Can Swallowing Cerebral Neurophysiology Be Evaluated during Ecological Food Intake Conditions? A Systematic Literature Review

Abstract

Swallowing is a complex function that relies on both brainstem and cerebral control. Cerebral neurofunctional evaluations are mostly based on functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), performed with the individual laying down; which is a non-ecological/non-natural position for swallowing. According to the PRISMA guidelines, a review of the non-invasive non-radiating neurofunctional tools, other than fMRI and PET, was conducted to explore the cerebral activity in swallowing during natural food intake, in accordance with the PRISMA guidelines. Using Embase and PubMed, we included human studies focusing on neurofunctional imaging during an ecologic swallowing task. From 5948 unique records, we retained 43 original articles, reporting on three different techniques: electroencephalography (EEG), magnetoencephalography (MEG) and functional near infra-red spectroscopy (fNIRS). During swallowing, all three techniques showed activity of the pericentral cortex. Variations were associated with the modality of the swallowing process (volitional or non-volitional) and the substance used (mostly water and saliva). All techniques have been used in both healthy and pathological conditions to explore the precise time course, localization or network structure of the swallowing cerebral activity, sometimes even more precisely than fMRI. EEG and MEG are the most advanced and mastered techniques but fNIRS is the most ready-to-use and the most therapeutically promising. Ongoing development of these techniques will support and improve our future understanding of the cerebral control of swallowing.

Electroacupuncture at HT5 + GB20 produces stronger activation effect on swallowing cortex and muscle than single points

“…The fNIRS has benefits such as little restriction on test site or subject's body posture; strong noise resistance; simple pinning operation [ 14 ]; it can be used for examination in complex tasks; and its results are highly consistent with fMRI [ 15 ]. Currently, it is mainly used to investigate brain remodeling after stroke and less frequently to detect activation changes in the brain during swallowing [ 16 ].…”

Electroacupuncture at HT5 + GB20 promotes brain remodeling and significantly improves swallowing function in patients with stroke

“…fNIRS has benefits such as little restriction on the test site or subject's body posture; strong noise resistance; and simple pinning operation (Khan et al, 2022); it can measure cerebral blood flow in real-time during tasks continuously; results accord well with Fmri (Duan et al, 2012). However, it is more typically utilized in mental illnesses and post-stroke limb dysfunction, while it is less commonly employed in swallowing function (Gallois et al, 2022).…”