Statistical MUNE: a comparison of two methods of setting recording windows in healthy subjects and ALS patients.
OBJECTIVE
To address the issue as to how best to perform statistical MUNE, we applied two different approaches and compared results in healthy subjects and ALS patients.


METHODS
Twelve normal subjects (women 8, mean age 52years) and 11 ALS patients (women 4, mean age 54years) underwent two consecutive MUNE studies, which differed in terms of setting and modifying the recording window. These are referred to as the 'expansion' and 'narrowing' methods, respectively. Size-weighted average (Av) SMUP and MUNE values were obtained using the two methods, and compared in control and patient groups.


RESULTS
Expansion method-derived Av SMUP sizes and MUNE values differed only slightly from those obtained using the narrowing method in healthy subjects, whereas the narrowing method resulted in significantly larger Av SMUP sizes and smaller MUNE values than the expansion method in ALS patients (Wilcoxon signed ranks test, p=0.003). The sizes of tested areas (mean+/-SD) were significantly larger for the narrowing method than the expansion method in both subject groups with much greater difference in ALS patients; 9.6+/-3.1% vs. 7.9+/-1.7% in healthy subjects and 16.1+/-5.1% vs. 11.2+/-3.0% in ALS patients (Student t-test, p<0.01).


CONCLUSIONS
The present study shows, unlike that found in normal subjects, that the results of statistical MUNE in ALS patients are heavily dependent on the approach used to set and modify recording windows.


CONCLUSIONS
The expansion method using a 10%-sized window is likely to suffer from systemic errors due to the ceiling effect and the sampling of artifactually small motor units in ALS patients. The authors recommend that the narrowing method be considered as an alternative that avoids these problems.
Hong
Yoon-Ho
YH
Department of Neurology, Seoul National University College of Medicine, Boramae Hospital, Seoul, Republic of Korea.
Sung
Jung-Joon
JJ
Park
Kyung Seok
KS
Kwon
Ohyun
O
Min
Ju-Hong
JH
Lee
Kwang-Woo
KW
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000503:physiopathology; D003625:Data Collection; D003627:Data Interpretation, Statistical; D004568:Electrodiagnosis / Q000379:methods*; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D009469:Neuromuscular Junction / Q000502:physiology*; D011237:Predictive Value of Tests; D012016:Reference Values; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted