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Electrical Impedance Myography (EIM)
Availability
Please visit this website for more information about the instrument: Electrical Impedance Myography
Classification
Exploratory: Facioscapulohumeral Muscular Dystrophy (FSHD) and Congenital Muscular Dystrophy (CMD)
Short Description of Instrument
Electrical impedance myography (EIM) is a non-invasive technique for the evaluation of neuromuscular disease that relies upon the application and measurement of high-frequency, low-intensity electrical current. EIM assesses disease-induced changes to muscle's normal composition and architecture, including myocyte atrophy and loss, edema, reinnervation, and the deposition of endomysial connective tissue and fat. With application of single-frequency electrical current, EIM can be used to help grade the severity of neuromuscular disease. Assessing electrical impedance across a spectrum of applied frequencies and with current flow at multiple orientations relative to the major muscle fiber direction can provide a more complete picture of muscle condition. EIM does not focus on measuring the inherent electrical activity of the tissues. Like diagnostic ultrasound, measurements are made over a small area of interest, with energy being applied to the body and the resultant surface patterns analyzed.
Comments/Special Instructions
Methodology:
 
EIM measures the impedance of skeletal muscle over a frequency range between 1 kHz and 10 MHz. The impedance is measured at each frequency by applying low-intensity electrical current (<1 mA) via surface electrodes and measuring the resulting voltage signals using a second set of surface electrodes, converting them into 2 impedance parameters, the resistance (R) and the reactance (X). The resistance and reactance can be used to calculate the phase angle.
Scoring and Psychometric Properties
Scoring: Not Applicable
 
Psychometric Properties: Not Applicable
Rationale/Justification
Strengths: Not Applicable
 
Weaknesses: Not Applicable
References
Key Reference:
 
Rutkove SB. Electrical impedance myography: Background, current state, and future directions. Muscle Nerve. 2009 Dec;40(6):936-46.
 
Additional References:
 
EIM in clinical research (General):
 
Esper GJ, Shiffman CA, Aaron R, Lee KS, Rutkove SB. Assessing neuromuscular disease with multifrequency electrical impedance myography. Muscle Nerve. 2006 Nov;34(5):595-602.
 
Rutkove SB, Sanchez B. Electrical Impedance Methods in Neuromuscular Assessment: An Overview. Cold Spring Harb Perspect Med. 2019 Oct 1;9(10):a034405
 
Sanchez B, Rutkove SB. Present Uses, Future Applications, and Technical Underpinnings of Electrical Impedance Myography. Curr Neurol Neurosci Rep. 2017 Sep 20;17(11):86.
 
Sanchez B, Rutkove SB. Electrical Impedance Myography and Its Applications in Neuromuscular Disorders. Neurotherapeutics. 2017 Jan;14(1):107-118.
 
Disease-specific recommendations:
 
EIM in ALS:
Rutkove SB, Caress JB, Cartwright MS, Burns TM, Warder J, David WS, Goyal N, Maragakis NJ, Benatar M, Sharma KR, Narayanaswami P, Raynor EM, Watson ML, Shefner JM. Electrical impedance myography correlates with standard measures of ALS severity. Muscle Nerve. 2014 Mar;49(3):441-3.
 
Rutkove SB, Caress JB, Cartwright MS, Burns TM, Warder J, David WS, Goyal N, Maragakis NJ, Clawson L, Benatar M, Usher S, Sharma KR, Gautam S, Narayanaswami P, Raynor EM, Watson ML, Shefner JM. Electrical impedance myography as a biomarker to assess ALS progression. Amyotroph Lateral Scler. 2012 Sep;13(5):439-45.
 
EIM: in CMD:
Schwartz DP, Dastgir J, Salman A, Lear B, Bönnemann CG, Lehky TJ. Electrical impedance myography discriminates congenital muscular dystrophy from controls. Muscle Nerve. 2016 Mar;53(3):402-6.
 
EIM in Duchenne Muscular Dystrophy:
Schwartz S, Geisbush TR, Mijailovic A, Pasternak A, Darras BT, Rutkove SB. Optimizing electrical impedance myography measurements by using a multifrequency ratio: a study in Duchenne muscular dystrophy. Clin Neurophysiol. 2015 Jan;126(1):202-8.
 
EIM in FSHD:
Statland JM, Heatwole C, Eichinger K, Dilek N, Martens WB, Tawil R. Electrical impedance myography in facioscapulohumeral muscular dystrophy. Muscle Nerve. 2016 Oct;54(4):696-701.
 
Mul K, Heatwole C, Eichinger K, Dilek N, Martens WB, Van Engelen BGM, Tawil R, Statland JM. Electrical impedance myography in facioscapulohumeral muscular dystrophy: A 1-year follow-up study. Muscle Nerve. 2018 Aug;58(2):213-218.
 
EIM in SMA:
Rutkove SB, Shefner JM, Gregas M, Butler H, Caracciolo J, Lin C, Fogerson PM, Mongiovi P, Darras BT. Characterizing spinal muscular atrophy with electrical impedance myography. Muscle Nerve. 2010 Dec;42(6):915-21.
 
Description of Portable EIM system:
Ogunnika OT, Rutkove SB, Ma H, Fogerson PM, Scharfstein M, Cooper RC, Dawson JL. A portable system for the assessment of neuromuscular diseases with electrical impedance myography. J Med Eng Technol. 2010 Oct-Nov;34(7-8):377-85.
 
Document last updated October 2024