Researchers Use fMRI to Examine Neuroplasticity in Dysphagia Caused by PD

A case-control study in China used task-state functional magnetic resonance imaging (fMRI) to study brain changes of patients with Parkinson disease (PD) and dysphagia after 10 sessions of repetitive transcranial magnetic stimulation (rTMS) to examine effects on neuroplasticity.

Dysphagia, or impaired swallowing, in PD can lead to malnutrition, social impairment, anxiety and depression, aspiration/inhalation pneumonia, and reduced efficacy of any therapies. The incidence of PD-related dysphagia is about 82%, and it is progressive.

rTMS has been shown to improve impaired swallowing, but little is known about how rTMS affects corresponding brain regions.

The researchers examined data from 38 PD patients with dysphagia who received treatment at Beijing Rehabilitation Medicine Academy, Capital Medical University.

The patients received high-frequency rTMS of the motor cortex once per day for 10 successive days, and changes in brain activation were compared via fMRI in patients with PD and dysphagia and healthy controls.

Because of the risk of aspiration in these patients as well as the difficulty of conducting an autonomous water-swallowing task or a reflex water-swallowing task while lying down, researchers used a saliva-swallowing test in a block design to examine brain activation. In a 5-minute test, participants were presented with 5 task blocks and 5 rest blocks while undergoing fMRI.

Each block was 30 seconds long and alternated. During the task block, they viewed sentences that instructed them to swallow and press a button after each swallowing action and they were instructed to stop during each rest block.

Before treatment, patients with dysphagia showed greater activation in the precentral gyrus, supplementary motor area, and cerebellum compared with healthy controls. After treatment, this higher level of activity was weakened.

In addition, before treatment, patients with dysphagia showed decreased activation in the parahippocampal gyrus, caudate nucleus, and left thalamus compared with healthy controls. After treatment, these areas of the brain showed more activity.

PD patients with dysphagia reported improved subjective swallowing sensations after rTMS, the researchers reported. The researchers also said that they think the study “is the first to use task-state fMRI to study rTMS-induced changes in activation in PAD patients using the saliva-swallowing task and not the autonomous water-swallowing task or the reflex water-swallowing task.”

These findings suggest that swallowing function in patients with dysphagia improved after rTMS of the motor cortex and increased activation of the

caudate nucleus and parahippocampal gyrus, providing evidence of neuroplasticity and a potential therapeutic target for dysphagia in PD, the authors said.

Reference

Huang PL, Wang SJ, Sun RF, et al. Increased activation of the caudate nucleus and parahippocampal gyrus in Parkinson's disease patients with dysphagia after repetitive transcranial magnetic stimulation: a case-control study. Neural Regen Res. 2022; 17(5):1051–1058.