Eating plays a central role in everyday living and maintaining quality of life. Safe eating depends upon the integration of sensory information from the oral cavity to manage food. When oral sensation is negatively affected due to injury or disease, patients are at risk for not properly preparing solid foods for the swallow. The main sensory nerve of the tongue, the lingual nerve, is frequently compressed ("crushed") or transected during routine dental procedures (e.g., third molar removal) because of its anatomically unprotected location in the floor of the mouth. Lingual nerve injuries result in pain, altered or reduced sensation, and patients also report difficulties with feeding. However, the underlying biomechanical and functional basis of this oromotor dysfunction is unknown. The objective of this application is to understand how trauma to the lingual nerve impacts feeding behavior and the neural control and coordination of the tongue and jaw during feeding. The central hypothesis is that lingual nerve compression and transection injuries negatively impact sensorimotor integration of oral structures and, by extension, oral food management, but they do so in distinct ways. The effect of unilateral lingual nerve lesions will be investigated in the ig, an accepted animal model for human feeding biomechanics and oral function.
Specific Aim 1 will use biplanar fluoroscopy and a novel motion analysis method, X-ray Reconstruction of Moving Morphology (XROMM), to determine the impact of these injuries on oromotor behavior.
Specific Aim 2 will combine motion analysis with electromyography from jaw, oral and tongue muscles to understand the neurophysiological control of associated movements following these injuries.
Both aims will identify functional changes and compensatory mechanisms in the tongue and jaw following lingual sensory disturbances. This research is innovative because it focuses on 1) the effect of two distinct types of sensory disturbances on motor output and control and 2) the pre-swallowing feeding stages rather than on the oropharyngeal swallow, the focus of most feeding rehabilitation research. Unlike swallowing, the oral stages of feeding require bilaterally asymmetrical movements and motor control. This project is methodologically innovative in its use of XROMM, which allows the synchronization of high resolution 3D tongue and jaw movements with electromyograms from muscles controlling these movements. This is expected to lead to new insights into the role of the tongue during the oral stages of feeding and changes in its function resulting from sensory disturbances. The proposed research is significant because lingual nerve injuries are surprisingly common, and understanding their impact on oromotor output can benefit the design of rehabilitation strategies to restore oral function.
Lingual nerve injury occurs during routine dental procedures, producing pain and numbness in the tongue and impacting the patient's ability to feed. The proposed research will use an animal model to understand the physiological and functional consequences of lingual nerve injury for feeding. This study provides the necessary foundation for developing specific management and rehabilitation strategies for lingual nerve injuries.