**1. Introduction**

Dysphagia is a symptom related to swallowing disorders that impede or hamper safe, efficient, and comfortable oral ingestion [1], characterized by the abnormality in the transference of bolus from the mouth to the stomach [2]. In addition to compromising the swallowing process, dysphagia may impair overall health, the nutritional status, and lung conditions, impacting quality of life as well [3, 4].

There are many neurological diseases that can affect the neural structures which control the complicated mechanisms of oropharyngeal swallowing. Most symptoms and complications from neurogenic dysphagia are due to sensory-motor change of the oral and pharyngeal phases of swallowing [5]. In adults and in the elderly population, dysphagia often derives from stroke [6].

Different proposals for the rehabilitation of oropharyngeal dysphagia have been researched over the years. Thus, literature review studies demonstrate the effectiveness of using protective and facilitating swallowing maneuvers, showing physiological changes in specific aspects of swallowing in normal subjects increasing or decreasing the pharyngeal contraction, the lingual pressure, the upper esophageal sphincter relaxation and contraction, according to the different techniques [7] and in the rehabilitation of oropharyngeal dysphagia reducing or eliminating aspiration and improving functional outcomes in specific populations [8, 9].

Orofacial myofunctional exercises are a therapeutic approach for the treatment of oropharyngeal dysphagia [10]. In poststroke individuals, tongue isometric exercises result in an increase in tongue force, with an associated improvement in swallowing pressure, airway protection, and tongue volume in acute or chronic phases [11].

In a late poststroke case, these tongue exercises were associated with improved bolus control and increased oral intake [12]. The use of surface electromyography (SEM) as a therapeutic biofeedback is a resource described in various areas of health, with studies showing clinical efficacy for a variety of neuromuscular disorders. The electromyographic biofeedback can be used to aid in muscle relaxation, coordination, and/or muscle response pattern training, as well as increased recruitment of motor units during muscular activity.

The McNeill Dysphagia Therapy Program (MDTP), which improves the timing of physiological events during swallowing, is another rehabilitation modality for patients presented with neurogenic dysphagia. Following MDTP, subjects presented with chronic dysphagia showed temporal coordination of swallowing components close to that of healthy individuals, thus suggesting a normalization of swallowing timing [13].

As a therapeutic strategy aimed at the rehabilitation of oropharyngeal dysphagias, the electromyographic biofeedback [14] provides improved strength in swallowing and its coordination, understood as the best muscle recruitment during the function, associated with the attention and performance of cortical functions, simultaneously [15, 16]. Its use has been described in cases of dysphagia due to stroke [17–20], as well as in cases of patients with sequelae from the treatment of head and neck cancer [19], with improvement in swallowing and consequent increase in the oral intake of patients treated with biofeedback associated with conventional therapy.

Neuromuscular electrical stimulation (NMES) is another therapeutic approach used in the rehabilitation of oropharyngeal dysphagia (NMES). NMES has been recommended as an adjunctive modality to improve the results of exercises based on dysphagia therapy. According to Wijting and Freed [21], NMES is the application of electrical current pulses to the skin to stimulate muscle contraction by peripheral motor nerves. The electric current causes a depolarization of the peripheral motor nerve, usually where the nerve enters the motor end plate, which, in turn, will elicit muscle contraction.

NMES has drawn the attention of speech therapists since the initial application for dysphagia by Freed et al. [22]. Some studies have shown improvement in swallowing physiology [22–24] and quality of life [25] after using NMES in individuals presenting with oropharyngeal dysphagia and also, specifically, in poststroke patients [26–28]. The increase in laryngeal excursion has been described as a

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swallowing [45].

*Neuromuscular Electrical Stimulation and Electromyographic Biofeedback as Adjunctive…*

increase in the elevation of the larynx during swallowing [31].

physiological change in swallowing following NMES, related to the lowering of the hyoid bone during rest, in patients with neurogenic dysphagia [29, 30], and to the

In studies reporting higher level of oral intake [31, 32], decreased severity of dysphagia in patients with moderate dysphagia [33], increased sensitivity in poststroke individuals [34], and decreased laryngotracheal aspiration [31] were found as well. On the other hand, some studies found no difference in the clinical outcomes of patients undergoing rehabilitation with NMES, as compared to con-

In view of the possibility of using technological resources in the diagnosis and treatment of oropharyngeal dysphagia, this chapter presents the theoretical and procedural frameworks aimed at the application of EMG biofeedback and NMES as supporting methods in the treatment of oropharyngeal dysphagia, in cases affected

Regarding the effect of NMEE on swallowing, there is not a uniform stimulation protocol in terms of duration, number of sessions, and parameters of the electric current. Some studies show positive results of NMES in the treatment of dysphagia, but others suggest negative effects on hyolaryngeal elevation or do not find differences with respect to conventional therapy. It is known that NMEE can directly modulate swallowing and interfere with the mechanisms of central control and execution. In addition, the closure of the vocal folds during swallowing and speech

Additionally, the physiological responses obtained by NMEE can also be influenced by age and level of stimulation. A study [38] found interactions between age and stimulation amplitude on lingual and pharyngeal functions during swallowing. The anterior tongue pressure was reduced by motor stimulation in both age groups; however, the posterior lingual-palatal pressures were selectively reduced in adults. The base of tongue (BOT) pressures were increased by sensory stimulation in the elderly but decreased in young adults. Hypopharyngeal pressures were increased in both groups by motor stimulation. Therefore, age and NMEE level should be taken into account when planning the rehabilitation of

Specifically on the effectiveness of the application of NMES in poststroke dysphagia patients, several methods are proposed for NMES application, including level of stimulation, electrode placement, tasks requested during NMES, and frequency and duration of sessions. Aiming at understanding how the research has been conducted, **Table 1** presents the information on the studies that included

Studies with patients suffering from stroke who used the sensory level of stimulation showed improvement in swallowing function and that the increase in the sensorial input to the cortex can reduce swallowing problems. The thyrohyoid muscle stimulation was used in most studies, using motor stimulation to increase

Stimulation of the thyrohyoid muscle was used in most studies, using motor stimulation to increase the elevation of the larynx. Most studies show positive effects of NMES in the performance of swallowing in patients presented with poststroke dysphagia, especially when the stimulus is applied at the sensory level or when the level of motor stimulation is applied to the infrahyoid muscles, during

*DOI: http://dx.doi.org/10.5772/intechopen.84942*

**2. Neuromuscular electrostimulation**

is modified by NMES, owing to weakness and paresis [37].

ventional therapy [35, 36].

swallowing disorders.

the elevation of the larynx.

poststroke individuals, in their samples.

by stroke.

#### *Neuromuscular Electrical Stimulation and Electromyographic Biofeedback as Adjunctive… DOI: http://dx.doi.org/10.5772/intechopen.84942*

physiological change in swallowing following NMES, related to the lowering of the hyoid bone during rest, in patients with neurogenic dysphagia [29, 30], and to the increase in the elevation of the larynx during swallowing [31].

In studies reporting higher level of oral intake [31, 32], decreased severity of dysphagia in patients with moderate dysphagia [33], increased sensitivity in poststroke individuals [34], and decreased laryngotracheal aspiration [31] were found as well. On the other hand, some studies found no difference in the clinical outcomes of patients undergoing rehabilitation with NMES, as compared to conventional therapy [35, 36].

In view of the possibility of using technological resources in the diagnosis and treatment of oropharyngeal dysphagia, this chapter presents the theoretical and procedural frameworks aimed at the application of EMG biofeedback and NMES as supporting methods in the treatment of oropharyngeal dysphagia, in cases affected by stroke.
