Assessing Corticospinal Pathways Using Transcranial Magnetic Stimulation

Abstract

Source: Charalambos, C. C., et al. Bilateral Assessment of the Corticospinal Pathways of the Ankle Muscles Using Navigated Transcranial Magnetic Stimulation. J. Vis. Exp. (2019)

This video demonstrates the method to assess corticospinal pathways of the leg muscles using transcranial magnetic stimulation (TMS). Rest and active muscle responses are recorded from one brain hemisphere to evaluate the contralateral corticomotor function of leg muscles.

Protocol

All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human welfare and have been reviewed by the local institutional review board.

1. Tonic Voluntary Activation (TVA) Testing

1. Determine bilaterally the maximum voluntary isometric contraction (MVIC) of each muscle. For each motion (i.e., dorsiflexion and plantarflexion), instruct subjects to maximally contract the contralateral examined muscle (e.g., right tibialis anterior, TA) 4 times (~5 s contractions separated by 60 s of rest) while the subject is seated in the posture described above.
2. Calc....

Results

Figure 1: Reconstructed Skin and Curvilinear Brain Models. (A) A skin model with four anatomic.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
2 Magstim stimulators (BiStim module)	The Magstim Company Limited; Whitland, UK		Used to elicit bilateral motor evoked potentials in tibialis anterior and soleus muscles.
Adaptive parameter estimation by sequential testing (PEST) for TMS	http://www.clinicalresearcher.org/software.htm		Used to determine motor thresholds.
Amplifier	Motion Lab Systems; Baton Rogue, LN, USA	MA-300	Used to amplify EMG data.
Double cone coil	The Magstim Company Limited; Whitland, UK	PN: 9902AP	Used to elicit bilateral motor evoked potentials in tibialis anterior and soleus muscles.
Signal	Cambridge Electronics Design Limited; Cambridge, UK	Version 6	Used to collect motor evoked potentials during rest and TVA.
Single double differential surface EMG electrodes	Motion Lab Systems; Baton Rogue, LN, USA	MA-411	Used to record EMG signals.
TMS frameless stereotaxy neuronavigation system	Brainsight 3, Rouge Research,Montreal, Canada		Used to navigate coil position during TMS assessment.