title: "Clustering Index method": a new technique for differentiation between neurogenic and myopathic changes using surface EMG.
abstract: OBJECTIVE
  To establish a non-invasive and quantitative analysis method using single-channel surface EMG (SEMG) for diagnosing neurogenic and myopathic changes.
  
  
  METHODS
  The subjects consisted of 66 healthy controls, 12 patients with neurogenic diseases, and 18 patients with myopathic diseases. The tibialis anterior muscle was examined using a belly to the adjacent bone lead. From each subject, 20-40 signals of 1 s length were collected of various strengths. A new parameter, the "Clustering Index (CI)", was developed to quantify the uneven distribution of the SEMG signal, and was plotted against the SEMG area. The results were expressed as the Z-score of each subject calculated using linear regression from the normative data.
  
  
  RESULTS
  When ±2.5 was used as the cut-off value of the Z-score, the specificity was 95%, whereas the sensitivity was 92% (11/12) and 61% (11/18) for the neurogenic and myopathic patients, respectively. There was no overlap of the Z-score values between the neurogenic and myopathic groups.
  
  
  CONCLUSIONS
  The CI method achieved a reasonably high diagnostic yield in detecting neurogenic or myopathic changes.
  
  
  CONCLUSIONS
  This is a new simple and quantitative analysis method using SEMG with good reproducibility, and is promising as a non-invasive complement to needle EMG.
authors.affiliation: Department of Neurology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Uesugi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sonoo
authors.forename: Erik
authors.initials: E
authors.lastname: Stålberg
authors.forename: Kohji
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Mana
authors.initials: M
authors.lastname: Higashihara
authors.forename: Hideharu
authors.initials: H
authors.lastname: Murashima
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ugawa
authors.forename: Yu
authors.initials: Y
authors.lastname: Nagashima
authors.forename: Teruo
authors.initials: T
authors.lastname: Shimizu
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Saito
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kanazawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009135:Muscular Diseases / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results