title: Duration of observation required in detecting fasciculation potentials in amyotrophic lateral sclerosis using high-density surface EMG.
abstract: BACKGROUND
  High-density surface electromyography (HD-SEMG) has recently emerged as a potentially useful tool in the evaluation of amyotrophic lateral sclerosis (ALS). This study addresses a practical constraint that arises when applying HD-SEMG for supporting the diagnosis of ALS; specifically, how long the surface EMG should be recorded before one can be confident that fasciculation potentials (FPs) are absent in a muscle being tested.
  
  
  METHODS
  HD-SEMG recordings of 29 muscles from 11 ALS patients were analyzed. We used the distribution of intervals between FPs, and estimated the observation duration needed to record from one to five FPs with a probability approaching unity. Such an approach was previously tested by Mills with a concentric needle electrode.
  
  
  RESULTS
  We found that the duration of recording was up to 70 s in order to record a single FP with a probability approaching unity. Increasing recording time to 2 minutes, the probability of recording five FPs approached approximately 0.95.
  
  
  CONCLUSIONS
  HD-SEMG appears to be a suitable method for capturing FPs comparable to intramuscular needle EMG.
authors.affiliation: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, 345 E, Superior St, Suite 1406, Chicago, IL 60611, USA. p-zhou@northwestern.edu
authors.forename: Ping
authors.initials: P
authors.lastname: Zhou
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Li
authors.forename: Faezeh
authors.initials: F
authors.lastname: Jahanmiri-Nezhad
authors.forename: William Zev
authors.initials: WZ
authors.lastname: Rymer
authors.forename: Paul E
authors.initials: PE
authors.lastname: Barkhaus
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation / Q000379:methods*; D005207:Fasciculation / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D009339:Needles