Abstract
Background:
Previous studies arguing that functional dysphagia could be explained by underlying neurobiological mechanisms are insufficient to explain brain regions that functionally interact in patients with functional dysphagia. Therefore, we investigated functional connectivity changes associated with functional dysphagia after applying facilitatory repetitive transcranial magnetic stimulation (rTMS) on the supplementary motor area (SMA).
Materials and Methods:
A patient with severe long-lasting functional dysphagia and 15 healthy controls participated in this study. A facilitatory 5 Hz rTMS protocol was applied to the patient's SMA. We performed functional magnetic resonance imaging (fMRI) using volitional swallowing tasks to investigate neural network changes before rTMS (pre-rTMS), immediately after rTMS, and 3 months later.
Results:
The pre-rTMS fMRI results of the patient showed extensive overactivation in the left-lateralized regions related to volitional swallowing compared with the healthy controls. Following rTMS, dysphagia symptoms partially improved. The patient showed positive connectivity with the bilateral cerebellum in the bilateral SMA seeds before rTMS treatment. Furthermore, left-lateralized overactivation was washed out immediately after completion of rTMS, and connectivity between the left SMA and left precentral gyrus recovered 3 months after rTMS treatment.
Conclusion:
Our findings confirm that functional dysphagia might be a neurobiological manifestation caused by maladaptive functional connectivity changes in brain structures related to swallowing. Furthermore, noninvasive brain modulation with rTMS over the SMA may facilitate functional connectivity changes between the cortical and subcortical regions. Accordingly, these changes will allow control of the movements related to swallowing and may lead to improved clinical symptoms.
Impact statement
In this study, the pre-repetitive transcranial magnetic stimulation (rTMS) functional magnetic resonance imaging results of the patient showed maladaptive brain activation and connectivity compared with those in healthy controls. Dysphagia symptoms partially improved after 5 Hz facilitatory rTMS on the supplementary motor area. Brain activation and functional connectivity changed immediately and 3 months after rTMS. Our findings confirm that functional dysphagia might be a neurobiological manifestation caused by maladaptive functional connectivity changes in brain structures related to swallowing. Furthermore, noninvasive brain modulation, such as rTMS, may facilitate functional connectivity changes between cortical and subcortical regions to control movements involved in swallowing disorders, and consequently, improve clinical symptoms.
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Supplementary Material
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