Test-Retest Reliability and Agreement of Single Pulse Transcranial Magnetic Stimulation (TMS) for Measuring Activity in Motor Cortex in Patients With Acute Ischemic Stroke

BACKGROUND: Transcranial magnetic stimulation (TMS) is often used to examine neurophysiology. We aimed to investigate the inter-rater reliability and agreement of single pulse TMS in hospitalised acute ischemic stroke patients. METHODS: Thirty-one patients with first-time acute ischemic stroke (median age 72 (IQR 64-75), 35% females) underwent TMS motor threshold (MT) assessment in 4 muscles bilaterally, conducted by 1 of 2 physiotherapists. Test-retest reliability was evaluated using a two-way random effects model (2,1) absolute agreement-type Interclass Correlation Coefficient (ICC). Standard Error of Measurement (SEM) and Smallest Detectable Change (SDC) were used to evaluate agreement. RESULTS: Reliability, SEM, and SDC of TMS was found to be moderate in right opponens pollicis (0.78 [CI 95% 0.55-0.89], SEM: 4.51, SDC: 12.51), good in right vastus medialis and tibial anterior (0.88 [CI 95% 0.72-0.96], SEM: 2.89, SDC: 8.01 and 0.88 [CI 95% 0.76-0.94], SEM: 2.88, SDC: 7.98 respectively), and excellent in right and left biceps brachii (0.98 [CI 95% 0.96-0.99], SEM: 1.79 SDC: 4.96, and 0.94 [CI 95% 0.89-0.97], SEM: 2.17 SDC: 6.01), opponens pollicis (0.92 [CI 95% 0.83-0.96], SEM: 2.68 SDC: 8.26, vastus medialis (0.92 [CI 95% 0.84-0.96], SEM: 2.87 SDC: 7.95), and tibial anterior (0.93 [CI 95% 0.86-0.96], SEM: 2.51 SDC: 6.95). CONCLUSION: The TMS demonstrated moderate to excellent inter-rater reliability confirming the ability of these measures to reliably discriminate between individuals in the current study sample. Improvements of less than 4.96 to 12.51 could be a result of measurement error and may therefore not be considered a true change.