Page 154 - Functional impairment and cues for rehabilitation of head and neck cancer patients -

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Chapter 6
Standard exercises
The conventional effortful swallow (cES), Masako and Shaker exercise are commonly applied conventional swallowing exercises performed without an exercise tool providing external and progressive load. These exercises were used to compare the level of swallowing muscle activation during exercising with and without the SEA. Moreover, the SEA exercises were based on these exercises, and consequently we hypothesized that the same muscles would be activated.
During the cES exercise, the subject is instructed to forcefully swallow as if swallowing a large bolus. It is supposed to increase pharyngeal and tongue musculature strength and to improve the backward movement of the tongue base resulting in a better clearance of the vallecula (2).
During the Masako exercise, the subject has to stick out his/her tongue as far as possible and hold it in that position with their teeth or fingers while swallowing. The degree of tongue protrusion was not further standardized in this study. It is supposed to improve pharyngeal contraction by strengthening the glossopharyngeal muscle (36).
During the Shaker exercise, the subject lies in supine position and repetitively lifts his/her head for thirty times, followed by a period of rest of 30 seconds. Then the subject lifts his/her head for one minute, rests, and repeats the cycle (performing the head lift three times in total). The exercise is supposed to strengthen the suprahyoid muscles and therefore to improve opening of the upper esophageal sphincter (37), but also to activate the sternocleidomastoid muscles. Especially this exercises has shown to be effective in improving swallowing function (13, 14).
Procedure
Each subject performed the exercises in supine position in the MRI. The six exercises were performed on six separate days to avoid effects of the previous exercise disturbing the results of the next. The exercises were performed in a fixed order: CTAR+, JOAR+, ES+, cES, Masako and Shaker. First, the volunteers were asked to relax before the scan in order to get reliable resting-state T2 values for the swallow muscles. Then, an MRI-scan was made before the participant performed the exercise until exhaustion (i.e., the subject was not able to perform another repetition of the exercise). The second MRI-scan was made directly at completion of the exercise. To provide an indication of exercise duration, time between the pre and post exercise MRI was measured.
MRI acquisition
Regular T2-weighted images do not provide sufficient contrast to distinguish activated swallowing muscles after exercise. Image contrast is highly dependent on an optimal echo- time, which is muscle dependent, and very low for small T2 differences as observed in the swallowing muscles. We therefore chose the direct quantitative measurement of T2-values in milliseconds of the muscles by producing a T2-map. This map is a spatial distribution of voxel based T2-values associated with the anatomical features of the head and neck area.