Method to assess the mismatch between the measured and nominal parameters of transcranial magnetic stimulation devices

Research output: Contribution to journalArticleScientificpeer-review


  • Leonardo Rakauskas Zacharias
  • André Salles Cunha Peres
  • Victor Hugo Souza
  • Adriana Bastos Conforto
  • Oswaldo Baffa

Research units

  • Universidade de São Paulo
  • Instituto Santos Dumont
  • Universidade Federal do Rio Grande do Norte
  • Hospital Israelita Albert Einstein


Background: Small variations in TMS parameters, such as pulse frequency and amplitude may elicit distinct neurophysiological responses. Assessing the mismatch between nominal and experimental parameters of TMS stimulators is essential for safe application and comparisons of results across studies. New method: A search coil was used to assess exactness and precision errors of amplitude and timing parameters such as interstimulus interval, the period of pulse repetition, and intertrain interval of TMS devices. The method was validated using simulated pulses and applied to six commercial stimulators in single-pulse (spTMS), paired-pulse (ppTMS), and repetitive (rTMS) protocols, working at several combinations of intensities and frequencies. Results: In a simulated signal, the maximum exactness error was 1.7% for spTMS and the maximum precision error 1.9% for ppTMS. Three out of six TMS commercial devices showed exactness and precision errors in spTMS amplitude higher than 5%. Moreover, two devices showed amplitude exactness errors higher than 5% in rTMS with parameters suggested by the manufactures. Comparison with existing methods: Currently available tools allow characterization of induced electric field intensity and focality, and pulse waveforms of a single TMS pulse. Our method assesses the mismatch between nominal and experimental values in spTMS, ppTMS and rTMS protocols through the exactness and precision errors of amplitude and timing parameters. Conclusion: This study highlights the importance of evaluating the physical characteristics of TMS devices and protocols, and provides a method for on-site quality assessment of multiple stimulation protocols in clinical and research environments.


Original languageEnglish
Pages (from-to)83-87
Number of pages5
JournalJournal of Neuroscience Methods
Publication statusPublished - 1 Jul 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • Accuracy, Exactness, Precision, Quality assessment, Reliability, rTMS, TMS

ID: 33694163