Kinematic Strategies for Hyoid Movement in Rapid Sequential Swallowing Past videofluoroscopic and EMG evidence has shown that rapid sequential swallowing differs from discrete swallows, but our knowledge of the control strategies remains incomplete. This study examined in detail the interrelationships among kinematic variables to discern the strategies for deglutitive hyoid motion during discrete (5 cc, 10 cc, 20 cc, ... Research Article
Research Article  |   June 01, 2002
Kinematic Strategies for Hyoid Movement in Rapid Sequential Swallowing
 
Author Affiliations & Notes
  • Gloria Chi-Fishman, PhD
    National Institutes of Health Bethesda, MD
  • Barbara C. Sonies
    National Institutes of Health Bethesda, MD
  • Contact author: Gloria Chi-Fishman, PhD, Rm 6s235, Bldg. 10, OMF-PDB-RMD, Clinical Center, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892.
    Contact author: Gloria Chi-Fishman, PhD, Rm 6s235, Bldg. 10, OMF-PDB-RMD, Clinical Center, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892.×
  • Corresponding author: E-mail: gcf@nih.gov
Article Information
Swallowing, Dysphagia & Feeding Disorders / Speech / Research Articles
Research Article   |   June 01, 2002
Kinematic Strategies for Hyoid Movement in Rapid Sequential Swallowing
Journal of Speech, Language, and Hearing Research, June 2002, Vol. 45, 457-468. doi:10.1044/1092-4388(2002/036)
History: Received August 6, 2001 , Accepted February 25, 2002
 
Journal of Speech, Language, and Hearing Research, June 2002, Vol. 45, 457-468. doi:10.1044/1092-4388(2002/036)
History: Received August 6, 2001; Accepted February 25, 2002

Past videofluoroscopic and EMG evidence has shown that rapid sequential swallowing differs from discrete swallows, but our knowledge of the control strategies remains incomplete. This study examined in detail the interrelationships among kinematic variables to discern the strategies for deglutitive hyoid motion during discrete (5 cc, 10 cc, 20 cc, 30 cc) and rapid sequential (120 cc) swallowing tasks. Submental ultrasound was conducted with head and transducer stabilization on 30 healthy subjects (15 males, 15 females) in three age groups (20–39, 40–59, 60–79 yrs). Frame-by-frame changes in hyoid position were tracked from digitized images of 236 discrete and 318 rapid sequential swallows. Repeated-measures analyses of variance were conducted on a number of kinematic variables with corrections for multiple tests and comparisons. The main effect of task was significant for all variables except forward peak velocity. Per post hoc contrasts, rapid sequential swallows had significantly reduced maximal amplitude (maximal displacement), total distance, backward peak velocity, at-max and total durations, and time to backward peak velocity in comparison with discrete swallows of any volume. Amplitude "down-scaling" was the prominent kinematic strategy used to accomplish rapid sequential swallows in a shorter time while keeping forward peak velocity essentially unchanged. In contrast, amplitude "up-scaling" was the strategy for accommodating largervolume discrete swallows. Our results confirm built-in flexibility in the functional range of deglutitive hyoid motion.

Acknowledgments
The authors thank Mr. David Chow for developing an NIH-Image macro to expedite displacement tracking, Miss Julie Lei and Mr. Antony Hsu for assistance with image processing and data reduction, Drs. Betty Wang and Robert Wesley for statistical support, and Mr. Michael Harris-Love for technical consultation on muscle physiology.
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