The Passy Muir Swallowing Self Training Device

Participants were recruited who had chronic moderate to severe dysphagia following stroke or
radiation treatment for head and neck cancer. Their frequency of swallowing was transduced
with an accelerometer placed on the skin over the thyroid cartilage and inductive
plethysmography bands placed over the rib cage and abdomen. When laryngeal elevation
coincided with respiratory apnea a swallow was marked. Five different motor frequencies were
evaluated to determine their effect on participants frequency of swallowing (swallows per
minute). Frequencies were 30, 70, 110, and 150 Hz and a combination of 70 and 110 Hz. For
each vibratory frequency the number of swallows per minute occurring during stimulation was
compared with sham when the participant was wearing the device but the motor was not turned
on. The frequency fo swallowing during stimulation was compared with the frequency of
swallowing between stimulations. Visual analogue ratings of the urge to swallow and
discomfort were also measured after each condition. Other parameters were the pressure
between the motor and the skin (0, 2, 4, and 6 kPa) and swallow initiation time when
stimulation was on and when it was not. Swallowing frequency with continuous versus pulsed
stimulation was also compared.

Inclusion Criteria:

- Stroke or post radiation for the treatment of head and neck cancer

- Dysphagia with a score of 2 or greater on the Penetration/Aspiration Scale OR a Mann
Assessment of Swallowing Ability ordinal risk rating of "probable" or "definite"

Exclusion Criteria:

- Neck injury

- Epilepsy

- Neurological disorder other than stroke

- Psychiatric illness other than depression

- Uncontrolled gastroesophageal reflux disease

- Inability to communicate secondary to significant speech or language problems

- Inability to maintain alertness for 1 hour

- Significant health concerns that would put the participant at risk