title: Far-field potentials in hypothenar motor unit number estimation.
abstract: BACKGROUND
  Contamination by far-field potentials (FFPs) may interfere with motor unit number estimation (MUNE) in the ulnar nerve.
  
  
  METHODS
  Surface motor unit potentials (SMUPs) from 29 spinal and bulbar muscular atrophy (SBMA) patients and 27 control subjects were classified into SMUPs from the abductor digiti minimi muscle (ADM SMUPs) or non-ADM SMUPs, based on the waveform patterns from 3-channel recordings.
  
  
  RESULTS
  The mean areas of the ADM SMUPs and non-ADM SMUPs in control subjects were 219.0 ± 131.3 and 63.7 ± 48.5 μVms, respectively. In SBMA patients they were 1988.9 ± 999.4 and 222.7 ± 125.7 μVms, respectively. The percentages of non-ADM SMUPs were 68 ± 22% in controls and 84 ± 15% in SBMA patients.
  
  
  CONCLUSIONS
  Non-ADM SMUPs generated mainly by FFPs often had a negative onset in the routine lead and were indistinguishable from ADM SMUPs. More frequent exclusion of smaller non-ADM SMUPs in controls by size criteria would reduce the diagnostic yield of MUNE.
authors: Division of Neurology, Department of Internal Medicine 3, National Defense Medical College, Namiki 3-2, Tokorozawa-shi, Saitama 3598513, Japan.
authors: Mana
authors: M
authors: Higashihara
authors: Masahiro
authors: M
authors: Sonoo
authors: Tomotaka
authors: T
authors: Yamamoto
authors: Yasuomi
authors: Y
authors: Kawamura
authors: Yu
authors: Y
authors: Nagashima
authors: Yasuo
authors: Y
authors: Terao
authors: Kenichi
authors: K
authors: Kaida
authors: Fumihiko
authors: F
authors: Kimura
authors: Yoshikazu
authors: Y
authors: Ugawa
authors: Shoji
authors: S
authors: Tsuji
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D004558:Electric Stimulation; D005260:Female; D006225:Hand / Q000294:innervation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D014459:Ulnar Nerve / Q000502:physiology*
keywords: abductor digiti minimi muscle; far-field potentials; motor unit number estimation; spinal and bulbar muscular atrophy; ulnar nerve