Faculty Collaboration Database

Automatic analysis of the electromyographic interference pattern using the turns: amplitude ratio. Electroencephalogr Clin Neurophysiol 1988 Dec;70(6):534-40

Date

12/01/1988

Pubmed ID

2461287

DOI

10.1016/0013-4694(88)90151-4

Scopus ID

2-s2.0-0023816212 (requires institutional sign-in at Scopus site)   24 Citations

Abstract

This study was performed to compare different techniques of analyzing the electromyographic interference pattern (IP). Recordings were made from the biceps muscle with a concentric needle electrode at different sites and at different constant levels of voluntary contraction. The number of turns per second (NT), the mean amplitude change between successive turns (MA) and NT:MA ratio were determined for epochs of 1 sec duration. Normal limits of individual epoch NT:MA ratios and the mean value of NT:MA ratio obtained from all epochs in each muscle were determined. The mean NT:MA ratio was less in normal males than in females. IP recordings were made in the biceps muscle of 69 patients with neuropathy and 54 patients with myopathy, though this muscle was not necessarily affected by the disease in all patients. The IP was abnormal by visual inspection in 82% of patients compared to 61% based on NT:MA ratio and 74% using a technique that automatically quantitates some features of the IP that are assessed subjectively by an electromyographer. All techniques demonstrated IP abnormalities in more than 80% of the muscles that were moderately to severely weak. Though measuring the NT:MA ratio without monitoring the force of contraction is not as sensitive as other IP analysis techniques, it may be useful in quantitating abnormalities when other techniques are not available.

Author List

Gilchrist JM, Nandedkar SD, Stewart CS, Massey JM, Sanders DB, Barkhaus PE

Author

Paul E. Barkhaus MD Professor in the Neurology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adult
Diagnosis, Computer-Assisted
Electricity
Electromyography
Female
Humans
Male
Middle Aged
Muscles
Muscular Diseases
Nervous System Diseases
Reference Values