An improved electrical impedance myography (EIM) tongue array for use in clinical trials

Abstract

Objectives Electrical impedance myography (EIM) measurements of the tongue could provide valuable information about bulbar dysfunction in amyotrophic lateral sclerosis (ALS). A prototype tongue depressor EIM array produced gag reflexes. The objectives of this study were to determine the reliability, mean phase values, and tolerability of tongue EIM measurements using a smaller electrode array. Methods Tongue EIM measurements were performed in a total of 31 healthy individuals and four neuromuscular patients with lingual abnormalities. Reliability was assessed by calculating the intraclass correlation coefficient (ICC) and percent difference in addition to performing Bland–Altman analyses. Standard descriptive statistics, including results of a Mann–Whitney test, were also determined. Results At the 50 kHz frequency, the ICCs for intra- and inter-rater reliability were 0.76 with 5.17% difference and 0.78 with 5.34% difference respectively. The mean EIM phase values of healthy participants (11.61° ± 1.00°) and patients (9.87° ± 1.28°) were significantly different (p = 0.0051). None of the participants experienced gag reflexes or discomfort. Conclusions The small tongue array provided good inter- and intra-rater reliability, could preliminarily distinguish between healthy and diseased muscle, and was well-tolerated. Significance Biomarker information about tongue health could be more comfortably obtained with a smaller EIM array.

Optimizing electrical impedance myography of the tongue in amyotrophic lateral sclerosis

“…EIM measurements of the tongue were performed using a commercially available bioimpedance system (Imp SFB7; Impedimed, Inc., Sydney Australia) connected to a small linear tongue array . Participants were asked to open the mouths.…”

“…Importantly, disease‐related changes in muscle translate into EIM phase values that are lower than those recorded from healthy muscle; qualitatively, this discrepancy has been more apparent at frequencies of between approximately 50 and 500 kH z . Accordingly, quantitative phase differences between healthy and diseased muscle may also be greater at frequencies between 50 and 500 kH z .…”

Tongue electrical impedance in amyotrophic lateral sclerosis modeled using the finite element method

“…These modeled results were then compared to previously published human data (McIlduff et al, 2015). Specifically, all human studies had been approved by Beth Israel Deaconess Medical Center’s institutional review board and informed consent had been obtained from all subjects.…”

“…Basic geometric model of tongue with electrodes on surface. B. Tongue electrode array used in the developed finite element model, using the same design as in McIlduff, et al(McIlduff, CE, Yim S, Pacheck A, Geisbush T, Mijailovic A 2015) C. Same model as in A, now with finite element mesh added.…”

Electrical Impedance Myography and Its Applications in Neuromuscular Disorders

“…This is especially important as there are few easily quantifiable assessment tools available. Recent studies have shown EIM's ability to discriminate ALSaffected tongue from healthy tongue using a simple 4electrode array constructed on a tongue depressor or similar base [80,81], using both single and multifrequency phase data. Further, a computer modeling study has shown that changes in impedance with tongue atrophy likely reflect tongue properties and are not simply an effect of decreasing tongue volume with disease progression [82].…”