Table 2.
TMS experiments description
| Study | Area of interest | Type of coil | Muscle Evaluated | Outcome measure | Parameters | Risk of Bias score |
|---|---|---|---|---|---|---|
| Bement (2014) | Motor cortex (M1) | Round coil | Brachioradialis muscle | Motor evoked potential (MEP) amplitude | They determined the MEP threshold by applying a single pulse of maximum stimulator output in M1 to generate an MEP in the muscle evaluated - at an intensity of 40%–70%- and used the intensity of 120% of this threshold in each session. | 17 |
| Carinal (2019) | M1 | Figure-eight coils | First dorsal interosseous (FDI) | Short intracortical inhibition (SICI), intracortical facilitation (ICF), MEP and cortical silent period (CSP) | The motor threshold (MT) was assessed as the lowest stimuli to induce 50% of the evoked potential in the resting FDI. They used a single-pulse TMS protocol with 130% of the intensity of the MT applied to record ten MEP. The CSP was measured during muscle activity - twenty percent of maximal force). The authors also used an interstimulus interval of 2 and 12 ms and paired-pulse to measure ICF and SICI. | 15 |
| Caumo (2016) | M1 | Figure-eight coils | FDI | Short ICF, SICI, MEP and CSP. | The authors determined the resting MT
(RMT) using 50% of ten consecutive trials MEPs and then recorded another ten MEPs using 130% intensity of the individual RMT. The CSPs were measured during muscle activity assessed on a dynamometer set to approximately 20% of the maximal force. Also, the authors used paired pulse to measure ICI and SICI, with an interstimulus interval of 2 and 12 ms, respectively. |
14 |
| Ciampide Andrade (2017) | M1 | Circular shaped coil | Thenar eminences | Rest MT (RMT), MEP, Short intracortical Inhibition (SICI) and ICF |
SICI and ICF were measured at an interstimulus interval of 2 and 4 ms and at 10 and 15 ms, respectively. The authors didn’t describe how they assess the RMT and MEP. | 12 |
| Kaziyama (2020) | M1 | Circular coil | FDI | RMT, MEPs, SICI, and ICF | The RMT was assessed as the lower intensity to elicit an MEP of at least 50 μV in 50% of trials. They investigate intracortical modulation using paired pulse; interstimulus intervals (ISIs) of 2 and 4 ms were used to measure SICI, while ISIs of 10 and 15 ms were used to assess ICF. | 15 |
| Kukseymen (2020) | M1 | figure-of-eight coil | FDI | RMT, MEPs, SICI, and ICF | The authors assessed the RMT as the lower intensity to elicit an MEP of at least 100 μV in 3/5 of trials in the relaxed muscle. The MEP was assessed as 120% of the MT intensity and the ISI for SICI and ICF was 2 ms and 10 ms, using the paired pulse protocol. | 15 |
| Deitos (2018) | M1 | Figure-eigh coil | FDI | CSP, SICI, RMT and MEP | The RMT was defined as the lower intensity to elicit an MEP of at least 50 μV in 10 consecutive trials. The MEP was recorded as 130% of the MT intensity, and the CSPs were assessed with a dynamometer as 20% of the maximal force during the muscle contraction and recorded using an intensity of 130% of the RMT. SICI and ICF were measured using a paired-pulse TMS protocol, using an ISI of 2 and 4 ms for the SICI and 9 and 12 ms for the ICF. | 12 |
| Mhala (2011) | M1 | figure-8-shaped coil | First interosseous muscle (FDI) | MEP, RMT, SICI and ICF | The authors tested the RMT as the minimal intensity to elicit an MEP of at least 50 μV in 50% of trials. Using a paired-pulse protocol, they recorded the intensity of the MEP test stimuli as 120% of the RMT. They also used ISIs of 2 and 4 ms for SICI and 10 and 15 ms for ICF. | 12 |
| Mendonca (2016) | M1 | Figure-of-eight coil | Adductor muscle of the thumb | MT, MEP, intracortical inhibition, and ICF | RMT was determined as the lower intensity to generate an MEP of at least 50 mV in 10 trials; to determine the MEP, they used 120% of the resting MT. The inter stimulus interval was 10 ms for ICF and 2 ms for intracortical inhibition, using the paired-pulse technic. | 14 |
| Mhala (2010) | M1 | Figure-of-eight-shaped coil | First interosseous muscle (FDI) | RMT, MEP, short ICF and ICF | They investigate SICI and ICF with an ISI of 2 and 4 ms and 10 and 15 ms, respectively. Single-pulse stimulation was used to measure the RMT, using paired pulses with the Intensity of the conditioning stimulus as 80% of the RMT. For MEPs, the test stimuli were measured as 120% of the RMT. | 13 |
| Schwenkreis (2010) | M1 | Circular coil | Flexor muscle of the forearm | MT, CSP, SICI and ICF | The MT was defined as the minimum intensity to produce five motors evoked potentials > 50 mV out of 10 trials. The authors measured the ICI and ICF at inhibitory ISIs of 2 and 4 ms and facilitatory intervals of 10 and 15 ms. They also assessed the CSP by applying a stimulation 50% above the MT while the subject was contracting muscle with 20–30% of maximum voluntary strength. | 13 |
| Alventosa (2020) | M1 | Figure-of-eight-shaped | First dorsal interosseous | RMT | The authors only describe the RMT, and defined it as the minimum stimuli to elicit an evoked motor potential of at least 50 microvolts in 50% of the tests. | 9 |
| Salerno (2000) | M1 | Double cone coil | First dorsal interosseous muscle (FDI) and tibialis anterior | RMT, MEP, SICI and ICF | The TMS was performed with a “double cone” coil, targeting the FDI muscle. The stimulation was set at 150% of the relaxed motor threshold. The pair-pulse protocol was performed with 4, 25, 55, 85, 100, 155, 200, 255, and 355 ms intervals. | 13 |
| Tiwari (2021) | M1 | Figure-of-8 coil | Thumb muscles | RMT and MEP | The authors defined the RMT as the minimum stimulus to generate an evoked potential with a peak-to-peak amplitude of at least 50 mV at 50% of ten trials, and the MEP measure as the peak-to-peak amplitude elicited by averaging ten consecutive stimuli at 100% of the RMT. | 14 |
| Antal (2010) | M1 | Standard double 70 mm coil | FDI | RMT, active MT, CSP, SICI and ICF | RMT was defined as the minimum output to induce an MEP of 50 mV in at least three of six consecutive trials. The authors also described the active MT as the lowest stimulus intensity to generate three of six consecutive MEP in the tonically contracting FDI muscle. SICI was measured with ISIs of 2 and 4 ms, and ICF with ISIs of 9 and 12 ms. | 17 |
Note: CSP: cortical silent period, FDI: First dorsal interosseous, ICF: intracortical facilitation, ICI: intracortical inhibition, ISIs: interstimulus intervals, M1:Motor cortex, MEP: Motor evoked potential
MEP: motor evocate potential, MT: Motor threshold, RMT: resting motor threshold, TMS: transcranial magnetic stimulation, SICI: Short intracortical inhibition.