Tongue Muscle Response to Neuromuscular Diseases and Specific Pathologies

The tongue is the only muscular organ in the craniofacial region and plays fundamental roles in almost all oral motor functions, including drinking, ingestion, chewing, swallowing, respiration, and speech. A number of neuromuscular diseases, such as epilepsy, multiple sclerosis, cerebral palsy, muscular dystrophy, Parkinson’s and Huntington’s diseases, and myasthenia gravis, significantly affect tongue motor functions. These negative impacts include reduced or complete loss of control in moving the tongue (tongue displacement) and/or changing the shape of the tongue (tongue deformation), tongue spasm or convulsion, muscle dystonia, and ankyloglossia. Several sensational disorders may also occur due to these neuromuscular diseases, including burning tongue, loss of taste function (ageusia), decreased ability to taste (hypogeusia), and changes in taste (dysgeusia). In recent decades, extensive studies have demonstrated that tongue size, volume, position, and neuromuscular activity, especially in the tongue base, are significantly implicated in obstructive sleep apnea (OSA), a potential life-threatening disorder of breathing, which affects 2–4 % of the adult population (Schwab 2003; Schwab et al. 2003).