Duration of observation required in detecting fasciculation potentials in amyotrophic lateral sclerosis using high-density surface EMG
1 Sensory Motor Performance Program, Rehabilitation Institute of Chicago, 345 E. Superior St, Suite 1406, Chicago, IL 60611, USA
2 Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, USA
3 Institute of Biomedical Engineering, University of Science and Technology of China, Hefei, China
4 Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
5 Department of Neurology, Medical College of Wisconsin and the Milwaukee Veterans Administration Medical Center, Milwaukee, WI, USA
Journal of NeuroEngineering and Rehabilitation 2012, 9:78 doi:10.1186/1743-0003-9-78Published: 10 October 2012
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.
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.
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.
HD-SEMG appears to be a suitable method for capturing FPs comparable to intramuscular needle EMG.