2020 Volume 24 Issue 2 Pages 143-152
Aim: This study aimed to clarify the relationship between swallowing dynamics and post-swallow residue in persons with severe spastic cerebral palsy (CP) and profound intellectual disability by comparing the movement of the mandible, hyoid bone and tongue in persons with CP and healthy adults.
Subjects and Method: Twenty-four healthy adults and 22 persons with severe spastic CP and profound intellectual disability underwent a videofluoroscopic examination of swallowing while swallowing 3 to 5 mL of paste food. The range of movement in the horizontal and vertical directions of the mandible and hyoid bone during pharyngeal swallow were measured using frame-by-frame analysis in the coordinate plane with the second and fourth cervical vertebrae as the reference line. Additionally, the duration of tongue contact with the palate and posterior pharyngeal wall along seven equiangular radial lines emanating from the center of the tongue were timed using frame-by-frame analysis. Furthermore, the post-swallow residue in the valleculae and piriform sinus was measured using a pixel-based measure. Referenced at the mean 95% confidence interval upper bound of the residue of the healthy adults, persons with severe spastic CP were classified into four groups: non-residue in valleculae (NRval), residue in valleculae (Rval), non-residue in piriform sinus (NRps), and residue in piriform sinus (Rps). The results were compared using the Kruskal-Wallis test with Dunn's multiple comparison test, and Spearman's correlation coefficients were calculated between the residue in each area and each measurement.
Results and Discussion: The mandible depressed greater and the duration of anterior tongue contact with the palate was shorter during pharyngeal swallow in persons with severe spastic CP than healthy adults. The Rval and Rps groups showed a smaller distance of anterior hyoid movement and longer duration of contact between the tongue base and pharyngeal wall than healthy adults. Residue in the valleculae correlated positively with mandibular downward distance, while the piriform sinus correlated negatively with the distance of anterior hyoid movement. It is considered that mandibular downward movement affected the tongue movement and resulted in failure of epiglottic inversion and pharyngeal constriction. In contrast, the abnormal tension of the head and neck and instability of the mandible caused failure of contraction of the geniohyoid muscle, which plays a critical role in the anterior hyoid movement, resulting in decreased movement of the anterior hyoid.
Conclusion: Residue in the valleculae was associated with mandibular downward distance and residue in the piriform sinus was associated with the distance of anterior hyoid movement in persons with severe spastic CP and profound intellectual disability.
