Techniques using the incremental stimulation Techniques using the incremental stimulation Multiple Point Stimulation McComas initial technique AMPS MOTORUNITNUMBER