1. No category

Neuromuscular Electrical Stimulation of the Muscles
Surrounding the Shoulder
Lucinda L Baker and Karen Parker
PHYS THER. 1986; 66:1930-1937.
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Neuromuscular Electrical Stimulation of the Muscles
Surrounding the Shoulder
LUCINDA L. BAKER
and KAREN PARKER
Neuromuscular electrical stimulation (NMES) can be used to augment range-ofmotion, strengthening, and facilitation treatment programs of the muscles surrounding the shoulder. The purposes of this article are 1) to describe the uses of
NMES around the shoulder joint as developed through our clinical use and 2) to
detail the effects of an NMES program on chronic shoulder subluxation as
determined by a clinical study. Because of the complexities of this multiarticular
joint, NMES is most useful in the initial phase of the ROM, and stimulated
contractions are compromised, relatively, as the humerus moves above the 90degree horizontal plane. The use of NMES to provide scapular stabilization often
entails unwanted alteration of the pressures on the spinal column, occasionally
making the treatment program unusable. Electrical stimulation to prevent or
correct shoulder subluxation, especially in the neurologically involved patient,
provides the therapist with a powerful new treatment technique. In a group of
stroke patients, shoulder subluxation was reduced significantly (p < .05) at the
completion of a six-week NMES program. Some of the problems, and possible
solutions, unique to the development of electrical stimulation programs for the
shoulder muscles are discussed.
Key Words: Electric stimulation, Physical therapy, Shoulder dislocation, Shoulder
joint.
Neuromuscular electrical stimulation
(NMES), in recent years, has been well
established as an effective adjunct to
range-of-motion, strengthening, facilitation, and spasticity management programs used by the physical therapist.1
The efficacy of NMES in such programs
for the shoulder muscles is compromised somewhat, however, because of
the large number of muscles surrounding the shoulder joint and the complex
synergistic relationships among muscles. The shoulder complex is one of the
most intricate joint complexes of the
body, creating articular surfaces between three bones and allowing movement in three planes. Although Peat
discusses the specific anatomic and kinesiologic characteristics of this joint
complex (see the article by M. C. Peat
in this issue), practical application can
be demonstrated in the development of
Lucinda Baker is Assistant Professor, Department of Physical Therapy, University of Southern
California, 12933 Erickson, Downey, CA 90242
(USA), and Consulting Neurophysiologist for the
Rancho Los Amigos Rehabilitation Engineering
Center, Downey, CA 90242.
Karen Parker is Physical Therapy Supervisor I,
Rancho Los Amigos Medical Center, Downey, CA
90242.
This research was supported in part by National
Institute of Handicapped Research Grants
G008200045 and G008300077.
treatment programs that include NMES
for the shoulder. The purposes of this
article are 1) to describe several electrical
stimulation programs that we have
found useful in our clinical practice and
2) to detail the effects of one of these
programs as determined through a clinical study.
GENERAL SHOULDER
STIMULATION
Guidelines
Electrical stimulation can be used to
assist in gaining the initial degrees of
motion for patients with frozen shoulder
or shoulder-hand syndrome. Because of
the limitations in stimulating the muscles around the shoulder and difficulties
in restoring the normal synchronization
of these muscles, treatment programs
including NMES generally are restricted
to the initial phase of the ROM. Electrical stimulation programs are less effective than other types of treatment programs when the range increases above
the 90-degree horizontal plane. Because
of the repetitive nature of cyclical stimulation, however, many patients who
have shoulder pain prefer electrically
stimulated ROM to other methods of
increasing ROM. The repetitive nature
of NMES, in combination with its analgesic effects similar to those of transcutaneous electrical nerve stimulation,
provides the therapist with a tool to
achieve ROM increases in many patients who are less tolerant of traditional
ROM programs. A cyclical stimulation
treatment program provides regular and
consistent motion in a set range, allowing the patient to relax during the treatment session. The relaxed patient, thus,
may achieve increases in ROM by
avoiding the "splinting" of muscles that
occurs so often during traditional ROM
procedures.
In the development of shoulder stimulation programs, electrodes must be cut
and shaped individually, depending on
the size of the patient. Custom electrode
sizes will ensure specific activation of
the desired muscles without overlap to
other muscle groups. Other factors to
consider in developing NMES programs
include avoiding stimulation over bony
prominences and avoiding placing electrodes too closely together. Both monopolar electrode configurations, with the
active negative electrode smaller than
the positive electrode, and bipolar electrode configurations, with electrodes of
equal size both placed in a single targeted muscle area, are appropriate in
PHYSICAL THERAPY
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shoulder stimulation programs. In addition, stimulation with symmetrical triphasic waveforms, usually combined
with bipolar electrode placements, often
is perceived by the patient as being more
comfortable2 than stimulation with a
compensated monophasic waveform.
The increased comfort probably is attributable to the relatively large size of
the muscles being activated around the
shoulder. A symmetrical biphasic waveform has been shown in other large muscle groups to reduce the amount of amplitude needed to achieve a Fair plus
stimulated muscle contraction.2 This reduced current intensity decreases the
amount of superficial sensory activation, often making the patient much
more comfortable and, thus, more willing to comply with the treatment program.
Shoulder Flexion-Abduction
Because electrical stimulation generally is limited to one or two muscle
groups, stimulation of muscles to
achieve shoulder flexion or abduction
beyond the 90-degree horizontal plane
is especially difficult. Flexion and abduction to the horizontal plane usually
can be achieved by using single-channel
electrical stimulation of the deltoid muscles. Placing the active electrode from a
stimulator using a compensated monophasic waveform over the anterior deltoid muscle will enhance the shoulder
flexion response, whereas placing the
active electrode over the middle deltoid
muscle will enhance the shoulder abduction response. When a bipolar electrode configuration is used with a biphasic waveform, both electrodes are
placed over the deltoid muscle group
(Fig. 1). Thus, with either waveform
used, the effect of NMES is neither
purelyflexionnor abduction but, rather,
a combination of both.
Electrical stimulation of the deltoid
muscles alone generally will not yield
shoulder flexion or abduction beyond
90 degrees. Scapular rotation is a component of shoulder motion in the initial
stages of flexion and abduction, but its
importance becomes apparent as the
shoulder moves beyond 90-degree horizontal plane (see the article by M. C.
Peat in this issue). Dual-channel stimulation providing activation of the anterior and middle deltoid muscles and
some of the muscles around the scapula
can provide additional muscle power to
achieve ROM above the horizontal
plane in many individuals. To achieve
Fig. 1. A. Electrode placement to achieve a combined flexion-abduction motion of the humerus
to approximately 90 degrees. Electrodes should be cut to fit the subject and to maintain a
minimum of 2.5 cm (1 in) of space between the electrodes. Because of the size of this subject,
large electrodes provide optimal comfort and increased recruitment of the muscle and still meet
the above criteria. The bipolar configuration can be used with either compensated monophasic
or symmetrical biphasic waveforms, although the latter waveform may be more comfortable for
the patient. B. Radiograph of the stimulated humeral motion using the electrode placement
shown in A and with a biphasic waveform.
shoulder motion beyond 90 degrees horizontal, the first channel of stimulation
generally is set to activate the anterior
and middle deltoid muscles. A brief rise
time and rapid contraction of these
muscles generally is used. A second
channel of stimulation, with a longer
rise time, may be used to activate portions of the rotator cuff muscles located
near the lateral border of the scapula.
An alternate placement of the second
channel of stimulation is just off the
medial border of the scapula, allowing
activation of the downward rotators of
the scapula to stabilize that portion of
the shoulder complex (Fig. 2). With
some dual-channel NMES devices, both
active electrodes can be connected to a
common indifferent electrode, usually
placed over the middle deltoid muscle
(Fig. 2). Some dual-channel NMES devices, however, provide the stimulus
pulse simultaneously to both channels.
Patients may complain of discomfort
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range is the goal, however, two-channel
stimulation may assist in achieving that
goal.
Isolated Flexion or Abduction
Fig. 2. A. Dual-channel, three-electrode placement to achieve a combined flexion-abduction
motion of the humerus above the 90-degree horizontal plane. The active electrodes are placed
over the subject's anterior deltoid muscle and just off the medial border of the scapula to
provide some scapular stabilization. Both active electrodes are connected to the common
indifferent electrode positioned over the middle deltoid muscle. For this dual-channel electrode
placement, the compensated monophasic waveform is preferred most often. B. Radiograph of
the stimulated humeral motion using the electrode placement shown in A.
under the common indifferent electrode
because the current of both channels is
reaching that electrode at the same time,
effectively doubling the current density.
The three-electrode, dual-channel configuration sometimes is preferred because of the small surface area available
for the placement of electrodes.
The dual-channel stimulated contraction rarely establishes normal synchronization between the scapula and the
glenohumeral joint, but it does provide
a means of achieving ROM above the
horizontal plane. Because the stimu-
lated motion does not approximate the
normal functioning of the complex glenohumeral joint, stimulation within this
range should be used with caution.
Pathological conditions of the glenohumeral joint must be considered, because
the potential for impingement syndromes exists. Because of the abnormal
relationship produced between the stimulated scapular and humeral movements, dual-channel NMES probably
would not be the treatment of choice for
a muscle facilitation or reeducation program. When motion to the terminal
Electrical stimulation can be used to
activate and isolateflexionor abduction
of the glenohumeral joint by using
monopolar electrode placements and a
compensated monophasic waveform.
The monopolar electrode configuration
includes an active electrode over the
anterior deltoid muscle for isolated
shoulderflexionor over the middle deltoid muscle for isolated shoulder abduction. The active electrode then is connected to a larger indifferent electrode,
usually placed just medial to the border
of the scapula. Because of the difference
in the size of the electrodes and the use
of a compensated monophasic stimulation waveform, the majority of the neuromuscular activation occurs under the
negative (ie, active) electrode. Shoulder
flexion or abduction to 90 degrees horizontal can be achieved with these
monopolar electrode configurations.
Isolatedflexionor abduction beyond 90
degrees horizontal is more difficult to
achieve, even if a second channel of
stimulation is instituted
Stimulation of pure flexion or pure
abduction may be desirable for the patient who is recovering from traumatic
subluxation of the humerus or from a
rotator cuff tear.3,4 In our experience,
most patients with other types of shoulder involvement benefit from the combined flexion-abduction program and
do not require the isolated flexion or
isolated abduction treatment program.
Because of the combined monophasic
waveform and monopolar electrode
configuration, isolatedflexionor abduction stimulation generally requires
higher current levels to achieve the desired quality of muscle contraction. This
increased current demand may cause
the patient secondary sensory intolerance to the stimulation. A careful training period of three to five days is
desirable for all shoulder stimulation
programs, but it may be critical to the
success of NMES programs isolating
specific muscle around the shoulder.
Shoulder Extension
Electrical stimulation of the posterior
deltoid muscle generally is restricted to
orthopedic patients requiring discrete
posterior deltoid muscle strengthening4,5
or to specific applications in the patient
with spinal cord injury. Surgical transfer
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of the posterior deltoid muscle to the
triceps tendon is a procedure that often
is performed to provide the patient with
C6-level quadriplegia with active elbow
extension.6 After the patient has received the physician's approval to perform active exercises, electrical stimulation is used to facilitate voluntary
control of the posterior deltoid muscle
with subsequent elbow extension. This
facilitation program for elbow extension
is brief and often superseded by a voluntary exercise program using electromyographic feedback. When the surgical transfer is determined to be well
established, usually after one to three
months of healing time, electrical stimulation to increase the strength and
power output of the posterior deltoid
muscle can be used to augment traditional muscle strengthening programs.
Scapular Muscle Stimulation
Stimulation of the muscles surrounding the scapula for the purpose of stabilization during other joint movements
may be desirable. Although activation
of the middle trapezius and rhomboid
muscles may achieve a degree of scapular adduction, winging of the scapula
generally is not resolved without stimulation of the serratus anterior muscle.
The patient demonstrating serratus anterior muscle weakness and secondary
scapular winging can use electrical stimulation for facilitation under special
conditions, such as when a scapula has
separated from the rib cage sufficiently
so that an electrode can be placed over
the ventral aspect of the bony scapular
surface (Fig. 3). A second, indifferent
electrode may be placed on the lower
lateral side of the trunk (Fig. 3). With
the active electrode under the winged
scapula and the second electrode over
the broad area of the serratus anterior
muscle's origin, stimulation can provide
adequate realignment of the scapula to
correct its winged posture. As the patient
gains strength in the serratus anterior
muscle and the winging of the scapula
becomes less pronounced, placement of
the active electrode becomes increasingly difficult. After the scapula is repositioned appropriately on the trunk
and no longer wings, achieving further
realignment of the scapula with electrical stimulation may be difficult or even
impossible. We have been unsuccessful
in activating the serratus anterior muscle unless we can position the active
electrode over the ventral surface of the
scapula. The largest patient population
to benefit from this stimulation of the
Fig. 3. A. Electrode placement used to activate the weak serratus anterior muscle. The active
electrode is placed over the ventral surface of the scapula, and the larger inactive electrode is
placed over the general area of the serratus anterior muscle's origin. B. Stimulated contraction
demonstrating the scapular realignment attained with the electrode placement shown in A. The
active electrode is more visible during the stimulated contraction.
serratus anterior muscle is the group
with quadriplegia or quadriparesis. Patients with posterior thoracic nerve palsy
and subsequent serratus anterior muscle
denervation, however, generally will not
tolerate this electrode configuration.
Stimulation over bony prominences
generally is uncomfortable, especially
when pulse durations adequate to activate denervated muscle directly are
used.
Electrical stimulation of the muscles
surrounding the scapula must be administered with great care, especially in very
young or very old patients. Neuromus-
cular contractions in the trunk can lead
to alterations of the pressures on the
spinous processes and spinal bodies.7 In
very young, immature patients, these
pressures potentially may lead to shortterm, acute spinal deformities.7 If electrodes are placed unilaterally around
one scapula, lateral deformities, or scoliosis, may result from strong neuromuscular activation.7 If the electrodes
are placed bilaterally around both scapulae, reduction of the normal thoracic
kyphosis7 and subsequent increase in
the pressures on the posterior spinal elements can occur. Although electrical
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stimulation can be used to manage
certain types of idiopathic spinal deformities,8,9 under chronic stimulation
conditions NMES potentially may contribute to spinal deformities if used inappropriately.
In the adult, these same types of pressures occur on bony and soft tissues.
The spinal column in an adult largely is
immobile, however, and pressures on
the spinal column may result in pain
and discomfort associated with soft tissue distraction, potential pinching of
nerve roots, and possibly even the presence of stress fractures of the spinous
processes or bodies.7 Special care must
be taken with older adults, especially
postmenopausal women, who frequently demonstrate a high degree of
osteopetrosis, often in the spinal processes and bodies.10-12 Although these
complications occur less commonly in
the young adult, the use of Fair plus
stimulated muscle contractions around
the spinal column and the potential
complications of such a treatment program should be considered during the
development of NMES-assisted scapular
facilitation programs.
Shoulder Subluxation
Inferior subluxation of the glenohumeral joint is a common complication
of both neurologic13-18 and musculoskeletal injuries.3-5 Although subluxation may occur after acute trauma, the
incidence of chronic subluxation is low
in the orthopedic patient population.3-5
In the patient with neurologic involvement, especially the patient with stroke
or head injury, chronic subluxation of
the shoulder is a frequent problem. Lack
of normal muscle activity after an acute
insult to the central nervous system is a
major contributing factor to the incidence of subluxation. Reduced muscle
activity can lead to stretching of the
shoulder capsule, which is critical to the
maintenance of glenohumeral joint stability.19,20 If the shoulder capsule has
been stretched, subluxation often will
persist, regardless of whether the patient
develops voluntary control or even spasticity in the muscles around the shoulder. Subluxation in patients with stroke
has been associated with increased pain,
with increased incidence of inappropriate autonomic responses in the upper
extremity,21 and occasionally with traction damage to the brachial plexus and
other peripheral nerves.22 In the patient
with neurologic impairment, therefore,
joint-capsule stretching should be
avoided. Although the early use of sling
support of the glenohumeral joint has
been thought to reduce this problem,
the persistently high incidence of
chronic subluxation18 indicates that the
use of slings may be inadequate in controlling the effects of gravity on the
shoulder joint. When subluxation has
begun already, use of the sling may retard further joint separation, but generally it is incapable of reducing the existing subluxation. Electrical stimulation
for the reduction of shoulder subluxation not only may prevent further joint
separation, but also can provide normal
glenohumeral alignment for the patient
when assuming the upright position.
Thus, maintaining normal joint alignment and counteracting the stretching
of the shoulder capsule that is caused by
gravity are advantages of such stimulation. To assess the effectiveness of an
electrical stimulation program in the
management of shoulder subluxation,
we conducted a study in which we compared the effectiveness of conventional
slings to that of NMES.
Study Method
Sixty-three patients admitted to the
Stroke Service at Rancho Los Amigos
Medical Center were evaluated prospectively for this study. To qualify for the
study, all subjects were required to demonstrate a minimum of 5 mm of shoulder subluxation in their involved upper
extremity, as compared with radiographs of their uninvolved extremity.
This bilateral comparison was made to
eliminate the variability of joint laxity
from one individual to the next. All
radiographs were taken with both upper
extremities dependent at the patient's
side23,24 and depicted both of the patient's shoulders.
Patients were assigned randomly to
one of two groups. The Control Group
used conventional "hemi-slings" or
wheelchair arm supports when they
were in the sitting or standing position.
We administered NMES to the patients
assigned to the Study Group for an initial five-day training period. Stimulation
of the posterior deltoid and supraspinatus muscles was used to reduce shoulder
subluxation. Because stimulation of the
supraspinatus muscle with the active
electrode also activated the upper trapezius muscle, resulting in shoulder
shrugging, the active electrode was
placed over the posterior deltoid muscle
(Fig. 4). Stimulation frequency was set
to create a tetanized muscle contraction
for each patient and varied between 12
and 25 pulses per second. A compen-
sated monophasic waveform was used
to minimize the unwanted shoulder
shrugging. During the training program,
the patients' treatment sessions were
changed gradually from three half-hour
sessions to a single six-to-seven-hour cyclical stimulation session with a 1:3 ONOFF ratio. To protect the joint during
this nonaggressive training program, the
patients used a hemi-sling or wheelchair
support between and during the treatment sessions.
When a patient was able to complete
a six- to seven-hour period of stimulation without marked fatigue of the stimulated muscle groups, we increased the
ratio of ON time to OFF time of subsequent treatment sessions in a stepwise
fashion. The patients, thus, received
NMES treatments of increasing aggressiveness during the next five weeks of
the study. Increases in stimulation tolerance were attained by lengthening the
ON time by two-second intervals every
one or two days. When the stimulator
reached the maximum ON time available (24 seconds), we decreased the OFF
time by two-second increments every
one or two days. Patients were assessed
daily for muscle fatigue as indicated by
a lack of full stimulated reduction of the
subluxation, which was estimated by
manual palpation. Patients who demonstrated full stimulated reduction
throughout the six- to seven-hour treatment period for one or two days then
progressed to the next step of the ON;
OFF ratio. The maximal ON-OFF ratió
allowed by the stimulator was 24:2. This
electrical stimulation program was conductedfivedays weekly for a total of six
weeks. Twenty patients each from the
Control and Study groups were assessed
for the effect of the shoulder subluxation
on their perceived pain at the shoulder.
This assessment was based on the patients' subjective reports to nursing and
physical therapy staff members and on
the patients' requests for analgesic drugs.
Assessment radiographs showing both
involved and uninvolved shoulders were
taken at the end of the six weeks. Study
Group patients received no NMES
treatments during the 24-hour period
before their final radiograph. This restriction was imposed to eliminate the
short-term effects of facilitation potentially created by the NMES treatments.
Each radiograph was assessed by two
independent observers, one of whom
was unaware of the patient's status in
the study (ie, Control or Study). A twoway analysis of variance with a repeated
measures design was used with Tukey's
1934
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Fig. 4. A. Electrode placement used to reduce shoulder subluxation. The active electrode is placed over the posterior deltoid
muscle to minimize the amount of shoulder
shrugging. (Note the specialized electrode
configuration, designed to optimize activation
of the supraspinatus muscle and minimize
stimulation over the spine of the scapula.) B.
Radiograph of a patient with hemiparesis
demonstrating marked shoulder subluxation.
C. Radiograph of the same patient shown in
B with the stimulated subluxation reduction.
post hoc technique to identify significant
differences in the measured subluxation.
The significance level was set at .05.
Study Results
Thirty-two Control Group and 31
Study Group patients were assessed in
the subluxation program. Pertinent patient data are summarized in the Table.
The means of shoulder subluxation recorded before the treatment program
were 14.8 mm for the Study Group and
13.3 mm for the Control Group. At the
termination of the six-week study period, the mean subluxation of the Study
Group was 8.6 mm and that of the
Control Group was 13.3 mm (Fig. 5).
Although subluxation in the Control
and Study groups was similar at the
inception of the study, we found a statistically significant difference at the end
of the study. This difference was attributed to a significant decrease in the
amount of shoulder subluxation in the
TABLE
Comparison of Control and Study Group Patient Data
Control
Study
Age
(yr)
Time Since
Onset (d)
Group
46
49
s
Range
51
32
(14-258)
(17-122)
55
56
Study Group patients, as compared with
no change in the subluxation of the
Control Group patients. At the termination of the six-week assessment period, 3 of the 32 Control Group patients
demonstrated reduction of subluxation
to less than 5 mm. Ten of the 31 Study
Group patients showed similar reduction after the assessment period. Threemonth follow-up radiographs from 11
Control Group and 13 Study Group
patients demonstrated no change in the
Control Group subjects and a mean
1- to 2-mm loss of the subluxation reduction achieved in the Study Group
patients.
In the 40 patients assessed for pain
during the six-week study period, we
identified no direct relationship between
the degree of subluxation and the
Side of
Involvement
Sex
s
Range
M
F
Right
Left
12
13
(27-69)
(29-74)
13
18
19
13
14
15
18
16
amount of perceived pain at the shoulder joint. We also did not identify any
significant reduction of perceived pain
in those patients who demonstrated considerable decreases in shoulder subluxation. Two Study Group patients expressed discomfort at the shoulder joint
that appeared to be related directly to
the electrical stimulation. We suspended
the treatment sessions for both patients
for several days until their pain ceased.
They then resumed the treatments with
no further episodes of pain associated
with the electrical stimulation of the
shoulder joint.
DISCUSSION
Shoulder subluxation has been reported in 50% to 75% of the patients
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Fig. 5. Means, standard error of the means, and ranges of shoulder subluxation measured
before and after the six-week assessment period for both the Control and Study groups.
Statistical differences were found between the Control and Study groups after the six-week
treatment period and between the pretreatment and posttreatment measurements in the Study
Group patients.
who have experienced a cerebral vascular accident.13-18 Although the correlation between the degree of shoulder subluxation and pain currently does not
appear to be established fully, the potential exists for neural structural damage
in the patient with severe subluxation.21,22 In addition, a subluxated shoulder does not provide a stable base from
which to develop or increase upper extremity control.17 Andersen has suggested that, if stretching of the joint
capsule could be avoided during the
acute and flaccid phases of neural recov-
ery, many patients would develop sufficient muscular activity to maintain the
glenohumeral joint in normal alignment
after the recovery phase.17 This avoidance of capsular stretching subsequently
would reduce the incidence of chronic
subluxation in patients with stroke and
potentially reduce the number of individuals experiencing pain or autonomic
dysfunction in the hemiparetic upper
extremity.13-18,21 Although early use of
conventional slings may provide adequate protection for some patients with
subluxation, slings are largely ineffective
in restoring and maintaining normal
joint alignment. Thus, reestablishing
and maintaining glenohumeral joint
alignment is one way in which NMES
may be superior to the conventional
sling. Although many of the patients in
our study used a conventional sling on
admission to the medical center, they
nevertheless exhibited substantial subluxation at the inception of the stimulation treatment program. The significant reduction of subluxation in our
Study Group patients indicates that
NMES provided a greater degree of protection for the joint than did the traditional sling and arm supports. We believe that, if the stimulation treatments
had been administered earlier in the patients' recovery process, the degree of
subluxation would have been reduced
further. After the joint capsule has been
stretched, however, muscle contraction
can substitute only partially for the normally passive capsular structures. Early
prophylactic use of NMES may provide
adequate protection to minimize or prevent further capsular stretch, the secondary chronic subluxation of the hemiparetic shoulder, and its undesirable sequelae.
Most patients who received NMES
were unable to attain full reduction of
the subluxation after the six-week program. This failure to attain full reduction may have resulted because of the
degree of subluxation present at the beginning of the NMES program. Patients
treated prophylactically with an "NMES
sling" during the acute phase of recovery
from CNS damage may demonstrate reduced chronic subluxation even though
voluntary muscle control may be minimal. Because the Rancho Los Amigos
Medical Center is a rehabilitation facility and does not admit patients during
the acute flaccid stage of recovery, further research on the effectiveness of the
NMES sling during this phase of recovery is needed and must be conducted in
an acute care setting.
Two alternative treatment options exist for patients with chronic subluxation.
The first is the use of a conventional
sling to maintain the reduced degree of
subluxation achieved by the completion
of the NMES program. A second alternative would be the use of long-term
electrical stimulation as an orthotic assist to maintain the normal alignment
and integrity of the glenohumeral joint.
This latter approach to chronic subluxation treatment may be especially attractive to the younger patient because
most slings are undesirable cosmetically.
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An additional advantage of a long-term
NMES program is the relatively normal
alignment of the shoulder joint that is
maintained. This normal alignment of
the shoulder complex creates a stable
platform from which the patient may be
able to develop more usable distal motor
control. The disadvantages of the
chronic use of NMES include the problems associated with long-term use of
surface electrical stimulation. Proper
electrode placement is difficult for most
patients with hemiparesis to achieve and
maintain by themselves. In addition,
skin irritation from electrodes, gels, and
tape frequently occurs with the longterm use of surface electrical stimulation. Although a variety of electrodes
are available, many patients with hemiparesis find long-term care of the skin
over the supraspinatus and posterior
deltoid muscles difficult to maintain.
We have found that chronic use of
NMES for shoulder subluxation management has been most successful for
patients in supervised care settings
where supportive individuals can assist
the patient in maintaining appropriate
electrode placement and skin care. We
do not use long-term NMES programs
for subluxation management routinely,
largely because of these technical difficulties.
The chronic use of NMES for the
reduction of shoulder subluxation may
become more feasible when implanted
or semi-implanted electrode systems become available. Epimysial electrodes
may be inserted with minor local surgical procedures and, when connected
to a stimulation system, may provide
reliable, reproducible electrical stimulation results. With the development of
fully implanted electrode systems, stimulation may become a preferred treatment for the patient demonstrating
chronic shoulder subluxation because of
CNS dysfunction. The stimulation treatment program is not so much an alternative to the traditional sling but a treatment technique that can provide the
patient with more normal musculoskeletal alignment that can result in improved function.
CONCLUSION
Neuromuscular electrical stimulation
of the muscles surrounding the shoulder
joint is an effective method of early
mobilization, especially for the patient
experiencing shoulder pain. Because of
the complexities of the shoulder joint
articulations, however, NMES is not
recommended for gaining terminal degrees of the ROM. The use of NMES
for the reduction of shoulder subluxation, especially in the patient with neurologic involvement, can provide not
only an alternative to cumbersome
sling-type assistive devices but also a
normal musculoskeletal base from
which the patient can use both proximal
and distal control. The primary advantage of NMES may be its prophylactic
use, before stretching the shoulder
capsule, to maintain joint integrity
throughout the flaccid period of neurologic recovery. For the patient whose
chronic subluxation is not reduced fully
during a six- to eight-week therapeutic
stimulation program, long-term application of NMES may be an effective
alternative to the use of the traditional
sling support. Until implanted electrode
systems become available, however,
long-term use of surface electrical stimulation can be managed by only a few
patients with hemiparesis and their families.
Acknowledgments. We thank C.
Criswell, J. Weiss, D. Menenger, J. Jackson, and C. Zablotny for their assistance
in the collection of the shoulder subluxation data. We also thank E. R. Gardner
for her assistance in content editing and
J. Scofield and P. Robb for their assistance in manuscript preparation.
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Volume 66 / Number 12, December 1986
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1937
Neuromuscular Electrical Stimulation of the Muscles
Surrounding the Shoulder
Lucinda L Baker and Karen Parker
PHYS THER. 1986; 66:1930-1937.
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