Annals of Biomedical Engineering

, Volume 45, Issue 6, pp 1572–1580 | Cite as

Handheld Electrical Impedance Myography Probe for Assessing Carpal Tunnel Syndrome

  • Zhao Li
  • Lingfen Chen
  • Yu Zhu
  • Qingquan Wei
  • Wenwen Liu
  • Dong Tian
  • Yude Yu


Electrical impedance myography (EIM) is a novel, noninvasive, and painless technique for quantitatively assessing muscle health as well as disease status and progression. The preparatory work for commercial adhesive electrodes used in previous EIM measurements is tedious, as the electrodes need to be cut, repeatedly applied, and removed. Moreover, the electrode distances need to be measured many times. To overcome these problems, we developed a convenient and practical handheld EIM probe for assessing carpal tunnel syndrome (CTS) in the small hand muscles. To reduce the electrode–skin contact impedance (ESCI), the micropillared and microholed stainless steel electrodes (SSEs) contained in the probe were fabricated using a laser processing technique. When covered with saline, these electrodes showed lower ESCIs than a smooth SSE and Ag/AgCl electrode. The probe was shown to have excellent test–retest reproducibility in both healthy subjects and CTS patients, with intraclass correlation coefficients exceeding 0.975. The reactance and phase values of the abductor pollicis brevis (affected muscle) for CTS patients were consistently lower than those for healthy subjects, with a 50-kHz difference of 37.1% (p < 0.001) and 31.0% (p < 0.001), respectively. Further, no significant differences were detected in the case of the abductor digiti minimi (unaffected muscle). These results indicate that EIM has considerable potential for CTS assessment and hence merits further investigation.


Muscle impedance Microstructures Handheld probe Neuromuscular assessment 



Abductor digiti minimi


Amyotrophic lateral sclerosis


Abductor pollicis brevis


Compound motor action potential


Carpal tunnel syndrome


Distal motor latency


Electrical impedance myography


Electrode-skin contact impedance


Intraclass correlation coefficient


Sensory nerve action potential


Sensory nerve conduction velocity


Stainless steel electrode



This study was supported by the National Natural Science Foundation of China (Grant No. 61376072, 61334008). The authors acknowledge the support of the Department of Hand Surgery, HuaShan Hospital of Fudan University.


  1. 1.
    Ching, C. T., et al. Characterization of the muscle electrical properties in low back pain patients by electrical impedance myography. PLoS ONE 8(4):e61639, 2013.CrossRefPubMedPubMedCentralGoogle Scholar
  2. 2.
    Garmirian, L. P., et al. Discriminating neurogenic from myopathic disease via measurement of muscle anisotropy. Muscle Nerve 39:16–24, 2009.CrossRefPubMedPubMedCentralGoogle Scholar
  3. 3.
    Geisbush, T. R., et al. Inter-session reliability of electrical impedance myography in children in a clinical trial setting. Clin. Neurophysiol. 126(9):1790–1796, 2015.CrossRefPubMedGoogle Scholar
  4. 4.
    Ibrahim, I., et al. Carpal tunnel syndrome: a review of the recent literature. Open Orthop. J. 6:69–76, 2012.CrossRefPubMedPubMedCentralGoogle Scholar
  5. 5.
    Kalvøy, H., et al. Electrical impedance of stainless steel needle electrodes. Ann. Biomed. Eng. 38(7):2371–2382, 2010.CrossRefPubMedGoogle Scholar
  6. 6.
    Kautek, W., et al. Femtosecond-pulse laser ablation of metallic, semiconducting, ceramic, and biological materials. SPIE Proc. 2207:600–611, 1994.CrossRefGoogle Scholar
  7. 7.
    Khalil, S. F., et al. The theory and fundamentals of bioimpedance analysis in clinical status monitoring and diagnosis of diseases. Sensors (Basel) 14(6):10895–10928, 2014.CrossRefGoogle Scholar
  8. 8.
    Li, J., et al. A comparison of three electrophysiological methods for the assessment of disease status in a mild spinal muscular atrophy mouse model. PLoS ONE 9(10):e111428, 2014.CrossRefPubMedPubMedCentralGoogle Scholar
  9. 9.
    Li, Z., et al. Microneedle electrode array for electrical impedance myography to characterize neurogenic myopathy. Ann. Biomed. Eng. 44(5):1566–1575, 2016.CrossRefPubMedGoogle Scholar
  10. 10.
    Luft, A., et al. A study of thermal and mechanical effects on materials induced by pulsed laser drilling. Appl. Phys. A 63:93–101, 1996.CrossRefGoogle Scholar
  11. 11.
    McAdams, E. T., et al. Factors affecting electrode-gel-skin interface impedance in electrical impedance tomography. Med. Biol. Eng. Comput. 34:397–408, 1996.CrossRefPubMedGoogle Scholar
  12. 12.
    McIlduff, C., et al. An improved electrical impedance myography (EIM) tongue array for use in clinical trials. Clin. Neurophysiol. 127(1):932–935, 2016.CrossRefPubMedGoogle Scholar
  13. 13.
    McIlduff, C. E., et al. Optimizing electrical impedance myography of the tongue in ALS. Muscle Nerve 2016. doi: 10.1002/mus.25375.PubMedGoogle Scholar
  14. 14.
    Middleton, S. D., et al. Carpal tunnel syndrome. BMJ 349:g6437, 2014.CrossRefPubMedGoogle Scholar
  15. 15.
    Narayanaswami, P., et al. Utilizing a handheld electrode array for localized muscle impedance measurements. Muscle Nerve 46(2):257–263, 2012.CrossRefPubMedPubMedCentralGoogle Scholar
  16. 16.
    Perry, M. D., et al. Ultrashort-pulse laser machining of dielectric materials. J. Appl. Phys. 85(9):6803–6810, 1999.CrossRefGoogle Scholar
  17. 17.
    Rafael, R., et al. Femtosecond laser micromachining in transparent materials. Nat. Photon. 2:219–225, 2008.CrossRefGoogle Scholar
  18. 18.
    Riccò, M., et al. Personal risk factors for carpal tunnel syndrome in female visual display unit workers. Int. J. Occup. Med. Environ. Health 29(6):927–936, 2016.CrossRefPubMedGoogle Scholar
  19. 19.
    Rizvi, N. H., et al. Femtosecond laser micromachining: current status and applications. RIKEN Rev. 50:107–112, 2003.Google Scholar
  20. 20.
    Rutkove, S. B. Electrical impedance myography: background, current state, and future directions. Muscle Nerve 40(6):936–946, 2009.CrossRefPubMedPubMedCentralGoogle Scholar
  21. 21.
    Rutkove, S. B., et al. Localized bioimpedance analysis in the evaluation of neuromuscular disease. Muscle Nerve 25:390–397, 2002.CrossRefPubMedGoogle Scholar
  22. 22.
    Rutkove, S. B., et al. Characterizing spinal muscular atrophy with electrical impedance myography. Muscle Nerve 42(6):915–921, 2010.CrossRefPubMedGoogle Scholar
  23. 23.
    Rutkove, S. B., et al. Electrical impedance myography as a biomarker to assess ALS progression. Amyotroph. Lateral Scler. 13(5):439–445, 2012.CrossRefPubMedPubMedCentralGoogle Scholar
  24. 24.
    Rutkove, S. B., et al. Electrical impedance myography in spinal muscular atrophy: a longitudinal study. Muscle Nerve 45(5):642–647, 2012.CrossRefPubMedGoogle Scholar
  25. 25.
    Rutkove, S. B., et al. Electrical impedance myography correlates with standard measures of ALS severity. Muscle Nerve 49(3):441–443, 2014.CrossRefPubMedGoogle Scholar
  26. 26.
    Rutkove, S. B., et al. Cross-sectional evaluation of electrical impedance myography and quantitative ultrasound for the assessment of Duchenne muscular dystrophy in a clinical trial setting. Pediatr. Neurol. 51(1):88–92, 2014.CrossRefPubMedPubMedCentralGoogle Scholar
  27. 27.
    Sanchez, B., et al. Evaluation of Electrical Impedance as a Biomarker of Myostatin Inhibition in Wild Type and Muscular Dystrophy Mice. PLoS ONE 10(10):e0140521, 2015.CrossRefPubMedPubMedCentralGoogle Scholar
  28. 28.
    Schwartz, S., et al. Optimizing electrical impedance myography measurements by using a multifrequency ratio: a study in Duchenne muscular dystrophy. Clin. Neurophysiol. 126(1):202–208, 2015.CrossRefPubMedGoogle Scholar
  29. 29.
    Shellikeri, S., et al. Electrical impedance myography in the evaluation of the tongue musculature in amyotrophic lateral sclerosis. Muscle Nerve 52(4):584–591, 2015.CrossRefPubMedPubMedCentralGoogle Scholar
  30. 30.
    Spieker, A. J., et al. Electrical impedance myography in the diagnosis of radiculopathy. Muscle Nerve 48(5):800–805, 2013.CrossRefPubMedGoogle Scholar
  31. 31.
    Statland, J. M., et al. Electrical impedance myography in facioscapulohumeral muscular dystrophy. Muscle Nerve 54(4):696–701, 2016.CrossRefPubMedGoogle Scholar
  32. 32.
    Sugioka, K., et al. Femtosecond laser 3D micromachining: a powerful tool for the fabrication of microfluidic, optofluidic, and electrofluidic devices based on glass. Lab Chip 14(18):3447–3458, 2014.CrossRefPubMedGoogle Scholar
  33. 33.
    Sung, M., et al. The effect of subcutaneous fat on electrical impedance myography when using a handheld electrode array: the case for measuring reactance. Clin. Neurophysiol. 124(2):400–404, 2013.CrossRefPubMedGoogle Scholar
  34. 34.
    van Suchtelen, M., et al. Progression of carpal tunnel syndrome according to electrodiagnostic testing in nonoperatively treated patients. Arch. Bone Joint. Surg. 2:185–191, 2014.PubMedPubMedCentralGoogle Scholar
  35. 35.
    Wang, L. L., et al. Electrical impedance myography for monitoring motor neuron loss in the SOD1 G93A amyotrophic lateral sclerosis rat. Clin. Neurophysiol. 122(12):2505–2511, 2011.CrossRefPubMedPubMedCentralGoogle Scholar
  36. 36.
    Wu, J. S., et al. Assessment of aged mdx mice by electrical impedance myography and magnetic resonance imaging. Muscle Nerve 52(4):598–604, 2015.CrossRefPubMedGoogle Scholar
  37. 37.
    Yin, Y., et al. Comparison of three kinds of electrode-skin interfaces for electrical impedance scanning. Ann. Biomed. Eng. 38(6):2032–2039, 2010.CrossRefPubMedGoogle Scholar
  38. 38.
    Zaidman, C. M., et al. Electrical impedance myography in Duchenne muscular dystrophy and healthy controls: a multicenter study of reliability and validity. Muscle Nerve 52(4):592–597, 2015.CrossRefPubMedGoogle Scholar

Copyright information

© Biomedical Engineering Society 2017

Authors and Affiliations

  1. 1.State Key Laboratory on Integrated Optoelectronics, Institute of SemiconductorsChinese Academy of SciencesBeijingChina
  2. 2.Department of Hand SurgeryHuashan Hospital of Fudan UniversityShanghaiChina
  3. 3.Department of Physical Medicine and Rehabilitation, Upstate Medical University at SyracuseState University of New YorkSyracuseUSA
  4. 4.College of Materials Science and Opto-Electronic TechnologyUniversity of Chinese Academy of SciencesBeijingChina

Personalised recommendations