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Braz J Oral Sci. July/September 2004 - Vol. 3 - Number 10
Electromyography: applied in the
phonoaudiology clinic
Miriam Nagae¹
Fausto Berzin²
¹Language therapist, State University of
Campinas
²DDS, PhD, Professor of Piracicaba Dental
School, State University of Campinas
Abstract
The aim of this study was to discuss the utilization of surface elec-
tromyography in the practice of phonoaudiology to obtain a picture
of the muscular compromise that occurs in patients with dental and
skeletal alterations. The behavior of muscles in functions such as
swallowing, chewing and respiration, and at rest, and possible devia-
tions thereof, will be examined by electromyography based on the
activated muscular chains. Compromises such as tension, flaccidity,
palsy and rhythm could be detected quantitatively and qualitatively
during the functions.
Received for publication: February 10, 2004
Accepted: April 28, 2004
Key Words:
eletromyography, language therapist, TMD
Correspondence to:
Mirian Nagae
Universidade de Campinas- FOP/UNICAMP
Departamento de Morfologia
Av. Limeira, 901
Cep:13.414-903, Piracicaba- São Paulo- Brazil
Phone: +55 011 30321102
e-mail: mnagae@uol.com.br
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Braz J Oral Sci. 3(10): 506-509 Electromyography: applied in the phonoaudiology clinic
Introduction
Phonoaudiology covers a vast area of clinical interests,
among them oral motricity, which is basically at the center of
impairments of muscle order. Knowledge of the condition of
the musculature is of utmost importance in these cases. The
tools that have been utilized to date for the handling of these
cases are: palpation, visual inspection and the opinion of a
professional. However, such an examination is rather
subjective in character.
With advances in technology, a series of instruments have
permitted a clearer and more objective view of the actual
condition of the musculature. In the phonoaudiology clinic,
electromyography, which records the electrical properties of
muscles, has thereby been a valued tool
1
. To perform an
electromyographic study, a professional needs a prior
technical understanding in the handling of instruments as
well as a profound knowledge of the anatomy and physiology
of the musculature to be investigated.
The choice of musculature would depend on the situation
and the interest of the examiner. In phonoaudiology, the
major focus is in the region of the head, chest and face
(muscles: temporal , masseter, suprahyoid group, mentual,
and labial orbicular).
The examination could help in the diagnostics, treatment
and even the prognostics of cases. Regarding its diagnostic
value, it would be possible to determine for individual as well
as groups of muscles both normal patterns and possible imbalances
found in the musculature, such as in the following cases.
of the suprahyoid muscle group during normal deglutition of
saliva.
Ave mV
Suprahyoid (right) 15.5
Suprahyoid (left) 17.3
Masseter (right) 4.5
Masseter (left) 3.9
Fig. 2 -
Electromyographic recording of the masseter muscle and
of the suprahyoid muscle group in a patient with interposition
of the tongue between the arches. Note the excessive action of the
masseter muscle.
Ave m V
Suprahyoid (right) 36.7
Suprahyoid (left) 30.3
Masseter (right) 8.6
Masseter (left) 13.2
b) In the mouth breather, we can observe that due to the
flaccidity caused by the mouth open, the labial orbicular
musculature needs to recruit many motor units to be able
to maintain the lip seal (figure 4). It is interesting to see
that after the patient is able to make nose breathing
automatic and/or after myotherapeutic intervention, the
muscles re-establish their normal pattern in the resting
state (figure 3).
Electromyography registration
a) During deglutition (figure1), the signal of the suprahyoid
muscle group is captured, which allows for a better
visualization of the moment of deglutition, because of it very
near to the musculature of the tongue. In cases of atypical
deglutition, the anterior interposition of the tongue between
the arches is common. This condition is found for example in
subjects with an anterior open bite (Angle´s Class II/1
rd
division), where the masseter muscle exerts an intense
pressure concomitant with the action of the suprahyoid
muscle group (figure 2).
Fig. 1-
Electromyographic recording of the masseter
muscle and
Fig. 3
-Electromyographic recording of the upper labial orbicu-
lar, mentual and masseter muscles in nose-breathing patients at
rest.
Ave mV
Upper labial orbicular 2.1
Mentual 1.3
Masseter (right) 1.6
Masseter (left) 1.8
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Braz J Oral Sci. 3(10): 506-509 Electromyography: applied in the phonoaudiology clinic
Fig. 4
- Electromyographic recording of the lower labial
orbicular, mentual and masseter muscles in mouth-breathing
patients Note the hyperactivity of thelabial orbicular and mentual
muscles at the end of maintaining a lip seal.
Fig. 6
-
Electromyographic recording of the masseter, mentual and
upper labial orbicular muscles, during mastication of bread, in
patients with anterior open bite (Angle´s Class II/ 2
rd
). Note the
excessive action of the upper labial orbicular and mentual muscles.
Ave m
V
Lower labial orbicular 3.8
Mentual 7.2
Masseter (right) 1.7
Masseter (left) 2.7
AvemV
Masseter (right) 97.7
Masseter (left) 80.3
Mentual 71.6
Upper labial orbicular upper 54.5
c) During mastication, there is a significant action of the
elevating muscles of the mandible, mainly the masseter
muscle and little involvement of the perioral muscles
(figure 5). When there is some alteration at the skeletal
level, in Angle´s Class II/2
rd
cases for example, we can see
that the musculature also undergoes a change in its pattern
of activation, as can be observed in figure 6, where the
mentual and labial orbicular muscles become significantly
active.
Regarding treatment, electromyography can be used to monitor
development, but also as a therapeutic tool via biofeedback
2
,
where patients learn to control their own neuromuscular
responses. This resource is very interesting mainly in relapse
cases after orthognathic surgery or orthodontic treatment,
which could be caused by a muscular memory
3
that does not
permit a new pattern of muscle behavior to be established. In
cases where there is pain or excessive tension in the
mastication muscles produced by parafunction, the capability
of monitoring the muscles is also very interesting.
In relation to prognostics, electromyography permits us to
determine the intensity of impairments (figure 7) and to obtain
at the end of treatment quantitative evidence of the modifications
that occurred (figure 8). Usually, an evaluation based on size
and sensitivity of the musculature is not always possible.
Fig. 5
–Electromyographic recording of the lower and upper
labial orbicular and masseter muscles,during mastication of
bread, in patients without any impairments.
Ave mV
Lower labial orbicular 14.3
Upper labial orbicular 15.9
Masseter (right) 52.4
Masseter (left) 33.5
Fig. 7
-Electromyographic recording of the anterior temporal and masseter
muscles, during mastication of bread. Note the disharmony in the action of
the masseter muscle and the general hypoactivity of the musculature.
Ave mV
Anterior temporal (right) 26.0
Anterior temporal (left) 35.1
Masseter (right) 26.1
Masseter (left) 63.5
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Braz J Oral Sci. 3(10): 506-509 Electromyography: applied in the phonoaudiology clinic
Currently, we are going through a very interesting phase,
because due to better access to technology and
interdisciplinary exchange of professionals such as
physiotherapists, dentists and clinicians, we are getting closer
to a sophistication that soon will permit us to see the various
physiological modifications occurring in musculature, using
such tests as electromyography.
Figure 8- Electromyographic recording of the anterior temporal
and masseter muscles during mastication of bread. Note the re-
establishment of equilibrium in muscular action in relation to that
in figure 7.
Ave mV
Anterior temporal (right) 25.6
Anterior temporal (left) 64.3
Masseter (right) 50.0
Masseter (left) 120.8
References
1. Dorland. Dicionário médico. 25.ed. São Paulo: Roca; 1997.
2. Basmajian JV, De Luca CJ. Muscle alive
:
their functions realed
by electromyography. 5
nd
ed. Baltimore: Willians & Welkins;
1985. p.385-90.
3. Erhart EA. Neuroanatomia. 6.ed. São Paulo: Roca; 1986. p.235.
4. Knutson MMML, Soderberg GL, Ballantyne BT, Clarke WR. A
study of various normalization procedures for within day EMG
data. J Electromyogr Kinesiol 1994; 4: 47-59.
5. Portney L. EMG and examinations about conductions nervous
velocity. In: O’Sullivan SB, Schimitz, TJ. Fisioterapia: avaliação
e tratamento. 2
nd
ed. São Paulo: Manole; 1993. Cap.10.
6. Silvério KCA. Avaliação vocal e atividade eletrica dos musculos
supra-hioideos e esternocleidomastoideo em individuos com
desordem temporomandibular miogenica em situações de repouso
e fonação [thesis]
.
Piracicaba: FOP/UNICAMP; 2002.
Phonoaudiology is capable of carrying out electromyography
at least for the purpose of investigating the potential action
of motor units by means of electrodes placed on the skin
surface.
In the phonoaudiology clinic, the electromyographic
interpretation is performed by means of a raw signal, which
permits us to visualize qualitatively the size and shape of
muscle action potentials.
When there is an interest developed by more specific
situations or for research, there is a need for prior handling
of the signal, termed normalization
4
, for the purpose of
obtaining a common language to be able to compare results.
Electromyographic kinesiology is the procedure most
indicated in such cases, since it allows us to study muscular
activity for both individual and groups of muscles in various
conditions, and to obtain a quantitative evaluation of the
signal
5
. In phonoaudiology investigations, this has been
achieved following this methodology
6
. In the
phonoaudiology clinic, implementing the normalization of
the signal in the future is inevitable. However, it is import to
remember that this type of methodology is only intended for
the quantitative investigation of isolated aspects (fatigue,
stress, amplitude), and it is not sufficient for a more globalized
evaluation necessary for the clinic. The raw signal in this
aspect provides us with a more qualitative view, where
nuances in shape, size and time of the recordings could
furnish revealing information for a better understanding of
cases.
The ability to perform electromyographs in the clinic on a
daily basis improved significantly the quality of all aspects,
mainly with regard to the understanding of the causes of the
imbalances encountered that will inevitably produce more
rapid and accurate results.
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