Abstract
Background: Improved outcome measures are necessary to reduce sample size and increase power in amyotrophic lateral sclerosis (ALS) clinical trials. Motor unit number estimation (MUNE) is a potentially attractive tool. MUNE methods previously employed in multicenter trials exhibited excessive variability and were prone to artifact. Objective: To evaluate a modification of standard incremental MUNE in a multicenter natural history study of subjects with ALS. Methods: Fifty healthy subjects were evaluated twice and 71 subjects with ALS were studied repeatedly for up to 500 days. Side and nerve studied was based on clinical examination findings. Nerves were stimulated at 3 specified locations and 3 increments were obtained at each location. Average single motor unit action potential (SMUP) amplitude was calculated by adding the amplitude of the third increment at each location and dividing by 9; SMUP was divided into maximum CMAP amplitude to determine the MUNE. Results: Test-retest variability was 9% in normal subjects. Average MUNE for normal subjects was 225 (±87), and was 41.9 (±39) among subjects with ALS at baseline. Subjects with ALS showed clear decrements over time, with an overage rate of decline of approximately 9% per month. SMUP amplitude increased with time in a fashion consistent with the known pathophysiology of ALS. Conclusion: Multipoint incremental MUNE has a number of attributes that make it attractive as an outcome measure in ALS and other diseases characterized by motor unit loss. It can be rapidly performed on any EMG machine and has repeatability and rates of decline that favorably compare to other previously described methods.
| Original language | English |
|---|---|
| Pages (from-to) | 235-241 |
| Number of pages | 7 |
| Journal | Neurology |
| Volume | 77 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jul 19 2011 |
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ASJC Scopus subject areas
- Clinical Neurology
Cite this
Multipoint incremental motor unit number estimation as an outcome measure in ALS. / Shefner, J. M.; Watson, M. L.; Simionescu, L.; Caress, J. B.; Burns, T. M.; Maragakis, N. J.; Benatar, Michael G; David, W. S.; Sharma, Khema R; Rutkove, S. B.
In: Neurology, Vol. 77, No. 3, 19.07.2011, p. 235-241.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Multipoint incremental motor unit number estimation as an outcome measure in ALS
AU - Shefner, J. M.
AU - Watson, M. L.
AU - Simionescu, L.
AU - Caress, J. B.
AU - Burns, T. M.
AU - Maragakis, N. J.
AU - Benatar, Michael G
AU - David, W. S.
AU - Sharma, Khema R
AU - Rutkove, S. B.
PY - 2011/7/19
Y1 - 2011/7/19
N2 - Background: Improved outcome measures are necessary to reduce sample size and increase power in amyotrophic lateral sclerosis (ALS) clinical trials. Motor unit number estimation (MUNE) is a potentially attractive tool. MUNE methods previously employed in multicenter trials exhibited excessive variability and were prone to artifact. Objective: To evaluate a modification of standard incremental MUNE in a multicenter natural history study of subjects with ALS. Methods: Fifty healthy subjects were evaluated twice and 71 subjects with ALS were studied repeatedly for up to 500 days. Side and nerve studied was based on clinical examination findings. Nerves were stimulated at 3 specified locations and 3 increments were obtained at each location. Average single motor unit action potential (SMUP) amplitude was calculated by adding the amplitude of the third increment at each location and dividing by 9; SMUP was divided into maximum CMAP amplitude to determine the MUNE. Results: Test-retest variability was 9% in normal subjects. Average MUNE for normal subjects was 225 (±87), and was 41.9 (±39) among subjects with ALS at baseline. Subjects with ALS showed clear decrements over time, with an overage rate of decline of approximately 9% per month. SMUP amplitude increased with time in a fashion consistent with the known pathophysiology of ALS. Conclusion: Multipoint incremental MUNE has a number of attributes that make it attractive as an outcome measure in ALS and other diseases characterized by motor unit loss. It can be rapidly performed on any EMG machine and has repeatability and rates of decline that favorably compare to other previously described methods.
AB - Background: Improved outcome measures are necessary to reduce sample size and increase power in amyotrophic lateral sclerosis (ALS) clinical trials. Motor unit number estimation (MUNE) is a potentially attractive tool. MUNE methods previously employed in multicenter trials exhibited excessive variability and were prone to artifact. Objective: To evaluate a modification of standard incremental MUNE in a multicenter natural history study of subjects with ALS. Methods: Fifty healthy subjects were evaluated twice and 71 subjects with ALS were studied repeatedly for up to 500 days. Side and nerve studied was based on clinical examination findings. Nerves were stimulated at 3 specified locations and 3 increments were obtained at each location. Average single motor unit action potential (SMUP) amplitude was calculated by adding the amplitude of the third increment at each location and dividing by 9; SMUP was divided into maximum CMAP amplitude to determine the MUNE. Results: Test-retest variability was 9% in normal subjects. Average MUNE for normal subjects was 225 (±87), and was 41.9 (±39) among subjects with ALS at baseline. Subjects with ALS showed clear decrements over time, with an overage rate of decline of approximately 9% per month. SMUP amplitude increased with time in a fashion consistent with the known pathophysiology of ALS. Conclusion: Multipoint incremental MUNE has a number of attributes that make it attractive as an outcome measure in ALS and other diseases characterized by motor unit loss. It can be rapidly performed on any EMG machine and has repeatability and rates of decline that favorably compare to other previously described methods.
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U2 - 10.1212/WNL.0b013e318225aabf
DO - 10.1212/WNL.0b013e318225aabf
M3 - Article
VL - 77
SP - 235
EP - 241
JO - Neurology
JF - Neurology
SN - 0028-3878
IS - 3
ER -