Special communication
Swallowing Neurorehabilitation: From the Research Laboratory to Routine Clinical Application

https://doi.org/10.1016/j.apmr.2011.08.030Get rights and content

Abstract

Doeltgen SH, Huckabee M-L. 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.

Section snippets

Neuromodulatory Techniques in Swallowing Rehabilitation

The last decade in particular has seen the emergence of neuromuscular electrical stimulation (NMES) protocols in rehabilitation medicine. In general, NMES uses the application of pulsed electrical currents to muscles, nerves, or neuromuscular junctions with the therapeutic benefits thought to arise from improvements in muscle strength, stamina, and reaction time.17 Based on these general concepts, a number of differing protocols for applying NMES as a swallowing rehabilitation intervention have

Experimental Transcranial Brain Stimulation and Swallowing Rehabilitation

TMS and tDCS are the most common transcranial brain stimulation techniques, which stimulate neuronal networks within the brain through the intact skull with little or no discomfort. Both techniques are currently only used in experimental and clinical dysphagia research settings. TMS is based on concepts of electromagnetism, and can be applied either as single magnetic pulses (single- or paired-pulse TMS) or trains of magnetic pulses (repetitive TMS [rTMS]). Single-pulse TMS is used

Provision of Experimental Brain Stimulation Services in Clinical Dysphagia Rehabilitation

Although rTMS is already being tested in large-scale clinical trials as a treatment for other health conditions (eg, treatment-resistant depression and tinnitus), brain stimulation for the purpose of swallowing rehabilitation is currently only used by trained researchers conducting carefully monitored experimental protocols in a few research centers across the world. As more data are collected and if outcomes support the viability of neurostimulation protocols, the natural progression will be a

Professional Training: Guidelines For Ensuring Optimal Patient Care

The development of reliable and standardized brain stimulation protocols for routine clinical use should be accompanied by the development of guidelines for the training and application of these paradigms in clinical practice. To date, no international or national guidelines have been established that outline the training requirements for experimental brain stimulation. The International Federation of Clinical Neurophysiology is currently in the process of developing such guidelines.40 Although

Access to Stimulation Equipment: Practical Considerations

Unlike NMES devices, which are relatively inexpensive and can be operated by a patient or carer using clinician-defined protocols, experimental brain stimulation tools, especially rTMS, are expensive (>$10,000 U.S.) and cannot be patient operated. Therefore, patients will be required to attend the swallowing rehabilitation service providers' clinics to receive treatment. This may be clinically optimal, since paired application of brain stimulation with conventional swallowing rehabilitation

Conclusions

We conclude that the currently available research evidence suggests that experimental brain stimulation holds the potential for (1) inducing changes in the motor cortical areas that are involved in swallowing, which outlast the stimulation period, and importantly, (2) that such experimentally induced plastic changes can under certain circumstances be relevant for swallowing function. Given the promising potential that these novel rehabilitation techniques hold for improving the health, safety,

References (55)

  • S. Hamdy et al.

    Recovery of swallowing after dysphagic stroke relates to functional reorganization in the intact motor cortex

    Gastroenterology

    (1998)
  • M. Fujiu et al.

    Increased postoperative posterior pharyngeal wall movement in patients with anterior oral cancer: preliminary findings and possible implications for treatment

    Am J Speech Lang Pathol

    (1995)
  • R. Shaker et al.

    Augmentation of deglutitive upper esophageal sphincter opening in the elderly by exercise

    Am J Physiol

    (1997)
  • J.C. Rosenbek et al.

    A penetration-aspiration scale

    Dysphagia

    (1996)
  • J.A. Logemann

    Evaluation and treatment of swallowing disorders

    (1997)
  • S.E. Langmore et al.

    Fiberoptic endoscopic examination of swallowing safety: a new procedure

    Dysphagia

    (1988)
  • S.H. Doeltgen et al.

    Clinical measurement of pharyngeal surface electromyography: exploratory research

    Neurorehabil Neural Repair

    (2007)
  • S.G. Hiss et al.

    Timing of pharyngeal and upper esophageal sphincter pressures as a function of normal and effortful swallowing in young healthy adults

    Dysphagia

    (2005)
  • F. Gumbley et al.

    Effects of bolus volume on pharyngeal contact pressure during normal swallowing

    Dysphagia

    (2008)
  • S.H. Doeltgen et al.

    Evaluation of manometric measures during tongue-hold swallows

    Am J Speech Lang Pathol

    (2009)
  • M.A. Crary

    A direct intervention program for chronic neurogenic dysphagia secondary to brainstem stroke

    Dysphagia

    (1995)
  • M.L. Huckabee et al.

    Outcomes of swallowing rehabilitation in chronic brainstem dysphagia: a retrospective evaluation

    Dysphagia

    (1999)
  • M.A. Crary et al.

    Functional benefits of dysphagia therapy using adjunctive sEMG biofeedback

    Dysphagia

    (2004)
  • G. Alon

    Principles of electrical stimulation

  • G.D. Carnaby-Mann et al.

    Examining the evidence on neuromuscular electrical stimulation for swallowing

    Arch Otolaryngol

    (2007)
  • M.L. Huckabee et al.

    Emerging modalities in dysphagia rehabilitation: neuromuscular electrical stimulation

    N Z Med J

    (2007)
  • C.M. Steele et al.

    Electric stimulation approaches to the restoration and rehabilitation of swallowing: a review

    Neurol Res

    (2007)
  • Cited by (29)

    • Differences in brain networks during consecutive swallows detected using an optimized vertex–frequency algorithm

      2017, Neuroscience
      Citation Excerpt :

      Previous studies showed that the brain’s plasticity enables reorganization of the sensory and motor cortex (Robbins et al., 2008; Rosenkranz et al., 2008; Davenport et al., 2011). This reorganization is correlated with the rehabilitation of patients, who are suffering from some neurological conditions, such as stroke (Hamdy et al., 2000; Doeltgen and Huckabee, 2012). This leads us to speculate that the analysis of swallowing and swallowing disorders from a brain activity perspective could yield useful insights into how to exploit this reorganization to better rehabilitate neurogenic dysphagia.

    • Moderate-to-Severe Traumatic Brain Injury in Children: Complications and Rehabilitation Strategies

      2015, Journal of Pediatric Health Care
      Citation Excerpt :

      In addition to traditional compensatory techniques, recent approaches to treatment of swallow dysfunction have included use of electrical stimulation for modulation of neuronal systems affecting swallowing function. Trained speech language pathologists apply electrodes to the skin at the oropharyngeal neuromuscular junctions to deliver pulses of electrical stimulation to the muscles needed for swallowing in conjunction with ingestion of food or liquids (Doeltgen & Huckabee, 2012; Miller, 2011). Oral motor integrity plays an integral part in the ability to manage oral secretions as well.

    • Transcranial non-invasive brain stimulation in swallowing rehabilitation following stroke - A review of the literature

      2015, Physiology and Behavior
      Citation Excerpt :

      International collaboration must be encouraged to perform trials with sufficient numbers to accurately determine which paradigms may be superior to others in order to facilitate the eventual progression of the most effective and safe paradigms into clinical practice. As demonstrated in this review and previous commentaries [5,6], the current evidence base is in a process of rapid growth with the promising implication that NBS may provide an effective and safe adjunct to swallowing rehabilitation practice. There are several practical implications that accompany the eventual progression of NBS paradigms into clinical practice.

    • Magnetoencephalographic evidence for the modulation of cortical swallowing processing by transcranial direct current stimulation

      2013, NeuroImage
      Citation Excerpt :

      Venkatakrishnan et al. (2011) found effects to persist for up to 25 min post-tDCS which is presumably in the range of our study since MEG recording of all three swallow tasks took half an hour and the effects were still visible in the “challenged swallow task” which was conducted at last. Only recently, Doeltgen and Huckabee (2012) discussed whether this duration of after-effects could on its own ever be sufficient to be therapeutically meaningful. Since simultaneous training and neuromodulation are currently regarded as the most promising approach to promote the brain's intrinsic neural repair mechanisms, they concluded this time window of experimentally enhanced cortical excitability to be long enough to provide most conventional rehabilitative training protocols.

    View all citing articles on Scopus

    Supported by a Postdoctoral Australian Biomedical Research Fellowship from the National Health and Medical Research Council of Australia.

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.

    View full text