Electrical impedance myography as a biomarker of inclusion body myositis: A cross-sectional study

Clin Neurophysiol. 2020 Feb;131(2):368-371. doi: 10.1016/j.clinph.2019.10.030. Epub 2019 Dec 6.

Abstract

Objective: To assess the value of electrical impedance myography (EIM) in inclusion body myositis (IBM).

Methods: Patients with clinically defined IBM and healthy controls (HC) of similar age group were recruited. Each participant underwent manual muscle testing (MMT), 6-min walk test (6MWT), handgrip dynamometry, and IBM-functional rating scale assessment (IBM-FRS). EIM measurements were obtained from bilateral deltoid, biceps, forearm-flexors, quadriceps, tibialis anterior, and medial gastrocnemius.

Results: Fourteen IBM patients and 12 HCs with mean age 68.6 ± 6 and 67.4 ± 5.4 years were included in the final analysis. Averaged phase value at 50 kHz (EIM50) and ratio of phase value at 50 kHz/200 kHz (EIMPR) from six-muscles were significantly lower in IBM patients when compared to HC (5.23 ± 1.34 vs 7.88 ± 1.9, p-value 0.002, and 0.55 ± 0.09 vs. 0.68 ± 0.09, p-value 0.004, respectively). A strong correlation was noted between IBM-FRS, 6MWT, disease-duration and the averaged value of EIM50 and EIMPR in the IBM patients (Spearman |rho|>0.7, p-values < 0.01).

Conclusions: EIM can differentiate between IBM patients and HCs and EIM parameters correlate with clinical outcome measures.

Significance: EIM may be a potential objective biomarker for IBM. A longitudinal validation study is warranted.

Keywords: Biomarker; EIM; IBM; Outcome measures.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Electric Impedance
  • Female
  • Hand Strength
  • Humans
  • Male
  • Middle Aged
  • Muscle, Skeletal / physiopathology
  • Myography / methods*
  • Myography / standards
  • Myositis, Inclusion Body / diagnosis
  • Myositis, Inclusion Body / physiopathology*
  • Sensitivity and Specificity