Tongue strength and exercise in healthy individuals and in head and neck cancer patients.

The tongue plays a critical role in bolus propulsion through the oral cavity and pharynx. This manuscript reviews the types of lingual impairment and overall oropharyngeal swallowing impairment present after treatment for head and neck cancer; specifically, surgery and primary chemoradiotherapy. Oral tongue impairment in surgically treated patients can include reduced range of motion, reduced control, and reduced ability to manipulate, seal, and propel a bolus into the pharynx. Tongue base impairment can result in reduced bolus clearance through the pharynx, resulting in pharyngeal residue and aspiration. The biologic effects of radiotherapy are described, with tissue fibrosis being a primary contributor to development of oropharyngeal swallow disorders. In patients treated with primary chemoradiotherapy, lingual strength has been found to be reduced, as has oral and pharyngeal structural movement during the swallow. The effects of skeletal muscle strengthening programs on muscle physiology are discussed, as are the effects of tongue strengthening exercise programs on tongue strength and swallowing. Future research needs are addressed.