Assessing motor function in young children with transcranial magnetic stimulation

Area of Science:

• Neuroscience
• Pediatric Neurology
• Medical Imaging

Background:

• Assessing motor function in very young or developmentally delayed children noninvasively is challenging.
• Current methods like functional MRI (fMRI) and magnetoencephalography (MEG) require sedation, limiting their use.
• There is a need for reliable awake-based motor mapping techniques in pediatric populations.

Purpose of the Study:

• To evaluate the feasibility of using awake transcranial magnetic stimulation (TMS) for motor mapping in children under three years old.
• To compare TMS-based motor mapping with sedation-based MEG and fMRI.
• To explore TMS's ability to identify motor cortex abnormalities and plasticity.

Main Methods:

• Six children younger than three years underwent awake TMS motor mapping.
• Five children had passive sensorimotor mapping with MEG under sedation.
• Four children underwent fMRI during passive hand movements under sedation.

Main Results:

• TMS successfully elicited motor responses in contralateral hand muscles in 5 out of 6 patients.
• TMS-identified motor cortex locations correlated with MEG and fMRI findings.
• TMS revealed motor physiology abnormalities and demonstrated plasticity.
• Contralateral silent periods using TMS approximated motor cortex location when evoked responses were absent.

Conclusions:

• Awake TMS is a safe and feasible alternative to sedation-based MEG and fMRI for motor cortex localization in toddlers.
• TMS provides additional insights into motor pathophysiology and plasticity.
• Performance functioning level, rather than chronological age, better predicts successful TMS mapping outcomes.