Swallowing skill training in neurodegenerative disease.

Rehabilitative intervention will be delivered face-to-face by University of Canterbury research personnel who also hold professional qualifications in Speech and Language Therapy. Intervention will comprise of 5 x 1 hour sessions per week for two weeks at the University of Canterbury Rose Centre for Stroke Recovery and Research. Treatment will use surface electromyography (sEMG) hardware and the custom designed Biofeedback in Strength and Skill Training (BiSSkiT) software (Huckabee, Sella, Jones & Han). The software is designed to incorporate skill training approaches with the aim to improve patients’ conscious control and precision over swallowing. Participants will be seated facing the computer screen. sEMG electrodes on a small self-adhesive patch, will be adhered under the participant’s chin over the submental muscles (geniohyoid, mylohyoid and anterior bellies of the digastric). The patch and electrodes will also be secured with medical tape to minimise interference from involuntary limb movements. The sEMG electrodes will be attached to a Verity Medical Myotrac Simplex Plus device, which then sends the sEMG signal either via Bluetooth to the computer and displays the sEMG data through the BiSSkiT software. Activity of the submental muscles will be displayed as a time by amplitude waveform. The parameters of the participant’s swallow are set in the first session using a calibration sequence where the participant completes five effortful swallows over 150 seconds. BiSSkit software utilises the amplitude of the calibration trials to provide a ‘target’ box randomly placed on the screen, between 30 and 70% of the participants’ average maximal amplitude during effortful swallowing. Each 30 second trial requires the participant to dry swallow such that the peak of the waveform falls within the centre of the target box. There are 10 trials per block, and eight blocks per session, separated by a 90 second rest periods. The accuracy and precision of the skill is targeted as the participant is required to consciously modify the timing and amplitude of their swallowing during each trial, based on feedback from a previous trial. They receive immediate auditory and visual feedback to inform them of the success of their performance. The task is made more difficult as the participant’s accuracy improves as the target box decreases by 10% following three consecutive successful ‘hits’. The box also increases in size by 10% following three consecutive ‘misses’ to reduce task difficulty. BiSSkiT software provides data on each trial, and a summary of 'hit' accuracy per one hour session. The researchers will monitor task adherence during the session, and examine summary data to ensure participants are completing the protocol as designed. For example, ensuring each peaked waveform corresponds to a full swallow.