Нервно-мышечные болезни (Jan 2024)

Reliability of intracortical inhibiton measured using threshold tracking technique

  • I. S. Bakulin,
  • A. Kh. Zabirova,
  • A. G. Poydasheva,
  • D. O. Sinitsyn,
  • D. Yu. Lagoda,
  • N. A. Suponeva,
  • M. A. Piradov

DOI
https://doi.org/10.17650/2222-8721-2023-13-4-10-19
Journal volume & issue
Vol. 13, no. 4

Abstract

Read online

Background. Paired-pulse transcranial magnetic stimulation allows assessing intracortical inhibition. However, a high variability of motor evoked potential (MEP) amplitude is a limitation of its use. Therefore, a new threshold tracking technique became of particular interest, which is based on the measurement not of the amplitude, but of the change of test stimulus intensity required to induce a MEP of a given amplitude.Aim. The assessment of absolute and relative reliability of short-interval intracortical inhibition (SICI) using threshold tracking technique in healthy volunteers.Materials and methods. All healthy volunteers included into the study (n = 12) underwent diagnostic paired-pulse transcranial magnetic stimulation in two consecutive days. The procedure included registration of passive motor threshold; the registration of 30 MEPs with supra-threshold intensity and determination of SICI using threshold tracking technique. At the first day the procedure was performed twice (T1, T2), at the second day – once (T3). Standard error of the measurement (SEM) and SEM% were calculated to assess absolute reliability, and intra-class correlation coefficient – for the assessment of relative reliability.Results. A good or excellent relative reliability were observed for SICI averaged at intervals 1.0–3.0 ms and 1.0–7.0 ms when assessed within a day or at different days. Relative reliability of SICI at separate interstimulus intervals varied in a wide range. SEM% was more than 10 % both for averaged SICI and SICI at all interstimulus intervals. Motor threshold had excellent reliability both assessed within a day and at different days, and low SEM values (5.6 % for Т1–Т2 and 4.39 % for Т1–Т3). High SEM and SEM% were observed for average MEP amplitude, it also had a moderate relative reliability when assessed within a day and a poor one – at different days.Conclusion. Calculation of averaged SICI can be recommended in further studies because of its high reliability values.

Keywords