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Oral
Pharyngeal Dysphagia
Application of EMG
Biofeedback in the Treatment
of Oral Pharyngeal Dysphagia
Maggie Lee Huckabee, M.A.,
CCC/SLP
Senior Speech Language Pathologist
Dysphagia Specialist Massachusetts General Hospital Boston,
MA
Introduction
Oral-pharyngeal dysphagia is a common sequelae to a
variety of acute and chronic illnesses, including
cerebrovascular accident(16), traumatic brain injury(9),
oral-pharyngeal carcinoma(2) and a myriad of degenerative
neuromuscular diseases(5). Swallowing impairment can result
in significantly delayed recovery, malnutrition and
dehydration(14), pulmonary complications leading to
aspiration pneumonia and potentially death(3). Common
deficits include weakness in the musculature of the lips,
mouth, tongue, palate, pharynx and esophagus, incoordination
of movements, surgical ablation of tissue and decreased
sensation of the oral and pharyngeal cavities leading to a
delay in the stimulation of the swallow(11). In the past 5-10
years, there has been a significant movement toward
rehabilitative treatment of dysphagia. Dysphagia intervention
is utilized to both compensate for oral-pharyngeal swallowing
impairment and to change the physiology of the swallow
through muscle retraining, thus resulting in long term
improvement in swallowing(11). Many of the identified
treatment strategies require that the patient translate a
previously automatic physiological function into a
volitionally controlled, altered motor response. For many
patients, both those with and without associated cognitive
impairment, grasping the concept of altering swallowing
behavior is a challenge. There is little cognitive awareness
as to how a swallow is executed. The swallowing therapist is
consequently often confronted with confusion, frustration and
an inability of the patient to participate in his or her own
treatment. EMG biofeedback presents auditory and visual
signals to aid the patient in learning and practicing
dysphagia intervention exercises(4). The EMG signal
translates the previously automatic response into a concrete
representation of oral-pharyngeal movement. Viewing the
swallow as it occurs allows the patient to consciously
monitor and alter swallowing behavior. The patient is able to
clearly visualize the effects of specific compensatory and
therapeutic strategies and target visible, realistically
attainable goals. Additionally, in times of restrictions by
third-party payers, EMG biofeedback provides quantitative
data to document patient progress with treatment.
Treatment
Protocol
Treatment of oral-pharyngeal swallowing impairment relies
on accurate diagnosis. Thus any treatment protocol should be
preceded by a thorough diagnostic evaluation by a qualified
speech language pathologist. Specific exercises for the
treatment of neurophysiological deficits have been described
in the dysphagia literature(1,10,11). The scope of this
protocol does not include an exhaustive description of
dysphagic abnormalities and the associated treatment
strategies of choice. It will encompass description of those
treatment strategies that are appreciably enhanced by
biofeedback monitoring.
Using
MyoDac 2TM / MyoCompTM
The MyoComp System, as well as other computer assisted EMG
Biofeedback Systems, allows for long-term storage of patient
biographical, insurance and medical information on a separate
diskette. This is accessed through the database mode on the
main menu. In addition, a progress note section enables the
therapist to store session information regarding the nature
of treatment provided, the patients response to treatment,
and other pertinent information. This information can be
added to the diskette before or after a session through the
monitoring mode on the main menu.
Setting on MyoDac 2TM
Gain Setting at x10 for a reading from 0-100
uV.
Setting on MyoCompTM System
- Options-as desired for auditory feedback and visual
contrast of EMG line on background.
Monitor
- For two channel tasks, use Channel 1 Top, Channel 2
Bottom.
- For one channel tasks, use Channel 1 Center.
- Time-as desired. A setting of 15 seconds provides
more responsive input to patients in the early stages
of treatment.
Single Channel Monitoring
Oral
Motor Facial Exercises
In cases of unilateral cerebrovascular accident or
surgical resection and scarring from oral-pharyngeal
carcinoma, facial weakness and asymmetry may inhibit adequate
bolus control during feeding. Oral motor/facial exercises may
be used to improve function in weakened muscles or to reduce
constriction associated with scarring. Two muscles have been
targeted for retraining with biofeedback. The orbicularis
oris is a circular-appearing muscle that extends posteriorly
from the buccinator muscle, with upper and lower muscle
fibers inserting into the upper and lower lip. This muscle is
functionally responsible in the deglutitive process for
maintenance of the bolus within the oral cavity. The
buccinator muscle is a flat band of muscle that provides the
framework for the cheek. This muscle attaches at the
pterygomandibular raphe with insertion into the orbicularis oris. The
buccinator, combined secondarily with the masseter
muscle, serves to tighten the cheeks during mastication and
swallowing, inhibiting buccal pocketing. When the goal of
treatment is to increase symmetry of contraction of the
orbicularis oris and buccinator muscles, as in the case of
unilateral cerebral infarcts, biofeedback can be used to
assist the patient in matching the weakened musculature to
the stronger intact side.
Electrode Placement: The EMG sensors are attached with
surface single electrodes, connected to the MyoScan(TM)
sensor with electrode extender leads. As functional-facial
symmetry is the goal, two channels are used for the patient
to target function of weakened hemiparetic side to parallel
function of the stronger functioning side. The active
electrodes are placed over the orbicularis oris or buccinator
muscle with the ground electrode placed anterior to the
muscle (figure 1 and 2). For work on lip closure, the
function of both the upper and lower lip can be targeted;
however, the upper lip is more accessible for secure
electrode placement.

When targeting increased lip strength and closure, the
patient is instructed to repetitively purse their lips then
relax (figure 3). When targeting increased buccal tension,
patients are instructed to tighten the cheeks against the
teeth then relax (figure 4). Modeling of the task is usually
required. With each contraction of orbicularis oris or the
buccinator muscles and surrounding musculature, the patient
will see a slope in the receiving, feedback line. The
hemiparetic side will demonstrate decreased visual feedback
(figures 3a, 3b and 4a, 4b). The goal for treatment is to
shape the hemiparetic side to match the stronger, intact side
of the face. Intermittent tactile stimulation may be applied
by the therapist to increase sensitivity and response between
volitional exercise.

Pharyngeal Phase Exercises
Electrode Placement: One triode surface electrode is
placed vertically under the chin. The two active electrodes
are aligned centrally, spaced evenly between the inferior tip
of the mandible and the thyroid cartilage (figure 5).
Palpation is required for accurate placement.
Figure 5
Modified Valsalva / Effortful Swallows
A common diagnostic finding in the dysphagic population is
decreased or weakened contraction of the pharyngeal
constrictors responsible for propulsion of the bolus through
the pharynx. Weakness of these muscles results in
post-swallow pharyngeal residual of the bolus, placing the
patient at risk for post swallow aspiration. A modified
valsalva swallow, or hard swallow can be used as a
compensatory strategy to aid pharyngeal clearing during a
meal and also as an indirect exercise for increasing
pharyngeal constriction. The superior, middle and inferior
constrictors are internal pharyngeal muscles that are not
easily accessible by surface electrode. Direct EMG
measurement of these muscles is not feasible. Although
further investigation is required to specifically document
the correlation, clinical practice demonstrates a functional
relationship between increased pharyngeal constriction and
contraction of the submandibular musculature. Thus, in
focusing treatment on increased pharyngeal contraction, the
electrodes are placed to target the suprahyoid musculature.
This muscle group specifically includes the anterior belly of
digastric muscle, the stylohyoid muscle, and the mylohyoid
muscle. Collectively, these muscles are responsible primarily
for elevation of the larynx and tongue and anterior
displacement of the cricoid, hyoid, larynx, trachea and
tongue. The stylohyoid adds a component of posterior
displacement of the above structures with obliteration of the oropharynx.
The patient should initially be educated clearly as to the
nature of swallowing impairment and the goals of
intervention. The therapist demonstrates the technique on his
or herself with biofeedback monitoring in place. After
electrodes are placed on the patient, he or she is then asked
to attempt the strategy by swallowing hard and tightening the
muscles in the neck and shoulders during the swallow. The
patient is cued to produce high EMG peaks of short duration
on the video monitor (figure 6). The treatment objective is
production of increasingly higher readings. A quota for
expected increase is set for each treatment session. Changes
in readings are graphed to document progress.
Mendelsohn Maneuver
The superior point of entry into the esophagus is marked
by the cricopharyngeal sphincter muscle (upper esophageal
sphincter). In normal swallowing, this sphincter muscle
remains tightly closed until the occurrence of the swallow.
Vagus nerve innervation and laryngeal elevation jointly
contribute to a momentary opening of the cricopharyngeal
sphincter, allowing the bolus to leave the pharynx and enter
the esophagus. In the case of a dysphagic patient, this
muscle is impaired in its ability to maintain adequate width
or duration of opening. This results in post-swallow
pharyngeal residual, particularly in the pyriform sinuses.
Additionally, prolonged increased pressure of the
cricopharyngeal sphincter may contribute to the development
of a Zenkers diverticulum immediately inferior to the muscle.
The Mendelsohn Maneuver is a treatment strategy designed to
facilitate cricopharyngeal sphincter opening. This strategy
requires that the patient volitionally increase and maintain
laryngeal elevation, thus stretching the cricopharyngeal
sphincter. Since laryngeal elevation is the targeted
movement, the muscles monitored are the same as those
targeted for modified valsalva swallows, as mentioned above.
This muscle group would specifically include the anterior
belly of digastric muscle, the stylohyoid muscle and the
mylohyoid muscle.
As with the modified valsalva swallow, the patient should
initially receive a thorough explanation and demonstration of
the treatment strategy. After electrode placement, the
patient is instructed to identify the height of laryngeal
elevation during the swallow and hold that position for
several seconds before releasing muscular control and
completing the swallowing cycle. The biofeedback line will
shape boxes when the strategy is completed accurately (figure
7). The feedback line elevates off baseline with laryngeal
elevation for initiation of the swallow, is maintained off
the line while holding laryngeal elevation, then returns to
the baseline with completion of the swallow. Treatment
objectives include progressively increasing both the
amplitude of the reading and the duration of elevation of the
feedback line off baseline.
Relaxation of Pharyngeal Musculature
Several degenerative neuromuscular diseases result in
dysphagic symptoms that require relaxation of pharyngeal
musculature. In particular, Parkinsons Disease frequently
results in a poorly coordinated, hyper-reactive response of
pharyngeal contraction. A patient with this type of diagnosis
may demonstrate adequate strength of contraction, but
attempts to initiate the swallow results in a characteristic
groping behavior. The patient may attempt laryngeal elevation
for the swallow numerous times before actual onset and
completion of the swallow. Thus, when a swallow is ultimately
initiated, the effect is a weakened effort secondary to
previously expended energy (figure 8). The result is an
inefficient swallow with an increased risk for post swallow
pharyngeal residual and malnutrition secondary to fatigue. In
this case the muscles targeted are those responsible for
laryngeal elevation (the suprahyoid muscle group). The target
behavior is relaxation, rather than contraction, except
during the occurrence of the swallow.
The objective of relaxing the pharyngeal musculature
before and after the occurrence of a swallow is explained to
the patient. After surface electrodes are applied, the
patient is instructed to relax the muscles in the neck and
throat until the biofeedback line is flat. The patient is
then cued to swallow. The target behavior is a flat feedback
line with a single peak for the swallow.
Conclusion
Several other authors have investigated the utilization of
EMG in dysphagia diagnosis(6,7,8,12,13,15). These studies
consist primarily of the application of subcutaneous needle
electrode myography in the diagnosis of dysphagia and the
scientific documentation of normal swallowing behavior.
Further research in these areas is essential to the
development of refined protocols for EMG applications.
Subcutaneous electrode placement is generally not feasible or
recommended for daily clinical practice; however, these
studies can provide valuable information for the practicing
clinician in refining surface electrode EMG biofeedback.
EMG biofeedback holds great potential as an adjunct to
standard therapy for the rehabilitation of the dysphagic
patient when under the direction of a speech language
pathologist with expertise in this area. Biofeedback provides
several critical elements that are unavailable with standard
dysphagia therapy. Video monitoring allows the patient to
view the swallow as it occurs, converting a previously
automatic skill of which there is generally little awareness
to a visually represented task that can be consciously
monitored and altered. Target behavior and goal
identification is measurable, providing the patient with
invaluable insight into progress and motivation for continued
treatment. And finally, quantitative data are produced to
document the patients progress, facilitating reimbursement
from third party payers. Swallowing therapy techniques are
used to effect a change in the physiology of the oral and
pharyngeal swallow. Biofeedback, if used appropriately, is a
valuable patient aid in visualizing and documenting these
changes.
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Copyright, 1997
The
Biofeedback Foundation of Europe
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