23 - Plasticity in the neural pathways for swallowing: role in rehabilitation of dysphagia

Summary

Dysphagia is defined as difficulty moving food and liquid from the mouth into the stomach. Traditionally this condition is divided into oropharyngeal and esophageal dysphagia to identify the locus of involvement. Oropharyngeal dysphagia is the focus of this chapter. It results when the structures or functions of the face, mouth, palate, pharynx, rostral esophagus, or larynx are altered by disease. For decades a feeding tube was the treatment of choice. Beginning in the 1960s and 1970s an array of clinical and instrumental evaluative techniques and medical, surgical, and behavioral approaches to its rehabilitation began appearing (Carrau and Murray, 1999; Huckabee and Pelletier, 1999). The evaluative approaches, including videofluoroscopy of the swallowing structures in action (Logemann, 1997) and endoscopic visualization during swallowing (Langmore, 2000), have increased understanding of the disturbed biomechanics responsible for impaired swallowing. Similarly the treatments for these biomechanical abnormalities have become increasingly powerful influences on the swallowing mechanism and on its neural controls in the nervous system.

This chapter's main purpose is to discuss the notion of neural plasticity in relation to dysphagia rehabilitation. The relative infancy of dysphagia science and the relatively short modern duration of excitement about the nervous system's plastic response to systematic stimulation mean that the data on changes in brain in response to swallowing treatment are in very short supply. They are, however, emerging, and the extant data will be reviewed. That review requires a context comprising brief discussion of the:

1. structures and neural controls on which swallowing depends,

2. causes of dysphagia,

3. approaches to evaluation, including measurement of treatment effect,

4. classification and description of the most frequently employed treatment approaches.