The Maximum-Likelihood Strategy for determining transcranial magnetic stimulation motor threshold, using Parameter Estimation by Sequential Testing is faster than conventional methods with similar precision

Alexander Mishory, Christine Molnar, Jejo Koola, Xingbao Li, F. Andrew Kozel, Hugh Myrick, Zachary Stroud, Ziad Nahas, Mark S. George

Research output: Contribution to journalArticlepeer-review

100 Scopus citations

Abstract

Background: The resting motor threshold (rMT) is the basic unit of transcranial magnetic stimulation (TMS) dosing. Traditional methods of determining rMT involve finding a threshold of either visible movement or electromyography (EMG) motor-evoked potentials, commonly approached from above and below and then averaged. This time-consuming method typically uses many TMS pulses. Mathematical programs can efficiently determine a threshold by calculating the next intensity needed based on the prior results. Within our group of experienced TMS researchers, we sought to perform an illustrative study to compare one of these programs, the Maximum-Likelihood Strategy using Parameter Estimation by Sequential Testing (MLS-PEST) approach, to a modification of the traditional International Federation of Clinical Neurophysiology (IFCN) method for determining rMT in terms of the time and pulses required and the rMT value. Methods: One subject participated in the study. Five researchers determined the same subject's rMT on 4 separate days-twice using EMG and twice using visible movement. On each visit, researchers used both the MLS-PEST and the IFCN methods, in alternating order. Results: The MLS-PEST approach was significantly faster and used fewer pulses to estimate rMT. For EMG-determined rMT, MLS-PEST and IFCN derived similar rMT, whereas for visible movement MLS-PEST rMT was higher than for IFCN. Conclusions: The MLS-PEST algorithm is a promising alternative to traditional, time-consuming methods for determining rMT. Because the EMG-PEST method is totally automated, it may prove useful in studies using rMT as a quickly changing variable, as well as in large-scale clinical trials. Further work with PEST is warranted.

Original languageEnglish (US)
Pages (from-to)160-165
Number of pages6
JournalJournal of ECT
Volume20
Issue number3
DOIs
StatePublished - 2004

Keywords

  • Algorithm
  • Excitability
  • Maximum-likelihood strategy
  • Method
  • Motor threshold
  • Parameter estimation by sequential testing
  • Transcranial magnetic stimulation

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