Abstract TP249: Functional MRI Guided Navigated TMS to Pharyngeal Motor Cortex

Abstract

Introduction: Optimization of the precise pharyngeal TMS target within the largest-scale central swallowing networks has been complicated. We addressed this by using state-of-the art fMRI and DTI combined with navigated transcranial magnetic stimulation(nTMS). Hypothesis: We hypothesized that by recording sEMG of lip orbicularis oris (OO) muscles with fMRI-guided nTMS will allow us readily to detect submental complex (SMC) muscles MEP to localize swallowing hotspot in M1. Methods: 8 healthy volunteer subjects (age = 25.714 ± 4.35, males: 2) conduced a voluntary saliva swallowing task modified from our previous study and a similarly sequenced lips pursing task. MEMPRAGE, HARDI as well as standard rsfMRI were performed to assess structural and functional connectivity. The motor cortices of the SMC and OO muscles in each hemisphere were targeted with a TMS neuronavigation that used a graphic user interface and a 3D optical digitizer to precisely position the coil over the cortical site based on individual swallowing/lips-task fMRI target. SMC and lip OO sEMG responses were detected with bipolar electrodes. Results: The fMRI-guided navigated (Figure 1 A and B) lips target was identified by the resting motor threshold compared with a traditionally measured hotspot (Figure 1 C and D). The simultaneous SMC response was detected to further clarify the estimate of the swallowing hotspot (Figure 1 E). The functional patterns of swallowing and connectivity in each hemisphere are demonstrated using resting fMRI combined fiber tractography (Figure 1 F, G, H and I). Conclusions: We provide evidence for the more precise and reliable targeting of pharyngeal motor cortex with the combination of fMRI and DTI and the assistance of fMRI-guided TMS on lips. This multimodal neuroimaging approach will enable visualization of a precise neuronal biomarker of central swallowing and thus allow the development of effective direct clinical treatment strategies for neurogenic swallowing disorders.