Hemodynamic Signal Changes Accompanying Execution and Imagery of Swallowing in Patients with Dysphagia: A Multiple Single-Case Near-Infrared Spectroscopy Study

Abstract

In the present multiple case study, we examined hemodynamic changes in the brain in response to motor execution (ME) and motor imagery (MI) of swallowing in dysphagia patients compared to healthy matched controls using near-infrared spectroscopy (NIRS). Two stroke patients with cerebral lesions in the right hemisphere, two stroke patients with lesions in the brainstem, and two neurologically healthy control subjects actively swallowed saliva (ME) and mentally imagined to swallow saliva (MI) in a randomized order while changes in concentration of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) were assessed. In line with recent findings in healthy young adults, MI and ME of swallowing led to the strongest NIRS signal change in the inferior frontal gyrus in stroke patients as well as in healthy elderly. We found differences in the topographical distribution and time course of the hemodynamic response in dependence on lesion location. Dysphagia patients with lesions in the brainstem showed bilateral hemodynamic signal changes in the inferior frontal gyrus during active swallowing comparable to healthy controls. In contrast, dysphagia patients with cerebral lesions in the right hemisphere showed more unilateral activation patterns during swallowing. Furthermore, patients with cerebral lesions showed a prolonged time course of the hemodynamic response during MI and ME of swallowing compared to healthy controls and patients with brainstem lesions. Brain activation patterns associated with ME and MI of swallowing were largely comparable, especially for changes in deoxy-Hb. Hence, the present results provide new evidence regarding timing and topographical distribution of the hemodynamic response during ME and MI of swallowing in dysphagia patients and may have practical impact on future dysphagia treatment.

Motor imagery and swallowing: a systematic literature review

“…The countries which have published the research in question are different, however scholars of Austria and the Netherlands give signs that are involved in longitudinal research, improving topic [21][22][23] . In 2014 21 these researchers approached the use of MI by neuroimaging technique, checking changes in cerebral hemodynamics.…”

“…Moreover, it wouldn't be possible the admission of people with swallowing disorders 6,[21][22][23] . In the other hand, in the participants group with stroke, there was the requirement of dysphagia 6,22 , however with no others neurological and psychiatric disorders, with preserved capacity for understanding and communication 22 .…”

“…The use of motor imagery rehabilitation of swallowing shows to be a recent proposal, since the four selected articles are between the years 2014 and 2015 6,[21][22][23] . The literature clearly indicates the efficacy of MI as an adjuvant in motor rehabilitation of the upper limb in individuals with some neurological disorder [25][26][27] .…”

“…The time after the event has been described with a range 71-254 days in the study series of cases 22 , and, then considering a sample yet in subacute phase of the disease. Already in the manuscript with a single case of stroke 6 , the patient had chronic injury a year ago.…”

“…Considering the criteria of inclusion and exclusion, 4 articles were selected for this systematic review 6,[21][22][23] . The flowchart, which shows on detail, this process, follows the model of the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) For a better presentation of the results, the following variables of the selected articles were considered: author (year); country (sector); objective; subject; age; Inclusion criteria; Exclusion criteria; pathology (time, area, and side of brain injury); functional assessments; technique (imaging); strategy (motor imagery); major brain areas investigated; and results (Figures 2 and 3).…”