Passy-Muir Swallowing Self Training Device to Enhance Recovery Post Stroke

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.