Swallowing neurorehabilitation: from the research laboratory to routine clinical application

The recent application of neurostimulation techniques to enhance the understanding of swallowing neural plasticity has expanded the focus of rehabilitation research from manipulation of swallowing biomechanics to manipulation of underlying neural systems. Neuromodulatory strategies that promote the brain's ability to reorganize its neural connections have been shown to hold promising potential to aid the recovery of impaired swallowing function. These techniques include those applied to the brain through the intact skull, such as transcranial magnetic stimulation or transcranial direct current stimulation, or those applied to the sensorimotor system in the periphery, such as neuromuscular electrical stimulation. Recent research has demonstrated that each of these techniques, either by themselves or in combination with these and other treatments, can, under certain circumstances, modify the excitability of motor representations of muscles involved in swallowing. In some studies, experimentally induced plastic changes have been shown to have functional relevance for swallowing biomechanics. However, the transition of novel, neuromodulatory brain stimulation techniques from the research laboratory to routine clinical practice is accompanied by a number of ethical, organizational, and clinical implications that impact professions concerned with the treatment of swallowing rehabilitation. In this article, we provide a brief overview of the neuromodulatory strategies that may hold potential to aid the recovery of swallowing function, and raise a number of issues that we believe the clinical professions involved in the rehabilitation of swallowing disorders must confront as these novel brain stimulation techniques emerge into clinical practice.