Abstract
This study was carried out to clarify how vocal abuse harms the vocal folds using vocal abuse rat model. 5 rats were vocalized 0.6 second a time, 650-1300 times a day for 7-48 days by electrical stimulation in a brain stem thought to be a final common pathway of the limbic system. Stimulation was ceased by fatigue in 3 rats, disconnection of an electrode in 1 and by death in 1. One of 5 rats which exhibited the most intense vocalization for 16 days (totally 12, 800 vocalization) changed its voice quality and abnormal microscopic features were found in the vocal folds. In both sides of the vocal folds, dense eosinophilic material and intersperse extravascular RBCs were found in deep portion of the lamina propria. The eosinophilic material was abundant in the mid membranous portion of the vocal folds but it decreased in serial section. This is thought to be a result of hemorrhage after vocal abuse and extravascular fibrin deposition.
