2001 年 8 巻 1 号 p. 25-30
The present study reports a newly developed laryngeal movement tracking system. The system consists of a metal rod, a displacement sensor, a plastic plate, and two identical magnets. The plastic plate was fixed to the skin over laryngeal prominence. The rod and magnets conduct the movement of the plate in relation to laryngeal movement to the sensor during swallowing. To evaluate the performance of the system, sensor outputs during swallowing were compared with recordings of masseter and digastric muscle EMGs in 6 young and healthy adults. Tests were conducted both in head-fixed (n = 3) and head-free (n = 3) conditions. Each subject was given a test fluid (2.0 ml of tea, at a temperature of 25°C) into the oral cavity and was instructed to swallow it. Actual motion picture of the laryngeal movement during swallowing was also recorded in the sagittal plane using a video tape recorder in one subject. The swallowing event in the laryngeal movement could be recorded as a biphasic curve by the system both in head-fixed and head-free conditions. Temporal analysis of the recorded curve together with the EMGs and the motion picture revealed that; the recorded curve reflects natural movement of the larynx during swallowing; and the inflections on the curve corresponded to laryngeal upward and downward movements respectively. The present results suggest that the developed system may be applicable to obtain temporal aspects of swallowing easily and safely in the clinic and laboratory.
