Inclusion Criteria volunteers:
Healthy volunteers can participate in this study if they:
* Are aged between 18 and 80 years old
* Have no (history of) chronic disease/medication altering the gastrointestinal (GI) motility
* Have no (history of) gastric or gastrointestinal surgery (except appendectomy and cholecystectomy)
* Have no (history of) gastrointestinal disease or chronic GI symptoms (heartburn, indigestion/dyspepsia, bloating and constipation)
* Have FOIS score 7 or BEDQ score \<10 at baseline
* Provide witnessed written informed consent prior to any study procedure And if they do not meet any of the exclusion criteria listed below.
Exclusion Criteria volunteers:
Healthy volunteers will be excluded if they:
* Are aged \<18 years or \>80 years
* Have (any history of) a chronic disease/medication altering the GI motility
* Have (any history of) gastric or gastrointestinal surgery (except appendectomy and cholecystectomy)
* Have (any history of) gastrointestinal disease or chronic GI symptoms (heartburn, indigestion/dyspepsia, bloating and constipation)
* Have a FOIS score \<7 or a BEDQ score ≥ 10 at baseline
* Fail to provide witnessed written informed consent prior to any study procedure
Inclusion Criteria patients:
Dysphagic patients are eligible for study participation if they:
* Are admitted to the hospital because of acute stroke (acute means assessment within one month post stroke onset)
* Hemorrhagic and ischemic stroke
* Supratentorial and infratentorial stroke or have post-extubation dysphagia (PED) due to recent extubation following invasive mechanical ventilation (of any duration) by means of endotracheal tube or received (prolonged) intensive-care unit treatment leading to critical illness dysphagia due to (clinical suspicion of) critical illness polyneuropathy (CIP) and myopathy (CIM)
* Are aged between 18 and 85 years old
* Are medically stable, alert or arousable (Stroke: National Institutes of Health Stroke Scale (NIHSS) 0/1, ICU: Richmond Agitation-Sedation Scale (RASS) -1/0/+1 and Intensive Care Delirium Screening Checklist (ICDSC) \<4)
* Have clinical (oropharyngeal) dysphagia well identified using the FOIS/DSRS/ BEDQ/PAS at baseline. In line with earlier studies(16,27), we use the following criteria: a DSRS score of 6 or higher; or a FOIS-score equal to or lower than 5; or a BEDQ score of 10 or higher or (when no oral food intake is possible and DSRS score is 12/FOIS score is 1) a PAS-score of 4 or higher
* Give (or have a witness to give) voluntary written informed consent And if they do not meet any of the exclusion criteria listed hereunder.
Exclusion Criteria patients:
Patients will be excluded from study participation if:
* They are aged \<18 years or \>85 years
* They have pre-existing neurogenic dysphagia or a condition that can cause dysphagia (e.g. advanced dementia, Parkinson's Disease, myasthenia gravis, motor neuron disease…);
* They have pre-existing non-neurogenic dysphagia (e.g. cancer, …);
* They have normal swallowing at baseline assessed with FOIS/DSRS/BEDQ/PAS
* When they participate in another interventional study, they must inform the researcher or study staff. They agree not to participate in another study simultaneously without having informed the researcher or study staff, and that participation may be refused for justified reasons.
* They receive or have received within one month prior to the intended PES treatment any form of non-invasive brain stimulation or percutaneous electrical stimulation therapy to treat dysphagia. (This is no issue, since this type of treatment is not performed at University Hospitals Leuven.)
* It is not possible to pass a standard nasogastric tube, for example, nasal, oral, pharyngeal or oesophageal anatomical abnormalities that preclude passage of a feeding tube, oral intubation, history of oesophageal perforation, stricture, pouch or resection, maxillofacial surgery, partial or total laryngectomy
* They have a cardiac or respiratory condition that might render the insertion of a catheter into the throat unsafe (Severe heart failure, end stage chronic obstructive pulmonary disease (COPD). Atrial fibrillation does not render the insertion of a catheter unsafe)
* They have a permanently implanted electrical device
* They are pregnant
* They present with an oropharyngeal infection. This should be treated and resolved before the PES catheter is inserted
* They require an MRI scan during PES treatment. Insertion of the PES catheter should either be delayed until such time as the MRI has been completed, or the PES catheter should be removed and discarded and a new catheter inserted after the MRI is completed
