title: Assessing neuromuscular disease with multifrequency electrical impedance myography.
abstract: Electrical impedance myography (EIM) is a noninvasive technique for neuromuscular assessment in which low-intensity alternating current is applied to a muscle and the consequent surface voltage patterns are evaluated. Previous work using a single frequency of 50 kHZ has demonstrated quantitative correlation of EIM parameters with disease status. In this investigation we examined the use of multifrequency EIM, studying a prototypical neurogenic disease (amyotrophic lateral sclerosis, ALS) and myopathic disorder (inflammatory myopathy, IM). Eleven ALS patients, 7 IM patients, and 46 normal subjects participated in the study. Although disease-specific patterns were not identified such that IM could be differentiated from ALS, impedance vs. frequency patterns for diseased subjects differed substantially from those of the age-matched normal subjects, with the greatest alterations occurring in the most severe cases. Multifrequency EIM may be well-suited to serve as an easily applied technique to assess disease severity in a variety of neuromuscular conditions.
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, TCC-810, Boston, Massachusetts 02215, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Esper
authors.forename: Carl A
authors.initials: CA
authors.lastname: Shiffman
authors.forename: Ronald
authors.initials: R
authors.lastname: Aaron
authors.forename: Kyungmouk S
authors.initials: KS
authors.lastname: Lee
authors.forename: Seward B
authors.initials: SB
authors.lastname: Rutkove
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis / Q000503:physiopathology; D003937:Diagnosis, Differential; D018450:Disease Progression; D017097:Electric Impedance; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D009220:Myositis / Q000175:diagnosis / Q000503:physiopathology; D009468:Neuromuscular Diseases / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests