Physiological Flow of Liquids Used in Dysphagia Management

Study Purpose:

For individuals with neurodegenerative conditions, such as Amyotrophic Lateral Sclerosis and Parkinson disease, swallowing impairment (i.e., dysphagia) is a common and serious symptom. Dysphagia places the affected individual at risk for secondary health consequences, including malnutrition and aspiration pneumonia, and negatively affects quality of life.

Thickened liquids are commonly recommended for individuals with dysphagia, as they flow more slowly and reduce the risk of entry into the airway. However, there is limited understanding about how changes in liquid thickness modulate swallowing physiology in individuals with neurodegenerative conditions, and previous reports have shown that increased liquid thickness may contribute to the accumulation of residue in the throat.

The purpose of this study is to explore swallowing physiology and function in individuals with neurodegenerative conditions, across five levels of liquid thickness (thin, slightly-thick, mildly-thick, moderately-thick, and extremely-thick), and to identify boundaries of "optimal liquid thickness", which maintain airway safety, without contributing to the accumulation of significant residue. Results from this study will help guide the clinical recommendations for thickened liquids in dysphagia management.

Study Status:

Not recruiting


Amyotrophic Lateral Sclerosis , Parkinson Disease , Dysphagia

Study Type:


Type of Intervention:


Intervention Name:






Study Chair(s)/Principal Investigator(s):

Catriona M Steele, PhD, University Health Network - Toronto Rehabilitation Institute, Emily K Plowman, PhD, University of Florida ID:


Neals Affiliated?


Coordinating Center Contact Information

University Health Network - Toronto Rehabilitation Institute

Toronto, Canada

Full Study Summary:

This observational research study will measure swallowing function in individuals with Amyotrophic Lateral Sclerosis or Parkinson's disease. The aims of this study are to (1) identify parameters of swallowing physiology that are associated with impaired swallowing safety and efficiency, and (2) explore how liquid thickness influences swallowing function.

Participation in this research study involves a single appointment at the University of Florida Swallowing Systems Core laboratory located at Shands Hospital, Gainesville. The appointment will last approximately 1 hour, and will involve tasks to measure tongue-strength, and a dynamic swallowing x-ray (known as videofluoroscopy) to evaluate swallowing function. A selection of demographic information (e.g., age, onset of symptoms) will also be recorded.

To measure tongue strength, participants will be given a disposable air-filled bulb and asked to perform a series of tongue presses, and swallow their saliva. Next, during the videofluoroscopy, participants will take sips of various liquids ranging in thickness from thin (like water), to extremely-thick (similar to the consistency of pudding or yogurt). The liquids will be mixed with a safe substance called barium, to make them visible on x-ray images. After the videofluoroscopy has been completed, each participant will have their tongue strength measured again, which will conclude their participation in the study.

Swallowing physiology will be measured from the videofluoroscopy images, post-hoc, by an experienced team of blinded raters.

Study Sponsor:

University Health Network, Toronto

Estimated Enrollment:


Estimated Study Start Date:

11 / 01 / 2017

Estimated Study Completion Date:

12 / 31 / 2020

Posting Last Modified Date:

09 / 15 / 2022

Date Study Added to

06 / 20 / 2017

Minimum Age:

18 Years

Maximum Age:

90 Years

Can participants use Riluzole?


Inclusion Criteria:

- Adults (18+) with a confirmed diagnosis of Amyotrophic Lateral Sclerosis (ALS) or Parkinson's disease (PD)

Exclusion Criteria:

- People with a prior medical history of stroke

- People with a prior medical history of acquired brain injury

- People with a prior medical history of spinal or spinal cord injury

- People with a prior medical history of cancer or surgery in the head and neck region

- People who have had radiation to the head and neck for cancer

- People who have a prior history of swallowing problems (e.g., from childhood, medical complication)

- People with significant breathing difficulties (e.g., rely on mechanical ventilation)

- People who rely solely on tube-feeding for all meals and nutrition

- People who have Type I (insulin-dependent) Diabetes

- Women who are pregnant

- People who have allergies to barium, potato starch, corn starch, xanthan gum, milk products, latex or dental glue

University of Florida

Gainesville, Florida 32611
United States