The effect of surface electrical stimulation on hyolaryngeal movement in normal individuals at rest and during swallowing

Office-based Electromyography-guided Botulinum Toxin Injection to the Cricopharyngeus Muscle: Optimal Patient Selection and Technique

Objectives:

This retrospective study was carried out to investigate the effectiveness and safety of office-based electromyography-guided injection of botulinum toxin in the cricopharyngeus muscle of patients who did not show upper esophageal sphincter passage in a swallowing study in spite of maximal swallowing rehabilitation.

Methods:

Thirty-six patients who showed no or limited ability to oral feed after maximum swallowing rehabilitation were enrolled. Video fluoroscopic swallowing study, flexible endoscopic evaluation of swallowing, disability rating scale, penetration aspiration score, and National Institutes of Health swallowing safety scale were used in the evaluation of dysphagia.

Results:

Success was defined as nondependence on gastrostomy for patients who previously were dependent on gastrostomy and improvement in disability rating scale score after botulinum toxin injections. The total success rate was 63.9%. The complication rate was very low, with only 1 patient showing temporary unilateral vocal fold paralysis. Botulinum toxin injection was more effective in patients with cranial nerve IX or X palsy than in those without it ( P = .006).

Conclusions:

This procedure can be a simple, safe, and effective tool in patients with cricopharyngeal dysfunction after swallowing rehabilitation, especially for cranial nerve IX or X palsy.

Respiratory muscle strength training and neuromuscular electrical stimulation in subacute dysphagic stroke patients: a randomized controlled trial

OBJECTIVE

To evaluate the effectiveness of inspiratory/expiratory muscle training (IEMT) and neuromuscular electrical stimulation (NMES) to improve dysphagia in stroke.

DESIGN

Prospective, single-blind, randomized-controlled trial.

SETTING

Tertiary public hospital.

SUBJECTS

Sixty-two patients with dysphagia were randomly assigned to standard swallow therapy (SST) (Group I, controls, n=21), SST+ IEMT (Group II, n=21) or SST+ sham IEMT+ NMES (Group III, n=20).

INTERVENTIONS

All patients followed a 3-week standard multidisciplinary rehabilitation program of SST and speech therapy. The SST+IEMT group's muscle training consisted of 5 sets/10 repetitions, twice-daily, 5 days/week. Group III's sham IEMT required no effort; NMES consisted of 40-minute sessions, 5 days/week, at 80Hz.

MAIN OUTCOMES

Dysphagia severity, assessed by Penetration-Aspiration Scale, and respiratory muscle strength (maximal inspiratory and expiratory pressures) at the end of intervention and 3-month follow-up.

RESULTS

Maximal respiratory pressures were most improved in Group II: treatment effect was 12.9 (95% confidence interval 4.5-21.2) and 19.3 (95% confidence interval 8.5-30.3) for maximal inspiratory and expiratory pressures, respectively. Swallowing security signs were improved in Groups II and III at the end of intervention. No differences in Penetration-Aspiration Scale or respiratory complications were detected between the 3 groups at 3-month follow-up.

CONCLUSION

Adding IEMT to SST was an effective, feasible, and safe approach that improved respiratory muscle strength. Both IEMT and NMES were associated with improvement in pharyngeal swallowing security signs at the end of the intervention, but the effect did not persist at 3-month follow-up and no differences in respiratory complications were detected between treatment groups and controls.

Pathophysiology of Radiation-Induced Dysphagia in Head and Neck Cancer

Oncologic treatments, such as curative radiotherapy and chemoradiation, for head and neck cancer can cause long-term swallowing impairments (dysphagia) that negatively impact quality of life. Radiation-induced dysphagia comprised a broad spectrum of structural, mechanical, and neurologic deficits. An understanding of the biomolecular effects of radiation on the time course of wound healing and underlying morphological tissue responses that precede radiation damage will improve options available for dysphagia treatment. The goal of this review is to discuss the pathophysiology of radiation-induced injury and elucidate areas that need further exploration.

Neuromuscular Electrical Stimulation for Treatment-Refractory Chronic Dysphagia in Tube-Fed Patients: A Prospective Case Series

OBJECTIVE

The aim of this study was to evaluate the role of neuromuscular electrical stimulation (NMES) in tube-fed patients with severe and chronic dysphagia refractory to traditional swallowing therapy (TT).

PATIENTS AND METHODS

A total of 11 consecutive dysphagic patients with tube-dependent nutrition and who had not responded to 6 months of TT were enrolled. Each patient received NMES for 30 min and TT for 30 min, twice a day, 5 days per week for 4 weeks. In order to evaluate the swallowing impairment, each patient underwent a fiberoptic endoscopic examination of swallowing immediately before the beginning of the treatment, after 2 weeks and after 4 weeks.

RESULTS

All enrolled patients managed to complete the swallowing treatment protocol for at least 2 weeks. After the 4-week treatment, 6 of 11 enrolled patients passed to a total oral diet with single or multiple consistencies despite specific food limitations or special preparation or compensation. Five patients, all affected by the most severe form of dysphagia, maintained tube-dependent nutrition.

CONCLUSION

NMES as adjunctive treatment to TT may offer a new possibility for the management of tube-fed patients who are refractory to TT.

Effect of submental sensitive transcutaneous electrical stimulation on virtual lesions of the oropharyngeal cortex

OBJECTIVE

The aim of this study was to assess the effect of submental sensitive transcutaneous electrical stimulation (SSTES) on pharyngeal cortical representation after the creation of an oropharyngeal cortical virtual lesion in healthy subjects.

METHODS

Motor-evoked potential amplitude of the mylohyoid muscles was measured with transcranial magnetic stimulation (TMS), the oropharyngeal cortex was mapped by cartography, and videofluoroscopic parameters of swallowing function were measured before and after SSTES (at the end of SSTES [0 min] and at 30 and 60 min), after the creation of a cortical virtual lesion (repetitive TMS, 1 Hz, 20 min on the dominant swallowing hemisphere).

RESULTS

Nine subjects completed the study. After 20 min of SSTES, motor-evoked potential amplitude increased (P<0.05), as did swallow reaction time after repetitive TMS, as seen on videofluoroscopy, which was reversed after electrical stimulation. On cortical mapping, the number of points with a cortical response increased in the dominant lesioned hemisphere (P<0.05), remaining constant at 60 min (P<0.05).

CONCLUSION

SSTES may be effective for producing cortical plasticity for mylohyoid muscles and reverses oropharyngeal cortical inhibition in healthy subjects. It could be a simple non-invasive way to treat post-stroke dysphagia.

Effect of transcutaneous electrical stimulation amplitude on timing of swallow pressure peaks between healthy young and older adults

OBJECTIVES

This study compared the effect of transcutaneous electrical stimulation (TES) amplitude on timing of lingual-palatal and pharyngeal peak pressures during swallowing in healthy younger and older adults.

BACKGROUND

Transcutaneous electrical stimulation amplitude is one parameter that may have different impacts on the neuromotor system and swallowing physiology. One aspect of swallowing physiology influenced by age is the timing of swallowing events. However, the effect of varying TES amplitudes on timing of swallowing physiology is poorly understood, especially in older adults.

MATERIALS AND METHODS

Thirty-four adults (20 younger and 14 older) swallowed 10 ml of nectar-thick liquid under three TES conditions: no stimulation, low-amplitude stimulation and high-amplitude stimulation. TES was delivered by surface electrodes on the anterior neck. Timing of pressure peaks for lingual-palatal contacts and pharyngeal pressures were measured under each condition.

RESULTS

A significant age × stimulation amplitude interaction was identified for the base of tongue (BOT) [F(2,62) = 5.087, p < 0.009] and the hypopharynx (HYPO) [F(2,62) = 3.277, p < 0.044]. At the BOT, low-amplitude TES resulted in slower swallows in the younger adults compared with no TES. In older adults, low-amplitude TES resulted in faster swallows compared with high-amplitude TES. At the HYPO, no significant differences were identified in pressure timing across the three TES amplitudes in both age groups. In each case, low-amplitude TES resulted in faster swallows in older adults compared with younger adults.

CONCLUSIONS

Transcutaneous electrical stimulation influences pharyngeal pressure timing differently in young and old people, which questions the appropriateness of using a 'one-size-fits-all' TES amplitude for rehabilitating people with dysphagia.

Uso da eletroestimulação na clínica fonoaudiológica: uma revisão integrativa da literatura

Resumo: Este trabalho tem como objetivo apresentar revisão integrativa de literatura sobre a aplicabilidade e o resultado do uso da eletroestimulação na prática clínica fonoaudiológica. Foram seguidos os preceitos do Cochrane Handbook, que envolveu a formulação da questão a ser investigada, localização e seleção dos estudos e avaliação crítica dos artigos. Foram utilizadas as bases de dados Medical Literature Analysis and Retrieval Sistem on-line (Medline), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), PubMed e Web of Science/ISI. Os descritores utilizados foram: "estimulação elétrica nervosa transcutânea", "estimulação elétrica", "disfagia", "transtornos de deglutição", "disfonia", "distúrbios da voz", "treinamento da voz" e "terapia por estimulação elétrica" em inglês, português e espanhol e suas combinações, no período entre 2003 e 2013. Os estudos analisados demonstraram que a eletroestimulação traz benefícios na reabilitação de pacientes na clínica fonoaudiológica, mas a metodologia utilizada nos estudos foi divergente e a população estudada muito heterogênea o que dificulta sua utilização clínica pelos profissionais da área. A eletroestimulação traz benefícios na reabilitação fonoaudiológica, porém novos estudos devem ser realizados utilizando uma amostra mais homogênea e descrevendo metodologia e técnicas fonoaudiológicas utilizadas nos procedimentos, a fim de comprovar seus resultados e viabilizar seu uso pelos profissionais da área.

Different Movement of Hyolaryngeal Structures by Various Application of Electrical Stimulation in Normal Individuals

Objective

To identify the differences in the movement of the hyoid bone and the vocal cord with and without electrical stimulation in normal subjects.

Methods

Two-dimensional motion analysis using a videofluoroscopic swallowing study with and without electrical stimulation was performed. Surface electrical stimulation was applied during swallowing using electrodes placed at three different locations on each subject. All subjects were analyzed three times using the following electrode placements: with one pair of electrodes on the suprahyoid muscles and a second pair on the infrahyoid muscles (SI); with placement of the electrode pairs on only the infrahyoid muscles (IO); and with the electrode pairs placed vertically on the suprahyoid and infrahyoid muscles (SIV).

Results

The main outcomes of this study demonstrated an initial downward displacement as well as different movements of the hyoid bone with the three electrode placements used for electrical stimulation. The initial positions of the hyoid bone with the SI and IO placements resulted in an inferior and anterior displaced position. During swallowing, the hyoid bone moved in a more superior and less anterior direction, resulting in almost the same peak position compared with no electrical stimulation.

Conclusion

These results demonstrate that electrical stimulation caused an initial depression of the hyoid bone, which had nearly the same peak position during swallowing. Electrical stimulation during swallowing was not dependent on the position of the electrode on the neck, such as on the infrahyoid or on both the suprahyoid and infrahyoid muscles.

The perturbation paradigm modulates error-based learning in a highly automated task: outcomes in swallowing kinematics

Traditional motor learning studies focus on highly goal-oriented, volitional tasks that often do not readily generalize to real-world movements. The goal of this study was to investigate how different perturbation paradigms alter error-based learning outcomes in a highly automated task. Swallowing was perturbed with neck surface electrical stimulation that opposes hyo-laryngeal elevation in 25 healthy adults (30 swallows: 10 preperturbation, 10 perturbation, and 10 postperturbation). The four study conditions were gradual-masked, gradual-unmasked, abrupt-masked, and abrupt-unmasked. Gradual perturbations increasingly intensified overtime, while abrupt perturbations were sustained at the same high intensity. The masked conditions reduced cues about the presence/absence of the perturbation (pre- and postperturbation periods had low stimulation), but unmasked conditions did not (pre- and postperturbation periods had no stimulation). Only hyo-laryngeal range of motion measures had significant outcomes; no timing measure demonstrated learning. Systematic-error reduction occurred only during the abrupt-masked and abrupt-unmasked perturbations. Only the abrupt-masked perturbation caused aftereffects. In this highly automated task, gradual perturbations did not induce learning similarly to findings of some volitional, goal-oriented adaptation task studies. Furthermore, our subtle and brief adjustment of the stimulation paradigm (masked vs. unmasked) determined whether aftereffects were present. This suggests that, in the unmasked group, sensory predictions of a motor plan were quickly and efficiently modified to disengage error-based learning behaviors.

Effect of Repetitive Transcranial Magnetic Stimulation According to the Stimulation Site in Stroke Patients With Dysphagia

Objective

To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) according to the stimulation site in subacute stroke patients with dysphagia.

Methods

This study was designed as a matched comparative study. Twenty-four patients who had dysphagia after ischemic stroke were recruited, and they were divided into two groups after matching for age and stroke lesion. The patients in group A received rTMS over the brain cortex where motor evoked potential (MEP) was obtained from the suprahyoid muscle. Group B received rTMS over the brain cortex where MEP was obtained from the abductor pollicis brevis muscle. rTMS was performed at 110% of MEP threshold, 10 Hz frequency for 10 seconds, and then repeated every minute for 10 minutes. Dysphagia status was measured by the Functional Dysphagia Scale (FDS), the Penetration-Aspiration Scale (PAS), and the Dysphagia Outcome and Severity Scale (DOSS) using the results of a videofluoroscopic swallowing study. These evaluations were measured before, immediately, and 4 weeks after rTMS.

Results

Group A showed significant improvement compared to group B in the DOSS score immediately and 4 weeks after rTMS. There were no significant differences in the changes of FDS and PAS scores between groups A and B immediately and 4 weeks after rTMS.

Conclusion

rTMS over a hot spot for the suprahyoid muscle caused more improvement in swallowing function when compared to that over the interconnected site.

Changes in hyolaryngeal movement and swallowing function after neuromuscular electrical stimulation in patients with Dysphagia

OBJECTIVE

To investigate immediate changes in hyolaryngeal movement and swallowing function after a cycle of neuromuscular electrical stimulation (NMES) on both submental and throat regions and submental placement alone in patients with dysphagia.

METHODS

Fifteen patients with dysphagia were recruited. First, videofluoroscopic swallowing study (VFSS) was performed before NMES. All patients thereafter received a cycle of NMES by 2 methods of electrode placement: 1) both submental and throat regions and 2) submental placement alone concomitant with VFSS. The Penetration-Aspiration Score (PAS) and the NIH-Swallowing Safety Scale (NIH-SSS) were measured for swallowing function.

RESULTS

During swallowing, hyolaryngeal descent significantly occurred by NMES on both submental and throat regions, and anterior displacement of hyolaryngeal complex was significant on submental placement alone. NMES on submental placement alone did not change the PAS and NIH-SSS. However, NMES on both submental and throat regions significantly reduced the NIH-SSS, although it did not change the PAS. Patients with no brainstem lesion and with dysphagia duration of <3 months showed significantly improved the NIH-SSS.

CONCLUSION

Immediate hyolaryngeal movement was paradoxically depressed after NMES on both submental and throat regions with significant reductions in the NIH-SSS but not the PAS, suggesting improvement in pharyngeal peristalsis and cricopharyngeal functions at the esophageal entry rather than decreased aspiration and penetration. The results also suggested that patients with dysphagia should be carefully screened when determining motor-level NMES.

Electrical neuromuscular stimulation in dysphagia: current status

PURPOSE OF REVIEW

To assess current information regarding the physiological effects of transcutaneous electrical stimulation (TES) on the neck and current evidence regarding the clinical effects of adding TES to dysphagia rehabilitation.

RECENT FINDINGS

Physiological studies have demonstrated that when electrical stimulation is applied on the throat it will lower the hyo-laryngeal complex and resist elevation needed for airway protection during swallowing. Submental TES has not been found to effectively elevate the hyo-laryngeal complex. Recent controlled clinical trials have had mixed results. Most indicate that TES is beneficial in the treatment of dysphagia; however, studies differ on whether these effects are greater than, equal to, or less than traditional therapy alone for the rehabilitation of swallowing.

SUMMARY

Currently TES for dysphagia is one of several tools available to the clinician for the rehabilitation of dysphagia. The two controlled clinical trials demonstrate that use of TES in dysphagia therapy is equivalent to traditional dysphagia therapy and of greater benefit only on one of several measures in one study. TES should be used only in patients who can overcome the resistive lowering of the hyo-laryngeal complex induced by TES which could place severely affected patients at greater risk of penetration.

Surface electrical stimulation perturbation context determines the presence of error reduction in swallowing hyolaryngeal kinematics

PURPOSE

Error-based learning (EBL) involves gradually reducing movement errors caused by a perturbation. When the perturbation has been unexpectedly removed, exaggerated movements occur in the opposite direction of a perturbation effect, known as aftereffects. Our goal was to determine whether the perturbation type impacts error reduction or aftereffects in swallowing hyolaryngeal kinematics.

METHOD

We perturbed peak hyolaryngeal elevation during swallowing in 16 healthy adults with surface electrical stimulation (SES) in 2 different ways during videofluoroscopy: intermittent SES (I-SES) was applied only during swallowing, and continuous SES (C-SES) was applied during swallowing and during interswallow intervals. In C-SES and I-SES, the onset and offset of the perturbation were unmasked.

RESULTS

Only the C-SES perturbation caused error reduction (gradually increasing peak elevation). Aftereffects were absent in both perturbations, unlike findings from our previous study with masked perturbation. Furthermore, the duration of laryngeal vestibule closure (dLVC) increased during the I-SES perturbation but was unchanged during C-SES perturbation.

CONCLUSION

EBL of swallowing airway protection events was strongly influenced by the context of the perturbation. These findings also elucidate how the relationship among critical swallowing airway protection events (hyoid peak, laryngeal peak, and dLVC) can be modified during EBL.

Adoption into clinical practice of two therapies to manage swallowing disorders: exercise-based swallowing rehabilitation and electrical stimulation

PURPOSE OF REVIEW

To review recent literature depicting a shift in dysphagia rehabilitation in adults. Distinguishing rehabilitation from compensation in dysphagia management, a review of basic exercise principles is followed by description of recent publications depicting exercise-based therapies. Subsequently, transcutaneous electrical stimulation (TES) is reviewed as it may contribute to exercise-based dysphagia rehabilitation in adults.

RECENT FINDINGS

Surveys have documented extensive variability in the clinical application of dysphagia therapy techniques. Despite this variability, two trends are emerging in dysphagia rehabilitation research: documentation of physiologic and functional changes within the swallowing mechanism subsequent to therapy; and prophylactic exercise-based therapies. In addition, extensive efforts have emerged describing the potential application of TES in dysphagia rehabilitation. Though results of these efforts are conflicted, TES may serve a useful role as an adjunct to well developed exercise-based rehabilitation for dysphagia.

SUMMARY

The focus of dysphagia rehabilitation in adults is changing. Current efforts indicate that exercise-based therapies should incorporate multiple principles of exercise physiology and document physiologic change within the impaired swallowing mechanism. TES may function as an adjunctive modality; however, current practices should be evaluated to develop additional parameters of stimulation that are focused toward specific dysphagia impairments.

Immediate effects of transcutaneous electrical stimulation on physiological swallowing effort in older versus young adults

OBJECTIVE

This study compared the immediate impact of different transcutaneous electrical stimulation (TES) amplitudes on physiological swallowing effort in healthy older adults versus young adults.

BACKGROUND

Swallowing physiology changes with age. Reduced physiological swallowing effort in older adults including lower lingua-palatal and pharyngeal pressures may increase risk for swallowing dysfunction (i.e. dysphagia). Transcutaneous electrical stimulation (TES) has been advocated as an adjunctive modality to enhance outcomes in exercise-based therapy for individuals with dysphagia. However, significant variation in how TES is applied during therapy remains and the physiological swallowing response to TES is poorly studied, especially in older adults.

MATERIALS AND METHODS

Physiological change in swallowing associated with no stimulation, sensory stimulation and motor stimulation was compared in 20 young adults versus 14 older adults. Lingua-palatal and pharyngeal manometric pressures assessed physiological swallowing effort.

RESULTS

Multivariate analyses identified interactions between age and stimulation amplitude on lingual and pharyngeal functions. Motor stimulation reduced anterior tongue pressure in both age groups but selectively reduced posterior lingua-palatal pressures in young adults only. Sensory stimulation increased base of tongue (BOT) pressures in older adults but decreased BOT pressures in young adults. Motor stimulation increased hypopharyngeal pressures in both groups.

CONCLUSION

Age and TES level interact in determining immediate physiological responses on swallow performance. A one-size-fit-all approach to TES in dysphagia rehabilitation may be misdirected.

Dysphagia Management in Acute and Sub-acute Stroke

Swallowing dysfunction is common after stroke. More than 50% of the 665 thousand stroke survivors will experience dysphagia acutely of which approximately 80 thousand will experience persistent dysphagia at 6 months. The physiologic impairments that result in post-stroke dysphagia are varied. This review focuses primarily on well-established dysphagia treatments in the context of the physiologic impairments they treat. Traditional dysphagia therapies including volume and texture modifications, strategies such as chin tuck, head tilt, head turn, effortful swallow, supraglottic swallow, super-supraglottic swallow, Mendelsohn maneuver and exercises such as the Shaker exercise and Masako (tongue hold) maneuver are discussed. Other more recent treatment interventions are discussed in the context of the evidence available.

Novel neuromuscular electrical stimulation system for treatment of dysphagia after brain injury

The purpose of this study was to compare the effects of a novel neuromuscular electrical stimulation (NMES) to the effects of conventional treatment in patients with dysphagia after brain injury. In total, 26 patients were non-randomly divided into an experimental group (n = 12) and a control group (n = 14). The experimental group received NMES intervention followed by conventional treatment, including thermal-tactile stimulation with intensive repetition of a dry-swallow task. The control group received conventional treatment without NMES. NMES at a fixed pulse duration of 50 μs and a frequency of 50 Hz was delivered over the skin areas above the motor point of the target muscles, i.e., the bilateral geniohyoid, mylohyoid/anterior belly of the digastric, and thyrohyoid muscles, using a high-voltage pulsed-current device. The two groups received 40-min treatments once a day, 5 days per week, for 8 weeks. Outcome, assessed before and 8 weeks after treatment, was evaluated with regard to the videofluoroscopic dysphagia scale (VDS), the anterior and superior displacement of the hyoid bone and larynx, and the functional oral intake scale. Both groups exhibited improvement, but the experimental group exhibited more significant improvement in the displacement of the hyoid bone and larynx, VDS-total score, and VDS-pharyngeal score than the control group did. The results suggest that NMES combined with conventional treatment is superior to conventional treatment alone in patients with dysphagia following treatment for brain injury. Further investigations are necessary to examine the effects of NMES in patients with more varied types of diseases.

Differential psychophysiological interactions of insular subdivisions during varied oropharyngeal swallowing tasks

Abstract The insula is a highly integrated cortical region both anatomically and functionally. It has been shown to have cognitive, social-emotional, gustatory, and sensorimotor functions. Insular involvement in both normal and abnormal swallowing behavior is well established, yet its functional connectivity is unclear. Studies of context-dependent connectivity, or the connectivity during different task conditions, have the potential to reveal information about synaptic function of the insula. The goal of this study was to examine the functional connectivity of specific insular regions (ventral anterior, dorsal anterior, and posterior) with distant cortical regions during four swallowing conditions (water, sour, e-stim, and visual biofeedback) using generalized psychophysiological interactions (gPPI). In 19 healthy adults, we found that the visual biofeedback condition was associated with the most and strongest increases in functional connectivity. The posterior insula/rolandic operculum regions had the largest clusters of increases in functional connectivity, but the ventral anterior insula was functionally connected to a more diverse array of cortical regions. Also, laterality assessments showed left lateralized increases in swallowing functional connectivity. Our results are aligned with reports about the insula's interconnectivity and extensive involvement in multisensory and cognitive tasks.

[Neuromuscular electric stimulation therapy in otorhinolaryngology]

BACKGROUND

Animal experiments have shown that after specific nerve traumatization, neuromuscular electrostimulation (NMES) can promote nerve regeneration and reduce synkinesia without negatively interfering with normal regeneration processes. NMES is used routinely in physical rehabilitation medicine.

METHODS

This systematic literature search in the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, the DAHTA database, the Health Technology Assessment Database and MEDLINE or PubMed considered studies on the use of NMES in otorhinolaryngology that have been published in German or English.

RESULTS

The search identified 180 studies. These were evaluated and relevant studies were included in the further evaluation.

DISCUSSION

In the fields of otorhinolaryngology and phoniatry/paediatric audiology, clinical studies investigating the effects of NMES on facial and laryngeal paresis, as well as dysphonia and dysphagia have been carried out. The evidence collected to date is encouraging; particularly for the treatment of certain forms of dysphagia and laryngeal paresis.

Surface electrical stimulation for treating swallowing disorders after stroke: a review of the stimulation intensity levels and the electrode placements

Neuromuscular electrical stimulation (NMES) for treating dysphagia is a relatively new therapeutic method. There is a paucity of evidence about the use of NMES in patients with dysphagia caused by stroke. The present review aimed to introduce and discuss studies that have evaluated the efficacy of this method amongst dysphagic patients following stroke with emphasis on the intensity of stimulation (sensory or motor level) and the method of electrode placement on the neck. The majority of the reviewed studies describe some positive effects of the NMES on the neck musculature in the swallowing performance of poststroke dysphagic patients, especially when the intensity of the stimulus is adjusted at the sensory level or when the motor electrical stimulation is applied on the infrahyoid muscles during swallowing.

Electrical stimulation in treatment of pharyngolaryngeal dysfunctions

OBJECTIVE

Neuromuscular electrical stimulation (NMES) has been proposed in the treatment of laryngopharyngeal dysfunctions (dysphonia, dyspnoea, dysphagia) for more than 40 years. Several studies have investigated possible therapeutic effects. Some researchers described favourable results, whereas others did not find relevant benefits. This article aims to review available studies to give an overview regarding the current state of knowledge.

METHODS

We conducted a selective literature search using PubMed.

RESULTS

In total, 356 papers were identified: 6 case reports, 11 reviews, 43 prospective clinical trials and 3 retrospective trials were found.

CONCLUSION

Due to different stimulation protocols, electrode positioning and various underlying pathological conditions, summarizing the present studies appears to be difficult. However, there is evidence that NMES is a valuable adjunct in patients with dysphagia and in patients with vocal fold paresis. Nevertheless, more empirical data is needed to fully understand the benefits provided by NMES. Further research suggestions are put forward.

Effect of surface sensory and motor electrical stimulation on chronic poststroke oropharyngeal dysfunction

BACKGROUND

Chronic poststroke oropharyngeal dysfunction (OD) is a common condition, leading to severe complications, including death. Treatments for chronic poststroke OD are scarce. The aim of our study was to assess and compare the efficacy and safety of treatment with surface electrical stimulation (e-stim) at sensory and motor intensities in patients with chronic poststroke OD.

METHODS

Twenty chronic poststroke patients with OD were randomly assigned to (i) sensory e-stim (treatment intensity: 75% of motor threshold) or (ii) motor e-stim (treatment intensity: motor threshold). Patients were treated during 10 days, 1 h/day. Videofluoroscopy was performed at the beginning and end of the study to assess signs of impaired efficacy and safety of swallow and timing of swallow response.

KEY RESULTS

Patients presented advanced age (74.95 ± 2.18), 75% were men. The mean days poststroke was 336.26 ± 89.6. After sensory stimulation, the number of unsafe swallows was reduced by 66.7% (p < 0.001), the laryngeal vestibule closure time by 22.94% (p = 0.027) and maximal vertical hyoid extension time by 18.6% (p = 0.036). After motor stimulation, the number of unsafe swallows was reduced by 62.5% (p = 0.002), the laryngeal vestibule closure time by 38.26% (p = 0.009) and maximal vertical hyoid extension time by 24.8% (p = 0.008). Moreover, the motor stimulus reduced the pharyngeal residue by 66.7% (p = 0.002), the upper esophageal sphincter opening time by 39.39% (p = 0.009), and increased bolus propulsion force by 211.1% (p = 0.008). No serious adverse events were detected during the treatment.

CONCLUSIONS & INFERENCES

Surface e-stim is a safe and effective treatment for chronic poststroke dysphagic patients.

Functional assessment and rehabilitation: how to maximize outcomes

The number of oral cavity and oropharyngeal cancer survivors is rising. By 2030, oropharyngeal cancers are projected to account for almost half of all head and neck cancers. Normal speech, swallowing, and respiration can be disrupted by adverse effects of tumor and cancer therapy. This review summarizes clinically distinct functional outcomes of patients with oral cavity and oropharyngeal cancers, methods of pretreatment functional assessments, strategies to reduce or prevent functional complications, and posttreatment rehabilitation considerations.

Kinematic effects of hyolaryngeal electrical stimulation therapy on hyoid excursion and laryngeal elevation

The purpose of this study was to assess the effect of repeated sessions of electrical stimulation therapy (EST) on the neck muscles with respect to the stimulation site by using quantitative kinematic analysis of videofluoroscopic swallowing studies (VFSS) in dysphagia patients with acquired brain injury. We analyzed 50 patients in a tertiary hospital who were randomly assigned into two different treatment groups. One group received EST on the suprahyoid muscle only (SM), and the other group received stimulation with one pair of electrodes on the suprahyoid muscle and the other pair on the infrahyoid muscle (SI). All patients received 10-15 sessions of EST over 2-3 weeks. The VFSS was carried out before and after the treatment. Temporal and spatial parameters of the hyoid excursion and laryngeal elevation during swallowing were analyzed by two-dimensional motion analysis. The SM group (n = 25) revealed a significant increase in maximal anterior hyoid excursion distance (mean ± SEM = 1.56 ± 0.52 mm, p = 0.008) and velocity (8.76 ± 3.42 mm/s, p = 0.017), but there was no significant increase laryngeal elevation. The SI group (n = 25), however, showed a significant increase in maximal superior excursion distance (2.09 ± 0.78 mm, p = 0.013) and maximal absolute excursion distance (2.20 ± 0.82 mm, p = 0.013) of laryngeal elevation, but no significant increase in hyoid excursion. There were no significant differences between the two groups with respect to changes in maximal anterior hyoid excursion distance (p = 0.130) and velocity (p = 0.254), and maximal distance of superior laryngeal elevation (p = 0.525). EST on the suprahyoid muscle induced an increase in anterior hyoid excursion, and infrahyoid stimulation caused an increase in superior laryngeal elevation. Hyolaryngeal structural movements were increased in different aspects according to the stimulation sites. Targeted electrical stimulation based on pathophysiology is necessary.

Tongue muscle plasticity following hypoglossal nerve stimulation in aged rats

INTRODUCTION

Age-related decreases in tongue muscle mass and strength have been reported. It may be possible to prevent age-related tongue muscle changes using neuromuscular electrical stimulation (NMES). Our hypothesis was that alterations in muscle contractile properties and myosin heavy chain composition would be found after NMES.

METHODS

Fifty-four young, middle-aged, and old 344/Brown Norway rats were included in this study. Twenty-four rats underwent bilateral electrical stimulation of the hypoglossal nerves for 8 weeks and were compared with control or sham rats. Muscle contractile properties and myosin heavy chain (MHC) in the genioglossus (GG), styloglossus (SG), and hyoglossus (HG) muscles were examined.

RESULTS

Compared with unstimulated control rats, we found reduced muscle fatigue, increased contraction and half-decay times, and increased twitch and tetanic tension. Increased type I MHC was found, except for in GG in old and middle-aged rats.

CONCLUSION

Transitions in tongue muscle contractile properties and phenotype were found after NMES.

Relationship between Class III malocclusion and hyoid bone displacement during swallowing: a cine-magnetic resonance imaging study

Objective

The displacement of the hyoid bone (HB) is a critical biomechanical component of the swallowing function. The aim of this study was to evaluate the swallowing-induced vertical and horizontal displacements of the HB in subjects with 2 different magnitudes of skeletal Class III malocclusion, by means of real-time, balanced turbo-field-echo (B-TFE) cine-magnetic resonance imaging.

Methods

The study population comprised 19 patients with mild skeletal Class III malocclusion, 16 with severe skeletal Class III malocclusion, and 20 with a skeletal Class I relationship. Before the commencement of the study, all subjects underwent cephalometric analysis to identify the nature of skeletal malformations. B-TFE images were obtained for the 4 consecutive stages of deglutition as each patient swallowed 10 mL of water, and the vertical and horizontal displacements of the HB were measured at each stage.

Results

At all stages of swallowing, the vertical position of the HB in the severe Class III malocclusion group was significantly lower than those in the mild Class III and Class I malocclusion groups. Similarly, the horizontal displacement of the HB was found to be significantly associated with the severity of malocclusion, i.e., the degree of Class III malocclusion, while the amount of anterior displacement of the HB decreased with an increase in the severity of the Class III deformity.

Conclusions

Our findings indicate the existence of a relationship between the magnitude of Class III malocclusion and HB displacement during swallowing.

Human hyolaryngeal movements show adaptive motor learning during swallowing

The hyoid bone and larynx elevate to protect the airway during swallowing. However, it is unknown whether hyolaryngeal movements during swallowing can adjust and adapt to predict the presence of a persistent perturbation in a feed-forward manner (adaptive motor learning). We investigated adaptive motor learning in nine healthy adults. Electrical stimulation was administered to the anterior neck to reduce hyolaryngeal elevation, requiring more strength to swallow during the perturbation period of this study. We assessed peak hyoid bone and laryngeal movements using videofluoroscopy across thirty-five 5-ml water swallows. Evidence of adaptive motor learning of hyolaryngeal movements was found when (1) participants showed systematic gradual increases in elevation against the force of electrical stimulation and (2) hyolaryngeal elevation overshot the baseline (preperturbation) range of motion, showing behavioral aftereffects, when the perturbation was unexpectedly removed. Hyolaryngeal kinematics demonstrates adaptive, error-reducing movements in the presence of changing and unexpected demands. This is significant because individuals with dysphagia often aspirate due to disordered hyolaryngeal movements. Thus, if rapid motor learning is accessible during swallowing in healthy adults, patients may be taught to predict the presence of perturbations and reduce errors in swallowing before they occur.

The effects of botulinum toxin injections into the cricopharyngeus muscle of patients with cricopharyngeus dysfunction associated with pharyngo-laryngeal weakness

This prospective, open study was carried out in order to assess changes in the swallowing and dietary status after injection of Botulinum toxin A (BoNT-A) into the upper esophageal sphincter (UES) in a series of patients with cricopharyngeus (CP) muscle dysfunction associated with pharyngo-laryngeal weakness during at least 1 year follow-up after treatment. Patients who had a cricopharyngeus (CP) muscle dysfunction associated with pharyngo-laryngeal weakness and who were at risk for aspiration were included in the study. The upper border of the cricoid cartilage was identified and the CP muscle localized using a standard electromyogram (EMG). The dose of BoNT-A was determined depending on the results of EMG performed just before the injection. Outcomes were assessed by the penetration-aspiration scale (PAS), the level of residue in the pyriform sinus and the National Institute of Health-Swallow Safety Scale (NIH-SSS) on a video fluoroscopic swallowing (VFSS) assessment, the patient's subjective impressions of their ability to swallow by the Deglutition Handicap Index (DHI), and changes in dietary status by the Functional Oral Intake Scale. Eleven patients underwent the complete assessment of swallowing function at 1, 3, 6, and 12 months. After the first set of treatment, seven patients had a good response and four did not respond. A significant decrease in the PAS score (p = 0.03), the amount of residue (p = 0.04) and the NIH-SSS score (p = 0.03) was observed 3 months after the injection in comparison with the first VFSS before the treatment. A relapse of dysphagia occurred in 3 out of the 11 treated patients; at 3 and 4 months for 2 patients with a Wallenberg syndrome, and at 11 months for a patient with cranial nerve paralysis after a surgery for a glomus tumor. Two of them underwent a second injection. One patient had a good response and remained stable for at least 1 year. The second did not respond either to the second injection or to a myotomy of the cricopharyngeal muscle. The third one is waiting for further surgery (myotomy). Therefore, at the end of the study and after a follow-up of at least 12 months, 5 patients out of the 11 enrolled had a good result. Percutaneous injection of BoNT-A into the UES can be a useful solution to improve cricopharyngeal dysfunction, despite the underlying pharyngo-laryngeal weakness.

Electrical stimulation and swallowing: how much do we know?

Consequences of dysphagia substantially reduce quality of life, increase the risk of medical complications and mortality, and pose a substantial cost to healthcare systems. As a result, it is of no wonder that the clinical and scientific communities are showing interest in new avenues for dysphagia rehabilitation. Electrical stimulation (e-stim) for the treatment of swallowing impairments is among the most studied swallowing interventions in the published literature, yet many unanswered questions about its efficacy remain. In the meantime, many speech-language pathologists who treat dysphagia are attending educational and training sessions to obtain certifications to use this technique. Here, we review the values and limitations of the published literature on the topic of e-stim for swallowing to assist clinicians in decision making in their clinical practice. The discussion provides a review of swallowing anatomy and physiology, the fundamentals of e-stim, and information essential for the readers' independent critique of these studies--all of which are crucial for evaluating the possible effects of e-stim.

Dysphagia and aspiration in children

Aspiration is a significant cause of respiratory morbidity and sometimes mortality in children. It occurs when airway protective reflexes fail, especially, when dysphagia is also present. Clinical symptoms and physical findings of aspiration can be nonspecific. Advances in technology can lead to early diagnosis of dysphagia and aspiration, and, new therapeutic advances can significantly improve outcome and prognosis. This report first reviews the anatomy and physiology involved in the normal process of swallowing. Next, the protective reflexes that help to prevent aspiration are discussed followed by the pathophysiologic events that occur after an aspiration event. Various disease processes that can result in dysphagia and aspiration in children are discussed. Finally, the various methods for diagnosis and treatment of dysphagia in children are reviewed.

Adaptation of swallowing hyo-laryngeal kinematics is distinct in oral vs. pharyngeal sensory processing

Before a bolus is pushed into the pharynx, oral sensory processing is critical for planning movements of the subsequent pharyngeal swallow, including hyoid bone and laryngeal (hyo-laryngeal) kinematics. However, oral and pharyngeal sensory processing for hyo-laryngeal kinematics is not fully understood. In 11 healthy adults, we examined changes in kinematics with sensory adaptation, sensitivity shifting, with oropharyngeal swallows vs. pharyngeal swallows (no oral processing), and with various bolus volumes and tastes. Only pharyngeal swallows showed sensory adaptation (gradual changes in kinematics with repeated exposure to the same bolus). Conversely, only oropharyngeal swallows distinguished volume differences, whereas pharyngeal swallows did not. No taste effects were observed for either swallow type. The hyo-laryngeal kinematics were very similar between oropharyngeal swallows and pharyngeal swallows with a comparable bolus. Sensitivity shifting (changing sensory threshold for a small bolus when it immediately follows several very large boluses) was not observed in pharyngeal or oropharyngeal swallowing. These findings indicate that once oral sensory processing has set a motor program for a specific kind of bolus (i.e., 5 ml water), hyo-laryngeal movements are already highly standardized and optimized, showing no shifting or adaptation regardless of repeated exposure (sensory adaptation) or previous sensory experiences (sensitivity shifting). Also, the oral cavity is highly specialized for differentiating certain properties of a bolus (volume) that might require a specific motor plan to ensure swallowing safety, whereas the pharyngeal cavity does not make the same distinctions. Pharyngeal sensory processing might not be able to adjust motor plans created by the oral cavity once the swallow has already been triggered.

Effects of submental neuromuscular electrical stimulation on pharyngeal pressure generation

OBJECTIVE

To investigate the immediate and late effects of submental event-related neuromuscular electrical stimulation (NMES) on pharyngeal pressure generation during noneffortful and effortful saliva swallows.

DESIGN

Before-after trial.

SETTING

Swallowing rehabilitation research laboratory.

PARTICIPANTS

Sex-matched (N=20) healthy research volunteers.

INTERVENTIONS

Participants received 80Hz NMES of 4-second duration to floor of mouth muscles that was time-locked to 60 volitional saliva swallows.

MAIN OUTCOME MEASURES

Manometry measures of peak pressures and duration of pressure events in the oropharynx, hypopharynx, and the upper esophageal sphincter (UES) were derived during execution of noneffortful and effortful saliva swallows. Measures were taken at baseline, during stimulation, and at 5-, 30-, and 60-minutes poststimulation.

RESULTS

Baseline pharyngeal and UES pressures did not differ between stimulated and nonstimulated swallows. At 5- and 30-minutes poststimulation, peak pressure decreased at the hypopharyngeal and at the UES sensor during noneffortful swallows. The effect lasted up to an hour only in the hypopharynx. No changes in duration of pressure events were observed.

CONCLUSIONS

Using this treatment paradigm, decreased peak amplitude in the hypopharynx up to an hour after treatment indicates a potential risk of decreased bolus flow associated with NMES. On the other hand, decreased UES relaxation pressure may facilitate bolus transit into the esophagus.

The effect of surface electrical stimulation on swallowing in dysphagic Parkinson patients

Surface electrical stimulation has been applied on a large scale to treat oropharyngeal dysphagia. Patients suffering from oropharyngeal dysphagia in the presence of Parkinson's disease have been treated with surface electrical stimulation. Because of controversial reports on this treatment, a pilot study was set up. This study describes the effects of a single session of surface electrical stimulation using different electrode positions in ten patients with idiopathic Parkinson's disease (median Hoehn and Yahr score: II) and oropharyngeal dysphagia compared to ten age- and gender-matched healthy control subjects during videofluoroscopy of swallowing. Three different electrode positions were applied in random order per subject. For each electrode position, the electrical current was respectively turned "on" and "off" in random order. Temporal, spatial, and visuoperceptual variables were scored by experienced raters who were blinded to the group, electrode position, and status (on/off) of the electrical current. Interrater and interrater reliabilities were calculated. Only a few significant effects of a single session of surface electrical stimulation using different electrode positions in dysphagic Parkinson patients could be observed in this study. Furthermore, significant results for temporal and spatial variables were found regardless of the status of the electrical current in both groups suggesting placebo effects. Following adjustment for electrical current status as well as electrode positions (both not significant, P > 0.05) in the statistical model, significant group differences between Parkinson patients and healthy control subjects emerged. Further studies are necessary to evaluate the potential therapeutic effect and mechanism of electrical stimulation in dysphagic patients with Parkinson's disease.