Impact of Sensory and Motor Defects on Oral Function in an Animal Model

Objective To evaluate the combined functional impact on swallowing of tongue sensory and motor loss using a rat model. Study Design Rats underwent selective neurectomies with transection of the motor (hypoglossal) nerve or motor and sensory (lingual) nerves. Postoperative functional parameters were followed for 2 weeks. Setting Translational research. Subjects and Methods Thirty-six adolescent male Wistar rats were divided into 4 groups: anesthetic (n = 6), sham surgery (n = 8), hypoglossal transection (n = 10), and hypoglossal and lingual transection (n = 12). Each morning on postoperative days 1 to 14, the water and food intake were quantified and the animal weighed. Two-way analyses of variance (SigmaPlot; SYSTAT, San Jose, California) were performed with factors of "group" and "postoperative day" (POD) to analyze whether a significant difference existed between water intake, pellet consumption, and weight change. Results The hypoglossal and lingual group consumed significantly less water during PODs 1 to 2 and significantly less food during PODs 1 to 3 than any other group. This established a significant difference in body weight between the hypoglossal and lingual group and all other groups for the duration of the study. Measured parameters in the hypoglossal group better approximated those of the control anesthetic and sham groups. Conclusions The addition of a sensory loss to a motor deficit involving the oral tongue results in a measurably significant difference in weight gain, a marker of function, compared with rats with only a motor deficit. Additional studies are needed to determine if there would be similar findings in a model of sensate vs asensate oral tongue reconstruction.