Test-Retest Reliability of Short-Interval Intracortical Inhibition Assessed by Threshold-Tracking and Automated...

Area of Science:

• Neuroscience
• Neurophysiology
• Motor Control

Background:

• Short-interval intracortical inhibition (SICI) is a key neurophysiological measure.
• Two novel protocols, TT-TMS (T-SICI) and cTMS (A-SICI), assess SICI across various interstimulus intervals (ISIs).
• Test-retest reliability is crucial for clinical translation but remains uninvestigated for these protocols.

Purpose of the Study:

• To evaluate the test-retest reliability of two novel SICI protocols (T-SICI and A-SICI).
• To assess intraobserver and interobserver reliability of these SICI protocols.
• To determine the suitability of these protocols for research and clinical applications.

Main Methods:

• 18 healthy subjects participated in four identical testing sessions over 5-7 days.
• SICI was measured using both TT-TMS (T-SICI) and cTMS (A-SICI) protocols.
• Measurements were repeated within sessions (intraobserver) and across sessions/observers (interobserver).

Main Results:

• Both T-SICI and A-SICI demonstrated moderate-to-good interday and interobserver reliability.
• Intraday reliability varied from poor-to-good for A-SICI and moderate-to-good for T-SICI.
• Individual repeatability was poor, despite comparable reliability profiles and no significant systematic bias between sessions.

Conclusions:

• The novel T-SICI and A-SICI protocols exhibit reliable and reproducible performance in research settings.
• Caution is advised when using these protocols for individual clinical decision-making due to poor repeatability.
• Further studies on patient cohorts are needed to establish clinical utility.