Russell
C.
MD
FritZ,
Clyde
#{149}
Suprascapular Evaluation Entrapment
of the
nerve is frequently differential diagnosis
A. Helms,
with
suprascapular overlooked
in the
of shoulder
pain. The diagnosis is typically not considered until patients develop severe weakness secondary to atrophy of the spinatus (spinous) musculature that the nerve supplies. Twenty-seven masses were identified adjacent to the suprascapular nerve on magnetic resonance (MR) images of the shoulder; there were 21 ganglion cysts, two synovial sarcomas, one Ewing sarcoma, one chondrosarcoma, one metastatic renal cell carcinoma, and one hematoma associated with a fracture. Atrophy of both the supraspinatus and infraspinatus muscles was seen in association with anteriorly located masses and proximal entrapment of the nerve in 11 cases
(40%);
isolated
atrophy
infraspinatus muscle was sociation with posteriorly masses nerve
of the
seen in aslocated
and distal entrapment of the in nine cases (33%). MR imag-
ing may facilitate the diagnosis of suprascapular nerve entrapment in patients with shoulder pain of unclear origin when perineural masses and atrophy of the spinatus musculahire are present. Index terms: Ganglion, 41.361 #{149}Nerves, MR. 41.1214 #{149} Sarcoma, 41.374 #{149} Shoulder, abnormalities, 41.31, 41.32, 41.374 #{149}Shoulder, MR. 41.1214
Radiology
1992;
182:437-444
MD
From
the
Department of Radiology, UniverSan Francisco. Received Norevision requested January 15, 1991; revision received August 13; accepted August 28. Address reprint requests to R.C.F., Marin Radiology Medical Group, 487 Green Glen Way, Mill Valley, CA 94941. C RSNA, 1992
S. Steinbach,
MD
Harry
K Genant,
#{149}
MD
Nerve Entrapment: MR Imaging’
S
on MR images of the shoulder. These cases were retrospectively collected over a penod of 12 months. Nine of the patients were studied at our institution, two were discovered by us during overreading of
pain is a common probtern among patients seeking medical attention. Correct diagnosis and therapy may be difficult due to the broad list of disorders that may HOULDER
cause
this
symptom;
indeed,
diffemen-
tial considerations include rotator cuff and labmat tears, calcific tendinitis, bicipital tenosynovitis, gtenohumemat and acmomioctavicular joint arthritis and instability, subacromiat bursitis, adhesive capsulitis, and cervical radiculopathy. Magnetic resonance (MR) imaging of the shoulder is often performed in this group of patients when the diagnosis is uncertain (1-3). Although it is welt described in the literature (4-36), suprascapulam nerve entrapment has been regarded as a relatively uncommon condition that is easily overlooked in the differential diagnosis of shoulder discomfort. The suprascaputam nerve is a mixed motor and sensory nerve that carries pain fibers from the glenohumemat and acmomioctavicutar joints and provides motor supply to the supraspinatus and infraspinatus muscles (Fig i). Patients
with
trapment
suprascaputam
typically
specific
nerve
present
shoulder
pain.
with
25 asymptomatic
healthy
studied
for
to assess
masses
adjacent
nerve;
these
cruited
labrum
(mean,
was
symptomatic
shoulder
40 years).
The
study
group who to the
consisted
The
right
shoulder
symptomatic
the
in eight
left
cases.
The asymptomatic group consisted of 20 men and five women aged 22-56 years (mean, 36 years). The right shoulder was imaged
in 12 volunteers,
and
the left
shoulder was imaged in 13. MR imaging was performed system
(Signa;
waukee) face
with
GE Medical
with
a dedicated
coil anteriorly
ing two
patients MR
Mil-
shoulder
sur-
in alt of the volunteers were
system
America Catif)
by
a i.5-T
Systems,
and in 24 of the 26 patients.
cisco,
The remain-
imaged
(MT/S;
MRI, using
with
a
Diasonics
South
San
a 5-inch
Fran-
anterior
face coil. Oblique coronal, oblique axial images were obtained
sum-
sagittal,
and
in all cases. A variety of pulse sequences was used. At least one Ti-weighted spin-echo pulse se-
quence
(600-800/20-30
msec/echo case.
time
Either
[repetition
msec])
was
a T2-weighted
used
(1,800-2,000/20-60)
weighted
gradient-echo
angle)
sequence was
each case. At least one quence was performed
gradient-echo
tients
were
masses
pulse
or a T2*
pulse
30#{176} flip
in whom
time in each
spin-echo
sequence
(300-400/15-30,
may
used
in
se-
in 13 of the 27 paidentified.
Image thickness was 4-5 mm with or without a 1-mm intersection gap. Two images were usually obtained for the spin-echo and
four
images
were
of 26 sympto have nerve
cuff of 22 10-75
and
METHODS
were noted suprascapular
to eval-
subjects.
in 18 cases,
was
sequences,
tomatic patients mass adjacent
re-
of the rotator
in asymptomatic
years
Toshiba
tar nerve.
AND
been study
The symptomatic group consisted male and four female patients aged
non-
sity of California, vember 26, 1990;
PATIENTS
had
and
of
suprascapular
of a separate
the MR appearance
was
presence
to the
uate
15 cases and inclua group of
volunteers
the
volunteers
as part
0.35-T
Suprascaputam
noted at MR imaging that entrapment of the supmascapu-
outside cases, and the remaining were sent to us for consultation sion in this study. In addition,
en-
nerve entrapment is usually not considemed until profound weakness and denervation atrophy of the spinatus (spinous) musculature is apparent, resulting in prolonged disability. MR imaging, commonly performed in patients with shoulder pain of uncertain origin, may allow earlier recognition of suprascapulan nerve entrapment. In this article, we describe the appearance of clinically unsuspected gangtion cysts and other soft-tissue masses cause
I
Lynne
#{149}
a
Abbreviations: NCV = nerve
EMG
conduction
=
electromyography,
velocity.
obtained
for the gradient-echo 256
or 256
sequences.
x 192
16 cm2 field
matrix
of view.
dimeglumine
was
A 256 used
a
Gadopentetate
(Magnevist;
Berlex
Labora-
tories, Wayne, NJ) was intravenously ministered at a dose of 0.1 mmol/kg
Ti-weighted tients and
one
weighted
fat-saturation
was
were
in three
administered
dimeglumine of enhancement.
sequence six
patients
gadopentetate
sequence
have
de-
in the symptomatic follow-up MR stud-
of these patients had undergone 5 years earlier, but only
MR imaging report was asymptomatic cyst
was
of
been
(37).
Five of the patients group also underwent one
pulse of the
to improve the conspicuity The technical features
this fat-saturation scribed previously
ies;
adbefore
imaging in five of the paof the volunteers. A Ti-
performed
who
x
with
available for review. subject in whom
found
underwent
the
The one a ganglion
follow-up
im-
aging tetate
with administration of gadopendimeglumine 10 months after the
initial
study.
Each
case
was
assessed
skeletal radiologists following findings ence and location
by two
muscuto-
(R.C.F., C.A.H.) for the on MR images: presof a mass, size of the
mass, signal intensity T2-, or T2*weighted
of the images,
mass and
on Ti-, en-
hancement characteristics. The presence abnormal signal intensity or decreased bulk of either the supraspinatus or in-
of Figure
fraspinatus muscles was noted and the degree of muscular atrophy graded as mild, moderate, or severe. Fatty infiltra-
tion was characterized streaks
and defined
of increased
the affected
signal
muscle
by
intensity
within
on the Ti-weighted
images that decreased with T2 weighting. Increased water or “edema” within a muscle was characterized by signal intensity that was isointense with unaffected musdes
on
the
creased
Ti-weighted
images
on the T2-weighted
areas
of signal
teromedial noted
void
when
Clinical
of the
to the
glenoid
suits
were
was obtained
of the patients. Electromyography and nerve conduction velocity were
available
in nine
in all
(EMG) (NCV) repatients.
The
and
at EMG
of combined
infraspinatus
muscle
rophy,
whereas
fined
as isolated
tus
muscle
distal
atrophy
supmaspinatus
denervation
entrapment
tow-up ranged age, 7 months).
went
surgery.
symptoms
were
to impingement
than
due
identified gg
The
of a malignant
thought
tients underwent the preoperative
to be
resulting
nerve
two patients acromioplasty,
underwent and the
underwent
computed
on MR images
(presumed
armasses
gan-
exploration of a ganglion
for
nerve
en-
tomographic
(CT)-
guided
percutaneous
aspiration
pected caputar
ganglion cysts resulting in suprasnerve entrapment. One patient adjacent
entrap-
to
trapment on the basis of MR imaging and EMG findings. Three additional patients
treated
rather
paor bi-
of the pa-
in suprascaputar
nerve
secondary cuff
with
adjacent
Seven
surgical diagnosis
hematoma
of fol-
rotator
neoptasm
nerve.
de-
was
of the infraspina-
duration
shoulder
the
supraspinatus
of the suprascapular
not treated. Four surgical resection
the suprascapular
a posterior was
duration
noted,
and
as unchanged, asymptomatic.
from 2 to 25 months (averThirteen patients underIn two of these patients, the
to suprascapular
#{149} R2ilinInai
opsy
The
of the
ment; these throscopic
cysts) were underwent
with
alone.
to follow-up.
glion tients
at-
Twenty-five of the 26 patients were available for follow-up; one patient was lost
of the
nerve.
and
The
nerve
infraspinatus
passes
muscles
beneath
the supe-
nor transverse scapular ligament in the suprascapular notch, then runs deep to the supraspinatus muscle and the inferior transverse scapular ligament to pass through the spinoglenoid notch. The inset shows a ganglion cyst in the suprascapular notch causing entrapment of the nerve anteriorly and a ganglion cyst in the spinoglenoid notch causing entrapment of the nerve posteriorly. Anterior entrapment of the nerve will result in atrophy of both the supraspinatus and infraspinatus muscles, whereas posterior entrapment will result in selective atrophy of the infraspinatus muscle. Entrapment of the suprascapular nerve anywhere along its course is associated with deep, poorly localized shoulder pain. hg. = ligament.
cyst
location of the mass and the presence of atrophy on MR images were correlated with the EMG findings of either proximal or distal suprascaputar nerve entrapment. Proximal entrapment was defined as evidence
view
the course
Focal pos-
present.
correlation
Posterior
to reveal
in-
images.
adjacent
aspect
and
1.
sectioned
glenoid
rim
fracture
and
to the suprascapular with
follow-up
conditions
were
improved,
was classified
or completely
mass
ranging
in size
from
1 to 7 cm with a mean maximum diameter of 2.4 cm was noted in alt 26 patients and in one of the 25 votunteems.
A component
of the
creased
mass
27 cases;
signal
weighted
posterior
intensity
images
intensity images.
was
extension
nat intensity 5 mm
this
on
and
on the T2A focal area noted
finding
Ti-
signal
or T2*weighted of decreased
sig-
in size from
adjacent
was
noted
on the
ages
five
2 to
to the
pos-
of the glenoid notch in nine
prominent in the
the
seen de-
increased
ranging
was
sequences Atrophy was seen
RESULTS A definite
i2 of the
into the infraspinatus fossa was in six. All of the masses exhibited
tenomedial aspect the spinoglenoid
immobilization.
of clinical their
of sus-
present in the spinogtenoid notch of the scapula in 26 of these 27 cases. Extension of the mass anteriorly into the supraspinatus fossa was seen in
in cases;
to be more
gradient-echo
cases
im-
in which
these
were performed (Fig 2). of the supmaspinatus muscle in ii of the 27 cases (40%)
and was mild in five, moderate in two, and severe in four. Atrophy of the infraspinatus muscle was seen in 20 of the
in five,
27 cases
moderate
(74%)
and
was
in ii,
and
severe
I3Phri12ri
mild
in 1QQ.
I
Figure
2.
Ganglion
cyst
in the
spinoglenoid
notch resulting in suprascapular nerve entrapment. (a) Ti-weighted oblique coronal MR image (800/20) demonstrates a rounded 1.5-cm
a.
mass
with
low
signal
intensity
(arrow)
inferior to the posterior aspect of the supraspinatus muscle. (b) T2*weighted oblique coronal MR image (400/20, 30#{176} flip angle) shows increased signal intensity of the ganglion cyst (black arrow). Note focal area of decreased signal intensity along the inferolateral aspect of the cyst (white arrow). (c) Ti-weighted axial MR image (800/20) demonstrates a rounded mass with low signal intensity (arrow) just lateral to the distal suprascapular nerve. (d) Gradient-echo axial MR image (300/10, 90#{176} flip angle) shows the ganglion cyst (curved arrow) and focal area of low signal intensity within the cyst (straight arrow), likely representing cortical bone or hemosidenn. Roughening and irreg-
b.
ularity
of the
adjacent
surgery; however, were found within
intensity on
within
the
glenoid
no flecks the cyst.
the
was
found
of cortical
atrophic
T2-weighted
at
bone
muscles
images
was
noted
in five patients. Interestingly, in one of these patients the abnormal signal intensity within the infraspinatus muscle completely resolved and the spinoglenoid notch ganglion cyst spontaneously decreased in size from 3.0 to 0.8 cm;
d.
C.
four (Fig 3). Isolated atrophy of the infraspinatus muscle with sparing of the supraspinatus muscle was seen in nine of the 27 cases (33%). Isolated atrophy of the supraspinatus muscle with sparing of the infraspinatus muscle
was
not
seen
Increased signal ment, on swelling scapular
nerve
Ganglion
in our
intensity, of the was
not
patients.
enhancesupraidentified.
Cysts
Twenty-one onstrated MR
of the 27 masses findings
dem-
characteristic
marginated
with
homoge-
neous Ti and T2 prolongation. They were variably rounded, septated, or tubular. Alt 2i ganglion cysts were in men; ages ranged from 25 to 68 years (mean, 39 years). The cysts were tocated on the right side in 14 men and on the left side in seven. The one mass detected in the asymptomatic
seen,
subject
changed showed
at iO-month no evidence
Volume
182
#{149} Number
remained
un-
follow-up and of enhancement 2
and
this
dimegtumine atrophy has been
patient
has
remained
asymptomatic at 20-months followup. Interestingly, the four symptomatic patients with ganglion cysts and evidence of suprascapulam nerve entrapment who received gadopentetate dimeglumine had rim enhancement around the margins of the cyst (Fig 6). Etectmodiagnostic studies (EMG and NCV)
of a gangtion cyst (Figs 2-6). The ganglion cysts were all well defined and smoothly
with gadopentetate (Fig 4). No muscular
were
21 patients
performed with
in nine
ganglion
cysts
of the and
the results were positive for suprascapulam nerve entrapment in each of these cases. Atrophy was seen on MR images in three of the four cases in which the EMG indicated that the supraspinatus Atrophy was seven
of the
muscle seen on nine
cases
was abnormal. MR images in in which
the
EMG indicated that the infraspinatus muscle was abnormal. The overall correlation between MR imaging and EMG abnormalities was, therefore, 77% (iO of the 13 muscles with EMG evidence of denervation were abnormat on MR images). Increased signal
this
decrease
in size
and
resolution of infraspinatus edema was accompanied by resolution of pain and weakness in the 8-month interval between MR examinations. Proximal entrapment was suggested on the basis of both supraspinatus and infraspinatus muscle abnommalities at EMG in four of nine cases.
A ganglion
cyst
was
noted
ex-
tending anteriorly into the supraspinatus fossa in three of these four cases (75%) with EMG evidence of proximal entrapment (Figs 5, 6). Anterior extension of a ganglion cyst was seen in only one of five cases (20%) with EMG evidence of distal entrapment; of note, in this case, EMG was performed in the 3-month interval between MR examinations that demonstmated spontaneous rupture of this anteriorly extending cyst, perhaps accounting for the lack of an abnommat supraspinatus muscle on the EMG. A component of the ganglion cyst
was
seen
in the
spinoglenoid
notch in each of the nine cases in which the EMG indicated distal entrapment. Definite proof of the diagnosis was available in eight of the ganglion cysts,
six of which
had
EMG
evidence
of suprascaputam nerve entrapment. Five of these cysts were mesected at surgery, and the diagnosis was histologically
proved.
In addition,
Radiotov
three
#{149}
Figure
3. Ganglion cyst in the spinoglenoid notch resulting in isolated denervation of the infraspinatus muscle. (a) T2-weighted axial MR image (2,000/60) reveals a 1.0-cm mass with high signal intensity (arrow) adjacent to the distal
suprascapular
nerve.
Atrophy
and
increased signal intensity of the infraspinatus muscle (i) is also noted. (b-d) Sequential medial to lateral Ti-weighted oblique sagittal MR images (800/20) demonstrate the course of the suprascapular nerve (white arrows) beneath the supraspinatus muscle in the supraspinatus fossa (b), through the spinoglenoid notch (c), and beneath the infraspinatus muscle in the infraspinatus fossa (d). The ganglion cyst is seen laterally in the spinoglenoid notch (black arrow in d). A = acromion, C = coracoid process, S = supraspinatus muscle, i = infraspinatus muscle.
cysts ance,
were which
cyst
fluid.
a.
b.
aspirated with CT guidyielded typical viscous Each of these eight patients
presented with pain and weakness and was asymptomatic after treatment; the duration of follow-up ranged from 6 months). A presumptive
2 to i3 months
(average,
diagnosis
was
made
on the basis of imaging features EMG findings in the remaining ganglion
cysts.
In two
cases,
and i3
appearing ganglion cysts, each with EMG evidence of denervation atnophy, were explored and not identified at surgery. In one of these cases, the patient improved and the ganglion cyst was not apparent on follow-up
MR
images;
the
gangtion
cyst
likely
spontaneously ruptured pmeopematively on was lanced during surgical exposure. In the other case not identi-
fled
at surgery,
the
symptomatic
due
MR image
in the cyst; the not seen
to the
posterior means
patient
remained
postoperatively
follow-up change glion likely
and
showed
appearance gangtion at surgery
inability
the gan-
notch approach
conservatively. fraspinatus
they
were
Atrophy muscle was
with
the
MR
of the present
appearance
further patients.
MR
Other
Masses
or pursued
not
imaging
results.
Two
these scopic
patients underwent acrornioptasty and
arthrorepair
Soft-tissue
in these
of
on
of these
of the
spina-
MR images. EMG in these patients.
other
identified nerve
(four iO-68
females years). plasms were readily from the gangtion by noting adjacent
The
suprascapular
motor
and
nerve
sensory
is a mixed
nerve
that
is de-
(Ewing
than
and
gan-
adjacent in six pa-
to
and two males Malignant neodistinguished cysts on MR images bone destruction
sarcoma,
chon-
omohyoid
muscles
to enter
glenoid
notch,
passing
beneath
inferior at the spine.
transverse scapular lateral border of the In the supraspinatus gives off two motor branches supraspinatus muscle and sensory branches from the
the
ligament scapular fossa, it to the receives capsular
and
In the infraspinatus
fossa,
catty
in each of the five malignant masses. A definite fracture of the posterior glenoid rim was seen adjacent to a hematoma that extended
two
to the
tmaprnent
joint and scapula (5,ii). of the nerve anteriorly,
into
proximal
to the motor
proved
spinoglenoid
notch
in a 68-
the
supraspinatus fossa through the suprascapulam notch, passing beneath the superior transverse scapular tigament. The nerve then runs deep to the supraspinatus muscle to enter the infraspinatus fossa through the spino-
tient in this series who was administened gadopentetate dimegtumine (Fig 7). The diagnosis was pathologi-
the
was
DISCUSSION
three
drosarcoma, and metastatic renal cell carcinoma) and heterogeneous signal intensity and lobular contours in two cases (synoviosamcoma). Uniform enhancement was noted in the one pa-
of
8). Each
atrophy
nived from the upper trunk of the brachial plexus originating from the fourth, fifth, and sixth cervical nerve roots. It passes deep to the trapezius masses
cases
(Fig
had
muscles performed
tus
with
inin
of a
with
#{149} Radiology
studies
in
in one.
woman
entrapment
treated
EMG
cases,
440
EMG
three
year-old
six patients
other’s is unthe diagnosis
nerve
tients aged
ganglion cyst; treatment was directed to the rotator cuff in each of these variable
with
the
patients
to the ganglion cyst seen images had not been verified
that
In three cases, theme was evidence of rotator cuff disease in addition to a mass
secondary on MR
teams;
of these
of suprascaputar
glion cysts were the suprascapular
seen on cases in im-
being
both cases, and confirmatory evidence of distal suprascapulam nerve entrapment was present
tendon
of one
has improved and the changed. At follow-up,
case
by
performed. Spontaneous rupture was follow-up MR images in two which the patients’ conditions
while
supmaspinatus
condition
the
was
proved
small
no
of the cyst was in this
to visualize
spinoglenoid of the anterior
d.
C.
typical
ligarnentous shoulder and
tus
motor muscle
shoulder
structures acromioctavicutar
branches as
welt
as
of the joints.
off
it gives
infraspina-
filaments
branches February
to
the
En-
be1992
a.
b.
C.
Figure rounded
4.
30#{176} flip weighted evidence
angle) shows increased signal intensity of the ganglion cyst (arrow). axial MR image (800/20) obtained with fat suppression after intravenous of enhancement (arrow). This mass was identical in appearance to that
Ganglion
1.5-cm
cyst
mass
in the
(curved
spinoglenoid
arrow)
notch
just lateral
of an asymptomatic
to the distal
volunteer.
suprascapular
(a) Ti-weighted
nerve (straight H = humeral
axial
arrows). head, G
administration seen on an MR
=
MR
image
(b) T2*weighted glenoid, Sp
(800/20)
scapular spine. dimeglumine 10 months earlier.
a
the nerve is also ondary to a sling of fixation
thought
(400/20,
(c) Tishows
=
of gadopentetate image obtained
sites
demonstrates
axial MR image
no
to occur
sec-
effect at potential in the supmascaputam
notch and spinogtenoid notch (25,26). Compression of the suprascapulam nerve by a ganglion cyst has been described in 24 surgically proved cases;
with
24 of the
pain,
fraspinatus
presented
atrophy
muscle,
combined praspinatus des
24 patients
22 had
of the
and
four
atrophy of both and infraspinatus
(5,10,12,15,30,36).
a.
b.
Figure 5. Ganglion cyst in a patient with infraspinatus muscle atrophy. (a) Ti-weighted lar mass with low signal intensity extending
clinical
the supraspinatus
notch
(2,000/60)
Mark
fossa
shows
Forte,
Colorado
and
increased
MD, and Springs,
spinoglenoid signal
Luke
and EMG evidence of supraspinatus axial MR image (800/20) demonstrates along the length of the suprascapular
intensity
Cesaretti,
of the
MD, Department
muscle, wilt the supraspi-
natus
and
muscles.
infraspinatus
Dis-
tat entrapment of the nerve, within the spinogtenoid notch on the infraspinatus fossa, will result in selecof the
infraspinatus
mus-
cle. Entrapment of the suprascapular nerve anywhere along its course is usually associated with deep, poorly localized shoulder pain. Occasionally, as in one of our cases, there may be dramatic atrophy and weakness without pain in cases of documented entrapment (19,21). The clinical features and treatment of suprascaputan nerve entrapment have been welt described (4-36). To our knowledge, there have been 139 reported cases since the first description of this syndrome in 1959. The diagnosis is usually not considered Volume
182
cyst
axial MR image
(arrows).
of Radiology,
(Case
USAF
courtesy
Academy
of
Hospital,
#{149} Number
cyst mass
was discovered involved the
2
sumuscases,
positive, ganglion
at surgery. supmascutan
The notch
in four of the 24 cases, the supmaspinatus fossa in one, the spinogtenoid notch fossa
the
in i8, in one.
and the Ganglion
spinoglenoid
cases, extended supraspinatus
the supraspinatus in atrophy of both
atrophy
(b) T2-weighted
ganglion
Cob.)
neath result
tive
(arrows).
and a tubunerve in
the
In most
the findings at EMG were and a clinically unsuspected
in-
had
infmaspinatus cysts involved
notch
in alt of our
until the development of dramatic atrophy of the spinatus musculature after an average of i2 months of shoulder pain. Often it is the patient who first notices a concavity over the posterior scapula as a manifestation of severe infraspinatus muscle atro-
tended posteriorly into the infraspinatus fossa in four. To our knowledge, theme are no reports of suprascaputan nerve entrapment in the radiology literature, reflecting the previously limited mole of diagnostic imaging in the evatuation of these patients. Plain radio-
phy;
clinical
graphs
tory
of weakness,
examination
with
ings at EMG and studies diagnostic
is confirma-
positive
find-
nerve conduction of nerve entrap-
of causes
of injury
or en-
tnapment of the suprascaputar nerve have been described, including scapulam (9,33) and humemat (27) fractures, anterior shoulder dislocation (i7), penetrating or surgical trauma (34), compression by tumors (35), and anomalous or thickened superior (ii) or inferior (6,21,28) transverse scaputan ligaments.
Traction
on kinking
of
be useful
that
cysts have the posterior
ment. A variety
may
fractures prascaputar
21
anteriorly into the fossa in eight, and ex-
may nerve.
in detecting
damage Although
the
suganglion
been noted to arise from joint capsule in several
of our cases and in at least five of the reported cases, shoulder amthmogmaphy
has
not
demonstrated
filling
of
these cysts (ii,i4). CT also failed to depict a large recurrent gangtion cyst in one report in which it was performed (4). The preoperative detection of a mass causing suprascaputam nerve entrapment has been recently reported in three cases, however, by Radiology
#{149} 441
a.
b.
Figure
6.
MR image creased
Ganglion
cyst
(2,000/60)
shows
signal
septated
intensity
mass
with
suppression after S = supraspinatus
using sound
that
with
a tubular
are
high
seen
intensity
with the
anterior
administration
of CT and
cause
evidence
mass
throughout
signal
intravenous muscle.
a combination (36).
Masses
in a patient
C.
of severe
high
signal
infraspinatus
intensity
infraspinatus
muscle
to the supraspinatus
of gadopentetate
and
moderate
supraspinatus
muscle
atrophy.
(a) T2-weighted
extending along the floor of the supraspinatus fossa. Atrophy (i). (b) More superior T2-weighted axial MR image (2,000/60) muscle (s). (c) Ti-weighted axial MR image (600/20) obtained
dimeglumine
shows
enhancement
of the
rim
of this
ganglion
cyst
axial
and
in-
shows
a
with
fat
(arrows).
ultra-
supmascapular
nerve entrapment may now be welt localized and characterized with MR imaging, reflecting the superior softtissue
contrast
dition, atrophy viding
of this
modality.
In ad-
MR imaging may demonstrate of the spinatus muscles, proevidence of denervation sec-
ondary
to the
visualized
mass.
Gan-
glion cysts account for the majority of these masses and are typically homogeneous, have low signal intensity on Ti-weighted images and high signal intensity on T2-weighted images, and show rim enhancement with gadopentetate dimeglumine. While the diagnosis of suprascapulam nerve entrapment has traditionally been made with EMG and NCV studies,
MR
imaging
may
provide
(5,23).
MR
imaging
is corn-
monly performed in patients with shoulder pain of uncertain origin, whereas the specific diagnosis of neumat entrapment must be considered to perform an EMG study. Indeed, each of the 2i ganglion cysts noted in this series was not suspected and was not palpable.
clinically
A probable ganglion cyst was noted in the spinoglenoid notch of one of the 25 volunteers. Since a neural tumom such as a schwannoma could have a similar appearance, we brought this patient back to undergo follow-up imaging with administration of gadopenetate dimeglumine. The mass did not enhance, and this 442
Radiotogy
#{149}
b.
Figure 7. Synoviosarcoma adjacent to the suprascapular nerve. (a) Ti-weighted oblique coronal MR image (800/20) demonstrates a lobulated mass (arrows) and severe atrophy of the supraspinatus muscle. (b) Ti-weighted oblique coronal MR image (800/20) obtained after intravenous administration of gadopentetate dimeglumine shows uniform enhancement of the mass (arrows). Areas of low signal intensity within the mass corresponded to radiographically evident calcifications.
compte-
mentary anatomic information and allow earlier diagnosis of suprascaputar nerve entrapment. The hallmark of this diagnosis is pain followed by weakness and atrophy of the spinatus muscles
a.
subject
did
not
symptoms
develop
signs
of entrapment.
or
It seems
likely that a gangtion cyst, while capable of causing entrapment and not uncommon in this location, may not always be the cause of a patient’s shoulder pain. In this sense, many of these ganglion cysts may be anatogous
and
to disk
the
atic unless structures
protrusions
patients
may
in the
spine,
be asymptom-
mass effect develops.
on
the
neural
Spontaneous decompression of a ganglion cyst was noted in at least two patients in this series. Additionally, spontaneous rupture may have occurred in one of our cases in which the mass could not be found at sumgery
and
was
not
present
on
a post-
operative MR image. Given the nurnben of ganglion cysts we identified within i year with MR imaging and
the observation dramatically only speculate masses may
that decrease
these cysts may in size, one can
on how often have accounted
pmascaputam
nerve
was
conservatively.
treated
these for su-
entrapment
that Indeed,
a
recent report emphasized effective conservative therapy in four patients with EMG evidence of distal suprascapular nerve entrapment of unclear origin (22); perhaps some of these patients had ganglion cysts in the spinogtenoid notch that ruptured as in our patients. All 21 of our patients with gangtion cysts catty
were proved
male, as were all 24 surgicases described in the
literature (5,iO,12,i5,30,36). An association with weight lifting may partially account for this finding, as seven of our 2i cases occurred with weight lifters. Moreover, weight lifting has February
1992
lence tients
of rotator cuff with shoulder
cysts
should
source
not
be discounted
of symptoms
especially
Acknowledgments: The authors following people for contribution rial: John Barr, MD, Luke Cesaretti,
disease in papain. Ganglion
if atrophy
as the
in these
patients,
is present
on
drew Deutsch, MD, Mark Forte, MD, Malcolm Friedman, MD, Marc Goldberg, MD, Ned Grove, MD, Phoebe Kaplan, MD, Howard Lee, MD, Chaney Li, MD, Russell Low, MD, Richard Mitchell, MD, and Christian Neumann, MD.
MR
images. Minor degrees of increased signal intensity are commonly seen in the supraspinatus tendon and may not necessarily be the source of symptoms. EMG should be performed and
Extension glenoid
of the hematoma notch
was
noted
into
the spino-
on other
images.
glion cyst if evidence of suprascapular nerve entrapment is present. Surgical and conservative therapy have each been advocated in patients with supmascaputar nerve entrapment
2.
(5,19,22,23).
3.
4.
of MR imaging. Radiology 1989; 172:223229. Kopell HP, Thompson WAL. Pain and
directed
(iO,i2,30,36)
as well
in the with pmecysts
as in the
case
me-
ports of patients with EMG evidence of supmascapulam nerve entrapment treated conservatively (22,29). Also, an anatomic study has shown that distal suprascapulam nerve entrapment may predominate in men because of the differences in the spinoglenoid ligament. The spinogtenoid ligament was absent or rudimentary in 60% of women compared with 13% of men; also, the size of the spinoglenoid canal formed by the ligament was
more
variable
in men
(18).
Focal areas of tow signal intensity were noted in the spinoglenoid notch adjacent to nine of the ganglion cysts in our series. We believe this nepresents
a small
cause
of the
tensity
and
area
of cortical
dephasing
bone
of signal
“blooming”
that
be-
in-
was
present on gradient-echo images. Attemnatively, this tow signal intensity may
be due
to hemosiderin
or catcifi-
of an abnormal spinoglenoid ligament. A clean explanation for this finding was not found at surgery in each case; however, roughening of the posterior glenoid was noted in one of our cases (Fig 2), suggesting a traumatic origin. Ganglion cysts were seen in association with abnormalities of the rotator cuff in three patients. This has also been described previously (8,20,31) and is not surprising given the prevacation
Vnliimo
ig,
#{149} MIlniliDr
“
toward
Surgical
the
therapy
1.
has
earlier
diagnosis
and
con-
summary,
entrapment relatively easily
suprascaputar
has been uncommon
overlooked
regarded condition
of shoulder
diagnosis
is usually
as a that
discomfort. not
weights.
experience, was
advent
On
the
we believe
likely
underdiagnosed
of MR
imaging.
6.
8.
9.
10.
ii.
12.
13.
is
The
14. 15.
considered
until profound weakness and denervation atrophy of the spinatus musculatrine are apparent, resulting in prolonged disability. MR imaging may allow early recognition of suprascapulan nerve entrapment secondary to clinically unsuspected masses. Ganglion cysts account for the majority of the masses causing entrapment and seem to occur exclusively in men, often in association with a history of lifting
5.
7.
differential
basis
of our
this
syndrome before
#{149}
the
cuff tears:
the frozen
nerve
in the
diagnosis
Rotator
proper
therapy allows for prompt alleviation of the pain associated with entrapment and better prognosis for the meturn of motor function (5,23). In addition, MR imaging can help identify and localize a mass preopematively, obviating the need for an exploratory surgical procedure in such cases. Furthermore, characteristic MR imaging features may be suggestive of the diagnosis of a ganglion cyst and prompt consideration of imaging-guided percutaneous cyst aspiration, as occurred in three of our cases. Further followup and experience will be necessary to determine the efficacy of this type of treatment relative to surgical and conservative methods. In
Zlatkin
McDade
gan-
sisted primarily of exploration of the nerve and transection of either the superior or inferior transverse scapulam ligament on the basis of clinical and EMG findings (5,6,23,28). MR imaging may allow eartier recognition of suprascapular nerve entrapment in patients with shoulder pain in whom the diagnosis is unsuspected; importantly,
been specifically mentioned case reports of four patients viousty reported ganglion
References MB, Reicher MA, Kellerhouse LE, W, Vetter L, Resnick D. The painful shoulder: MR imaging of the glenohumeral joint. J Comput Assist Tomogr 1988; 12:995-1001. Burk DL Jr. Karasick D, Kurtz AB, et al. Rotator cuff tears: prospective comparison of MR imaging with arthrography, sonography, and surgery. AJR 1989; 153:87-92. Zlatkin MB, Iannotti JP, Roberts MC, et al.
treatment
Figure 8. Posterior glenoid rim fracture with adjacent hematoma. Axial T2*weighted gradient-echo image (400/15, 30#{176} flip angle) shows a high-signal-intensity mass in the infraspinatus fossa (open arrow) adjacent to a posterior glenoid rim fracture (solid arrow).
thank the of case mateMD, An-
16.
17.
18.
19.
20.
21.
shoulder.
diagnostic
performance
Surg Gynecol
Obstet
1959; 109:92-96. Hadley MN, Sonntag VKH, Pittman HW. Suprascapular nerve entrapment. J Neurosurg 1986; 64:843-848. Aiello I, Serra G, Traina GC, Tugnoli V. Entrapment of the suprascapular nerve at the spinoglenoid notch. Ann Neurol 1982; 12:314-316. Clein U. Suprascapular entrapment neuropathy. J Neurosurg 1975; 43:337-342. Donovan WH, Kraft GH. Rotator cuff tear versus suprascapular nerve injury: a problem in differential diagnosis. Arch Phys Med Rehabil 1974; 55:424-428. Edeland HG, Zachrisson BE. Fracture of the scapular notch associated with lesions of the suprascapular nerve. Acta Orthop Scand 1975; 46:758-763. Ganzhorn RW, Hocker JT, Horowitz M, Switzer H. Suprascapular nerve entrapment. J Bone Joint Surg [Am] 1981; 63:492494. Garcia G, McQueen D. Bilateral suprascapular nerve entrapment syndrome. Bone Joint Surg [Am] 1981; 63:491-492. Hirayama T, Takemitsu Y. Compression of the suprascapular nerve by a ganglion at the suprascapular notch. Clin Orthop 1981; 155:95-96. Rask MR. Suprascapular nerve entrapment: a report of two cases treated with suprascapular notch resection. Clin Orthop 1977; 123:73-75. Samno JB. Suprascapular nerve entrapment. Surg Neurol 1983; 20:493-497. Thompson RC Jr. Schneider W, Kennedy T. Entrapment neuropathy of the inferior branch of the suprascapular nerve by ganglia. Clin Orthop 1982; 166:185-187. Yoon TN, Grabois M, Guillen M. Suprascapular nerve injury following trauma to the shoulder. J Trauma 1981; 21:652-655. Zoltan JD. Injury to the suprascapular nerve associated with anterior dislocation of the shoulder. J Trauma 1979; 19:203-206. Kaspi A, Yanai J, Pick CG, Mann G. Entrapment of the distal suprascapular nerve. Int Orthop 1988; 12:273-275. Steiman I. Painless infraspinatus atrophy due to suprascapular nerve entrapment. Arch Phys Med Rehabil 1988; 69:641-643. Drez D Jr. Suprascapular neuropathy in differential diagnosis of rotator cuff injuries. Am J Sports Med 1976; 4:43-45. Ferretti A, Cerullo G, Russo G. Suprascapular neuropathy in volleyball players. Bone Joint Surg [Am] 1987; 69:260-263.
.
i11_
22.
23.
24.
Black KY, Lombardo
JA. Suprascapular nerve injuries with isolated paralysis of the infraspinatus. AmJ Sports Med 1990; 18: 225-228. Post M, Mayer J. Suprascapular nerve entrapment: diagnosis and treatment. Clin Orthop 1987; 223:126-136.
Mestdagh atomical
drome. 25.
Mizuno
mada
H, Drizenko
basis of suprascapular Anat Clin 1981; 3:67-71. K, Muratsu H, Kurosaka
M, Harada
pression
nerve
26.
A, Ghestem
Y, Hirohata
neuropathy
as a cause
of the
P.
nerve
27.
29.
D, Lucas
30.
suprascapular
S, Hassanein
Ma
5:447-451.
Railinlnov
#{149}
M, Weiss
S, Fishel
B, Dekel
S.
34.
scapular
35.
Clin
Orthop
1988;
234:
AgreJC, Ash N, Cameron MC, House J. Suprascapular neuropathy after intensive progressive resistive exercise. Arch Phys
K,
Neviaser
1987; 68:236-238. T:j, Am BR, Neviaser
RJ.
36.
Supra-
31.
32.
nerve denervation secondary to attenuation by ganglionic cyst. J Bone Joint Surg [Am] 1986; 68:627-628. Kaplan PE, Kernahan WTJr. Rotator cuff rupture: management with suprascapular neuropathy. Arch Phys Med Rehabil 1984; 65:273-275. Sarno JB. Suprascapular nerve entrapment. Surg Neurol 1983; 20:493-497.
LF, Roaas
A.
nerve Ada
Compression
of the
after fracture of the Orthop Scand 1978;
49:338-340.
Bilat-
eral suprascapular nerve entrapment syndrome due to an anomalous transverse ligament.
Solheim
suprascapular scapular notch.
scapular
Mohn M, Matzke H. Suprascapular entrapment neuropathy: a clinical, anatornical, and comparative study. Neurosurgery 1979;
Mon
33.
Med Rehabil
Corn-
of pain in palsy of the acJ Bone Joint Surg [Am] 1990;
cessory nerve. 72:938-939. Regachary 5, Burr
0, Sigaard I, Komnum compression Surg Neurol 1984; 22:308-312. nerve
31-33.
M, Ya-
K.
T, Fedders
Suprascapular
syndrome. 28.
Ansyn-
Laulund M.
37.
Weaver
HL.
Isolated
lesions.
Injury
1983; 15:117-126.
suprascapular
nerve
Gelberman RH, Verdeck WN, Brodhead WT. Suprascapular nerve-entrapment syndrome. J BoneJoint Surg [Ami 1975; 57:119-123. Ogino T, Minami A, Kato H, Hara R, Suzuki K. Entrapment neuropathy of the suprascapular nerve by a ganglion. J Bone Joint Surg [Am) 1991; 73:141-147. Semelka RC, Chew W, Hricak H, Tomei E, Higgins CB. Fat-saturation MR imaging of the upper abdomen. AJR 1990; 155:11111116.
February
1992
C.
MD
FritZ,
Clyde
#{149}
Suprascapular Evaluation Entrapment
of the
nerve is frequently differential diagnosis
A. Helms,
with
suprascapular overlooked
in the
of shoulder
pain. The diagnosis is typically not considered until patients develop severe weakness secondary to atrophy of the spinatus (spinous) musculature that the nerve supplies. Twenty-seven masses were identified adjacent to the suprascapular nerve on magnetic resonance (MR) images of the shoulder; there were 21 ganglion cysts, two synovial sarcomas, one Ewing sarcoma, one chondrosarcoma, one metastatic renal cell carcinoma, and one hematoma associated with a fracture. Atrophy of both the supraspinatus and infraspinatus muscles was seen in association with anteriorly located masses and proximal entrapment of the nerve in 11 cases
(40%);
isolated
atrophy
infraspinatus muscle was sociation with posteriorly masses nerve
of the
seen in aslocated
and distal entrapment of the in nine cases (33%). MR imag-
ing may facilitate the diagnosis of suprascapular nerve entrapment in patients with shoulder pain of unclear origin when perineural masses and atrophy of the spinatus musculahire are present. Index terms: Ganglion, 41.361 #{149}Nerves, MR. 41.1214 #{149} Sarcoma, 41.374 #{149} Shoulder, abnormalities, 41.31, 41.32, 41.374 #{149}Shoulder, MR. 41.1214
Radiology
1992;
182:437-444
MD
From
the
Department of Radiology, UniverSan Francisco. Received Norevision requested January 15, 1991; revision received August 13; accepted August 28. Address reprint requests to R.C.F., Marin Radiology Medical Group, 487 Green Glen Way, Mill Valley, CA 94941. C RSNA, 1992
S. Steinbach,
MD
Harry
K Genant,
#{149}
MD
Nerve Entrapment: MR Imaging’
S
on MR images of the shoulder. These cases were retrospectively collected over a penod of 12 months. Nine of the patients were studied at our institution, two were discovered by us during overreading of
pain is a common probtern among patients seeking medical attention. Correct diagnosis and therapy may be difficult due to the broad list of disorders that may HOULDER
cause
this
symptom;
indeed,
diffemen-
tial considerations include rotator cuff and labmat tears, calcific tendinitis, bicipital tenosynovitis, gtenohumemat and acmomioctavicular joint arthritis and instability, subacromiat bursitis, adhesive capsulitis, and cervical radiculopathy. Magnetic resonance (MR) imaging of the shoulder is often performed in this group of patients when the diagnosis is uncertain (1-3). Although it is welt described in the literature (4-36), suprascapulam nerve entrapment has been regarded as a relatively uncommon condition that is easily overlooked in the differential diagnosis of shoulder discomfort. The suprascaputam nerve is a mixed motor and sensory nerve that carries pain fibers from the glenohumemat and acmomioctavicutar joints and provides motor supply to the supraspinatus and infraspinatus muscles (Fig i). Patients
with
trapment
suprascaputam
typically
specific
nerve
present
shoulder
pain.
with
25 asymptomatic
healthy
studied
for
to assess
masses
adjacent
nerve;
these
cruited
labrum
(mean,
was
symptomatic
shoulder
40 years).
The
study
group who to the
consisted
The
right
shoulder
symptomatic
the
in eight
left
cases.
The asymptomatic group consisted of 20 men and five women aged 22-56 years (mean, 36 years). The right shoulder was imaged
in 12 volunteers,
and
the left
shoulder was imaged in 13. MR imaging was performed system
(Signa;
waukee) face
with
GE Medical
with
a dedicated
coil anteriorly
ing two
patients MR
Mil-
shoulder
sur-
in alt of the volunteers were
system
America Catif)
by
a i.5-T
Systems,
and in 24 of the 26 patients.
cisco,
The remain-
imaged
(MT/S;
MRI, using
with
a
Diasonics
South
San
a 5-inch
Fran-
anterior
face coil. Oblique coronal, oblique axial images were obtained
sum-
sagittal,
and
in all cases. A variety of pulse sequences was used. At least one Ti-weighted spin-echo pulse se-
quence
(600-800/20-30
msec/echo case.
time
Either
[repetition
msec])
was
a T2-weighted
used
(1,800-2,000/20-60)
weighted
gradient-echo
angle)
sequence was
each case. At least one quence was performed
gradient-echo
tients
were
masses
pulse
or a T2*
pulse
30#{176} flip
in whom
time in each
spin-echo
sequence
(300-400/15-30,
may
used
in
se-
in 13 of the 27 paidentified.
Image thickness was 4-5 mm with or without a 1-mm intersection gap. Two images were usually obtained for the spin-echo and
four
images
were
of 26 sympto have nerve
cuff of 22 10-75
and
METHODS
were noted suprascapular
to eval-
subjects.
in 18 cases,
was
sequences,
tomatic patients mass adjacent
re-
of the rotator
in asymptomatic
years
Toshiba
tar nerve.
AND
been study
The symptomatic group consisted male and four female patients aged
non-
sity of California, vember 26, 1990;
PATIENTS
had
and
of
suprascapular
of a separate
the MR appearance
was
presence
to the
uate
15 cases and inclua group of
volunteers
the
volunteers
as part
0.35-T
Suprascaputam
noted at MR imaging that entrapment of the supmascapu-
outside cases, and the remaining were sent to us for consultation sion in this study. In addition,
en-
nerve entrapment is usually not considemed until profound weakness and denervation atrophy of the spinatus (spinous) musculature is apparent, resulting in prolonged disability. MR imaging, commonly performed in patients with shoulder pain of uncertain origin, may allow earlier recognition of suprascapulan nerve entrapment. In this article, we describe the appearance of clinically unsuspected gangtion cysts and other soft-tissue masses cause
I
Lynne
#{149}
a
Abbreviations: NCV = nerve
EMG
conduction
=
electromyography,
velocity.
obtained
for the gradient-echo 256
or 256
sequences.
x 192
16 cm2 field
matrix
of view.
dimeglumine
was
A 256 used
a
Gadopentetate
(Magnevist;
Berlex
Labora-
tories, Wayne, NJ) was intravenously ministered at a dose of 0.1 mmol/kg
Ti-weighted tients and
one
weighted
fat-saturation
was
were
in three
administered
dimeglumine of enhancement.
sequence six
patients
gadopentetate
sequence
have
de-
in the symptomatic follow-up MR stud-
of these patients had undergone 5 years earlier, but only
MR imaging report was asymptomatic cyst
was
of
been
(37).
Five of the patients group also underwent one
pulse of the
to improve the conspicuity The technical features
this fat-saturation scribed previously
ies;
adbefore
imaging in five of the paof the volunteers. A Ti-
performed
who
x
with
available for review. subject in whom
found
underwent
the
The one a ganglion
follow-up
im-
aging tetate
with administration of gadopendimeglumine 10 months after the
initial
study.
Each
case
was
assessed
skeletal radiologists following findings ence and location
by two
muscuto-
(R.C.F., C.A.H.) for the on MR images: presof a mass, size of the
mass, signal intensity T2-, or T2*weighted
of the images,
mass and
on Ti-, en-
hancement characteristics. The presence abnormal signal intensity or decreased bulk of either the supraspinatus or in-
of Figure
fraspinatus muscles was noted and the degree of muscular atrophy graded as mild, moderate, or severe. Fatty infiltra-
tion was characterized streaks
and defined
of increased
the affected
signal
muscle
by
intensity
within
on the Ti-weighted
images that decreased with T2 weighting. Increased water or “edema” within a muscle was characterized by signal intensity that was isointense with unaffected musdes
on
the
creased
Ti-weighted
images
on the T2-weighted
areas
of signal
teromedial noted
void
when
Clinical
of the
to the
glenoid
suits
were
was obtained
of the patients. Electromyography and nerve conduction velocity were
available
in nine
in all
(EMG) (NCV) repatients.
The
and
at EMG
of combined
infraspinatus
muscle
rophy,
whereas
fined
as isolated
tus
muscle
distal
atrophy
supmaspinatus
denervation
entrapment
tow-up ranged age, 7 months).
went
surgery.
symptoms
were
to impingement
than
due
identified gg
The
of a malignant
thought
tients underwent the preoperative
to be
resulting
nerve
two patients acromioplasty,
underwent and the
underwent
computed
on MR images
(presumed
armasses
gan-
exploration of a ganglion
for
nerve
en-
tomographic
(CT)-
guided
percutaneous
aspiration
pected caputar
ganglion cysts resulting in suprasnerve entrapment. One patient adjacent
entrap-
to
trapment on the basis of MR imaging and EMG findings. Three additional patients
treated
rather
paor bi-
of the pa-
in suprascaputar
nerve
secondary cuff
with
adjacent
Seven
surgical diagnosis
hematoma
of fol-
rotator
neoptasm
nerve.
de-
was
of the infraspina-
duration
shoulder
the
supraspinatus
of the suprascapular
not treated. Four surgical resection
the suprascapular
a posterior was
duration
noted,
and
as unchanged, asymptomatic.
from 2 to 25 months (averThirteen patients underIn two of these patients, the
to suprascapular
#{149} R2ilinInai
opsy
The
of the
ment; these throscopic
cysts) were underwent
with
alone.
to follow-up.
glion tients
at-
Twenty-five of the 26 patients were available for follow-up; one patient was lost
of the
nerve.
and
The
nerve
infraspinatus
passes
muscles
beneath
the supe-
nor transverse scapular ligament in the suprascapular notch, then runs deep to the supraspinatus muscle and the inferior transverse scapular ligament to pass through the spinoglenoid notch. The inset shows a ganglion cyst in the suprascapular notch causing entrapment of the nerve anteriorly and a ganglion cyst in the spinoglenoid notch causing entrapment of the nerve posteriorly. Anterior entrapment of the nerve will result in atrophy of both the supraspinatus and infraspinatus muscles, whereas posterior entrapment will result in selective atrophy of the infraspinatus muscle. Entrapment of the suprascapular nerve anywhere along its course is associated with deep, poorly localized shoulder pain. hg. = ligament.
cyst
location of the mass and the presence of atrophy on MR images were correlated with the EMG findings of either proximal or distal suprascaputar nerve entrapment. Proximal entrapment was defined as evidence
view
the course
Focal pos-
present.
correlation
Posterior
to reveal
in-
images.
adjacent
aspect
and
1.
sectioned
glenoid
rim
fracture
and
to the suprascapular with
follow-up
conditions
were
improved,
was classified
or completely
mass
ranging
in size
from
1 to 7 cm with a mean maximum diameter of 2.4 cm was noted in alt 26 patients and in one of the 25 votunteems.
A component
of the
creased
mass
27 cases;
signal
weighted
posterior
intensity
images
intensity images.
was
extension
nat intensity 5 mm
this
on
and
on the T2A focal area noted
finding
Ti-
signal
or T2*weighted of decreased
sig-
in size from
adjacent
was
noted
on the
ages
five
2 to
to the
pos-
of the glenoid notch in nine
prominent in the
the
seen de-
increased
ranging
was
sequences Atrophy was seen
RESULTS A definite
i2 of the
into the infraspinatus fossa was in six. All of the masses exhibited
tenomedial aspect the spinoglenoid
immobilization.
of clinical their
of sus-
present in the spinogtenoid notch of the scapula in 26 of these 27 cases. Extension of the mass anteriorly into the supraspinatus fossa was seen in
in cases;
to be more
gradient-echo
cases
im-
in which
these
were performed (Fig 2). of the supmaspinatus muscle in ii of the 27 cases (40%)
and was mild in five, moderate in two, and severe in four. Atrophy of the infraspinatus muscle was seen in 20 of the
in five,
27 cases
moderate
(74%)
and
was
in ii,
and
severe
I3Phri12ri
mild
in 1QQ.
I
Figure
2.
Ganglion
cyst
in the
spinoglenoid
notch resulting in suprascapular nerve entrapment. (a) Ti-weighted oblique coronal MR image (800/20) demonstrates a rounded 1.5-cm
a.
mass
with
low
signal
intensity
(arrow)
inferior to the posterior aspect of the supraspinatus muscle. (b) T2*weighted oblique coronal MR image (400/20, 30#{176} flip angle) shows increased signal intensity of the ganglion cyst (black arrow). Note focal area of decreased signal intensity along the inferolateral aspect of the cyst (white arrow). (c) Ti-weighted axial MR image (800/20) demonstrates a rounded mass with low signal intensity (arrow) just lateral to the distal suprascapular nerve. (d) Gradient-echo axial MR image (300/10, 90#{176} flip angle) shows the ganglion cyst (curved arrow) and focal area of low signal intensity within the cyst (straight arrow), likely representing cortical bone or hemosidenn. Roughening and irreg-
b.
ularity
of the
adjacent
surgery; however, were found within
intensity on
within
the
glenoid
no flecks the cyst.
the
was
found
of cortical
atrophic
T2-weighted
at
bone
muscles
images
was
noted
in five patients. Interestingly, in one of these patients the abnormal signal intensity within the infraspinatus muscle completely resolved and the spinoglenoid notch ganglion cyst spontaneously decreased in size from 3.0 to 0.8 cm;
d.
C.
four (Fig 3). Isolated atrophy of the infraspinatus muscle with sparing of the supraspinatus muscle was seen in nine of the 27 cases (33%). Isolated atrophy of the supraspinatus muscle with sparing of the infraspinatus muscle
was
not
seen
Increased signal ment, on swelling scapular
nerve
Ganglion
in our
intensity, of the was
not
patients.
enhancesupraidentified.
Cysts
Twenty-one onstrated MR
of the 27 masses findings
dem-
characteristic
marginated
with
homoge-
neous Ti and T2 prolongation. They were variably rounded, septated, or tubular. Alt 2i ganglion cysts were in men; ages ranged from 25 to 68 years (mean, 39 years). The cysts were tocated on the right side in 14 men and on the left side in seven. The one mass detected in the asymptomatic
seen,
subject
changed showed
at iO-month no evidence
Volume
182
#{149} Number
remained
un-
follow-up and of enhancement 2
and
this
dimegtumine atrophy has been
patient
has
remained
asymptomatic at 20-months followup. Interestingly, the four symptomatic patients with ganglion cysts and evidence of suprascapulam nerve entrapment who received gadopentetate dimeglumine had rim enhancement around the margins of the cyst (Fig 6). Etectmodiagnostic studies (EMG and NCV)
of a gangtion cyst (Figs 2-6). The ganglion cysts were all well defined and smoothly
with gadopentetate (Fig 4). No muscular
were
21 patients
performed with
in nine
ganglion
cysts
of the and
the results were positive for suprascapulam nerve entrapment in each of these cases. Atrophy was seen on MR images in three of the four cases in which the EMG indicated that the supraspinatus Atrophy was seven
of the
muscle seen on nine
cases
was abnormal. MR images in in which
the
EMG indicated that the infraspinatus muscle was abnormal. The overall correlation between MR imaging and EMG abnormalities was, therefore, 77% (iO of the 13 muscles with EMG evidence of denervation were abnormat on MR images). Increased signal
this
decrease
in size
and
resolution of infraspinatus edema was accompanied by resolution of pain and weakness in the 8-month interval between MR examinations. Proximal entrapment was suggested on the basis of both supraspinatus and infraspinatus muscle abnommalities at EMG in four of nine cases.
A ganglion
cyst
was
noted
ex-
tending anteriorly into the supraspinatus fossa in three of these four cases (75%) with EMG evidence of proximal entrapment (Figs 5, 6). Anterior extension of a ganglion cyst was seen in only one of five cases (20%) with EMG evidence of distal entrapment; of note, in this case, EMG was performed in the 3-month interval between MR examinations that demonstmated spontaneous rupture of this anteriorly extending cyst, perhaps accounting for the lack of an abnommat supraspinatus muscle on the EMG. A component of the ganglion cyst
was
seen
in the
spinoglenoid
notch in each of the nine cases in which the EMG indicated distal entrapment. Definite proof of the diagnosis was available in eight of the ganglion cysts,
six of which
had
EMG
evidence
of suprascaputam nerve entrapment. Five of these cysts were mesected at surgery, and the diagnosis was histologically
proved.
In addition,
Radiotov
three
#{149}
Figure
3. Ganglion cyst in the spinoglenoid notch resulting in isolated denervation of the infraspinatus muscle. (a) T2-weighted axial MR image (2,000/60) reveals a 1.0-cm mass with high signal intensity (arrow) adjacent to the distal
suprascapular
nerve.
Atrophy
and
increased signal intensity of the infraspinatus muscle (i) is also noted. (b-d) Sequential medial to lateral Ti-weighted oblique sagittal MR images (800/20) demonstrate the course of the suprascapular nerve (white arrows) beneath the supraspinatus muscle in the supraspinatus fossa (b), through the spinoglenoid notch (c), and beneath the infraspinatus muscle in the infraspinatus fossa (d). The ganglion cyst is seen laterally in the spinoglenoid notch (black arrow in d). A = acromion, C = coracoid process, S = supraspinatus muscle, i = infraspinatus muscle.
cysts ance,
were which
cyst
fluid.
a.
b.
aspirated with CT guidyielded typical viscous Each of these eight patients
presented with pain and weakness and was asymptomatic after treatment; the duration of follow-up ranged from 6 months). A presumptive
2 to i3 months
(average,
diagnosis
was
made
on the basis of imaging features EMG findings in the remaining ganglion
cysts.
In two
cases,
and i3
appearing ganglion cysts, each with EMG evidence of denervation atnophy, were explored and not identified at surgery. In one of these cases, the patient improved and the ganglion cyst was not apparent on follow-up
MR
images;
the
gangtion
cyst
likely
spontaneously ruptured pmeopematively on was lanced during surgical exposure. In the other case not identi-
fled
at surgery,
the
symptomatic
due
MR image
in the cyst; the not seen
to the
posterior means
patient
remained
postoperatively
follow-up change glion likely
and
showed
appearance gangtion at surgery
inability
the gan-
notch approach
conservatively. fraspinatus
they
were
Atrophy muscle was
with
the
MR
of the present
appearance
further patients.
MR
Other
Masses
or pursued
not
imaging
results.
Two
these scopic
patients underwent acrornioptasty and
arthrorepair
Soft-tissue
in these
of
on
of these
of the
spina-
MR images. EMG in these patients.
other
identified nerve
(four iO-68
females years). plasms were readily from the gangtion by noting adjacent
The
suprascapular
motor
and
nerve
sensory
is a mixed
nerve
that
is de-
(Ewing
than
and
gan-
adjacent in six pa-
to
and two males Malignant neodistinguished cysts on MR images bone destruction
sarcoma,
chon-
omohyoid
muscles
to enter
glenoid
notch,
passing
beneath
inferior at the spine.
transverse scapular lateral border of the In the supraspinatus gives off two motor branches supraspinatus muscle and sensory branches from the
the
ligament scapular fossa, it to the receives capsular
and
In the infraspinatus
fossa,
catty
in each of the five malignant masses. A definite fracture of the posterior glenoid rim was seen adjacent to a hematoma that extended
two
to the
tmaprnent
joint and scapula (5,ii). of the nerve anteriorly,
into
proximal
to the motor
proved
spinoglenoid
notch
in a 68-
the
supraspinatus fossa through the suprascapulam notch, passing beneath the superior transverse scapular tigament. The nerve then runs deep to the supraspinatus muscle to enter the infraspinatus fossa through the spino-
tient in this series who was administened gadopentetate dimegtumine (Fig 7). The diagnosis was pathologi-
the
was
DISCUSSION
three
drosarcoma, and metastatic renal cell carcinoma) and heterogeneous signal intensity and lobular contours in two cases (synoviosamcoma). Uniform enhancement was noted in the one pa-
of
8). Each
atrophy
nived from the upper trunk of the brachial plexus originating from the fourth, fifth, and sixth cervical nerve roots. It passes deep to the trapezius masses
cases
(Fig
had
muscles performed
tus
with
inin
of a
with
#{149} Radiology
studies
in
in one.
woman
entrapment
treated
EMG
cases,
440
EMG
three
year-old
six patients
other’s is unthe diagnosis
nerve
tients aged
ganglion cyst; treatment was directed to the rotator cuff in each of these variable
with
the
patients
to the ganglion cyst seen images had not been verified
that
In three cases, theme was evidence of rotator cuff disease in addition to a mass
secondary on MR
teams;
of these
of suprascaputar
glion cysts were the suprascapular
seen on cases in im-
being
both cases, and confirmatory evidence of distal suprascapulam nerve entrapment was present
tendon
of one
has improved and the changed. At follow-up,
case
by
performed. Spontaneous rupture was follow-up MR images in two which the patients’ conditions
while
supmaspinatus
condition
the
was
proved
small
no
of the cyst was in this
to visualize
spinoglenoid of the anterior
d.
C.
typical
ligarnentous shoulder and
tus
motor muscle
shoulder
structures acromioctavicutar
branches as
welt
as
of the joints.
off
it gives
infraspina-
filaments
branches February
to
the
En-
be1992
a.
b.
C.
Figure rounded
4.
30#{176} flip weighted evidence
angle) shows increased signal intensity of the ganglion cyst (arrow). axial MR image (800/20) obtained with fat suppression after intravenous of enhancement (arrow). This mass was identical in appearance to that
Ganglion
1.5-cm
cyst
mass
in the
(curved
spinoglenoid
arrow)
notch
just lateral
of an asymptomatic
to the distal
volunteer.
suprascapular
(a) Ti-weighted
nerve (straight H = humeral
axial
arrows). head, G
administration seen on an MR
=
MR
image
(b) T2*weighted glenoid, Sp
(800/20)
scapular spine. dimeglumine 10 months earlier.
a
the nerve is also ondary to a sling of fixation
thought
(400/20,
(c) Tishows
=
of gadopentetate image obtained
sites
demonstrates
axial MR image
no
to occur
sec-
effect at potential in the supmascaputam
notch and spinogtenoid notch (25,26). Compression of the suprascapulam nerve by a ganglion cyst has been described in 24 surgically proved cases;
with
24 of the
pain,
fraspinatus
presented
atrophy
muscle,
combined praspinatus des
24 patients
22 had
of the
and
four
atrophy of both and infraspinatus
(5,10,12,15,30,36).
a.
b.
Figure 5. Ganglion cyst in a patient with infraspinatus muscle atrophy. (a) Ti-weighted lar mass with low signal intensity extending
clinical
the supraspinatus
notch
(2,000/60)
Mark
fossa
shows
Forte,
Colorado
and
increased
MD, and Springs,
spinoglenoid signal
Luke
and EMG evidence of supraspinatus axial MR image (800/20) demonstrates along the length of the suprascapular
intensity
Cesaretti,
of the
MD, Department
muscle, wilt the supraspi-
natus
and
muscles.
infraspinatus
Dis-
tat entrapment of the nerve, within the spinogtenoid notch on the infraspinatus fossa, will result in selecof the
infraspinatus
mus-
cle. Entrapment of the suprascapular nerve anywhere along its course is usually associated with deep, poorly localized shoulder pain. Occasionally, as in one of our cases, there may be dramatic atrophy and weakness without pain in cases of documented entrapment (19,21). The clinical features and treatment of suprascaputan nerve entrapment have been welt described (4-36). To our knowledge, there have been 139 reported cases since the first description of this syndrome in 1959. The diagnosis is usually not considered Volume
182
cyst
axial MR image
(arrows).
of Radiology,
(Case
USAF
courtesy
Academy
of
Hospital,
#{149} Number
cyst mass
was discovered involved the
2
sumuscases,
positive, ganglion
at surgery. supmascutan
The notch
in four of the 24 cases, the supmaspinatus fossa in one, the spinogtenoid notch fossa
the
in i8, in one.
and the Ganglion
spinoglenoid
cases, extended supraspinatus
the supraspinatus in atrophy of both
atrophy
(b) T2-weighted
ganglion
Cob.)
neath result
tive
(arrows).
and a tubunerve in
the
In most
the findings at EMG were and a clinically unsuspected
in-
had
infmaspinatus cysts involved
notch
in alt of our
until the development of dramatic atrophy of the spinatus musculature after an average of i2 months of shoulder pain. Often it is the patient who first notices a concavity over the posterior scapula as a manifestation of severe infraspinatus muscle atro-
tended posteriorly into the infraspinatus fossa in four. To our knowledge, theme are no reports of suprascaputan nerve entrapment in the radiology literature, reflecting the previously limited mole of diagnostic imaging in the evatuation of these patients. Plain radio-
phy;
clinical
graphs
tory
of weakness,
examination
with
ings at EMG and studies diagnostic
is confirma-
positive
find-
nerve conduction of nerve entrap-
of causes
of injury
or en-
tnapment of the suprascaputar nerve have been described, including scapulam (9,33) and humemat (27) fractures, anterior shoulder dislocation (i7), penetrating or surgical trauma (34), compression by tumors (35), and anomalous or thickened superior (ii) or inferior (6,21,28) transverse scaputan ligaments.
Traction
on kinking
of
be useful
that
cysts have the posterior
ment. A variety
may
fractures prascaputar
21
anteriorly into the fossa in eight, and ex-
may nerve.
in detecting
damage Although
the
suganglion
been noted to arise from joint capsule in several
of our cases and in at least five of the reported cases, shoulder amthmogmaphy
has
not
demonstrated
filling
of
these cysts (ii,i4). CT also failed to depict a large recurrent gangtion cyst in one report in which it was performed (4). The preoperative detection of a mass causing suprascaputam nerve entrapment has been recently reported in three cases, however, by Radiology
#{149} 441
a.
b.
Figure
6.
MR image creased
Ganglion
cyst
(2,000/60)
shows
signal
septated
intensity
mass
with
suppression after S = supraspinatus
using sound
that
with
a tubular
are
high
seen
intensity
with the
anterior
administration
of CT and
cause
evidence
mass
throughout
signal
intravenous muscle.
a combination (36).
Masses
in a patient
C.
of severe
high
signal
infraspinatus
intensity
infraspinatus
muscle
to the supraspinatus
of gadopentetate
and
moderate
supraspinatus
muscle
atrophy.
(a) T2-weighted
extending along the floor of the supraspinatus fossa. Atrophy (i). (b) More superior T2-weighted axial MR image (2,000/60) muscle (s). (c) Ti-weighted axial MR image (600/20) obtained
dimeglumine
shows
enhancement
of the
rim
of this
ganglion
cyst
axial
and
in-
shows
a
with
fat
(arrows).
ultra-
supmascapular
nerve entrapment may now be welt localized and characterized with MR imaging, reflecting the superior softtissue
contrast
dition, atrophy viding
of this
modality.
In ad-
MR imaging may demonstrate of the spinatus muscles, proevidence of denervation sec-
ondary
to the
visualized
mass.
Gan-
glion cysts account for the majority of these masses and are typically homogeneous, have low signal intensity on Ti-weighted images and high signal intensity on T2-weighted images, and show rim enhancement with gadopentetate dimeglumine. While the diagnosis of suprascapulam nerve entrapment has traditionally been made with EMG and NCV studies,
MR
imaging
may
provide
(5,23).
MR
imaging
is corn-
monly performed in patients with shoulder pain of uncertain origin, whereas the specific diagnosis of neumat entrapment must be considered to perform an EMG study. Indeed, each of the 2i ganglion cysts noted in this series was not suspected and was not palpable.
clinically
A probable ganglion cyst was noted in the spinoglenoid notch of one of the 25 volunteers. Since a neural tumom such as a schwannoma could have a similar appearance, we brought this patient back to undergo follow-up imaging with administration of gadopenetate dimeglumine. The mass did not enhance, and this 442
Radiotogy
#{149}
b.
Figure 7. Synoviosarcoma adjacent to the suprascapular nerve. (a) Ti-weighted oblique coronal MR image (800/20) demonstrates a lobulated mass (arrows) and severe atrophy of the supraspinatus muscle. (b) Ti-weighted oblique coronal MR image (800/20) obtained after intravenous administration of gadopentetate dimeglumine shows uniform enhancement of the mass (arrows). Areas of low signal intensity within the mass corresponded to radiographically evident calcifications.
compte-
mentary anatomic information and allow earlier diagnosis of suprascaputar nerve entrapment. The hallmark of this diagnosis is pain followed by weakness and atrophy of the spinatus muscles
a.
subject
did
not
symptoms
develop
signs
of entrapment.
or
It seems
likely that a gangtion cyst, while capable of causing entrapment and not uncommon in this location, may not always be the cause of a patient’s shoulder pain. In this sense, many of these ganglion cysts may be anatogous
and
to disk
the
atic unless structures
protrusions
patients
may
in the
spine,
be asymptom-
mass effect develops.
on
the
neural
Spontaneous decompression of a ganglion cyst was noted in at least two patients in this series. Additionally, spontaneous rupture may have occurred in one of our cases in which the mass could not be found at sumgery
and
was
not
present
on
a post-
operative MR image. Given the nurnben of ganglion cysts we identified within i year with MR imaging and
the observation dramatically only speculate masses may
that decrease
these cysts may in size, one can
on how often have accounted
pmascaputam
nerve
was
conservatively.
treated
these for su-
entrapment
that Indeed,
a
recent report emphasized effective conservative therapy in four patients with EMG evidence of distal suprascapular nerve entrapment of unclear origin (22); perhaps some of these patients had ganglion cysts in the spinogtenoid notch that ruptured as in our patients. All 21 of our patients with gangtion cysts catty
were proved
male, as were all 24 surgicases described in the
literature (5,iO,12,i5,30,36). An association with weight lifting may partially account for this finding, as seven of our 2i cases occurred with weight lifters. Moreover, weight lifting has February
1992
lence tients
of rotator cuff with shoulder
cysts
should
source
not
be discounted
of symptoms
especially
Acknowledgments: The authors following people for contribution rial: John Barr, MD, Luke Cesaretti,
disease in papain. Ganglion
if atrophy
as the
in these
patients,
is present
on
drew Deutsch, MD, Mark Forte, MD, Malcolm Friedman, MD, Marc Goldberg, MD, Ned Grove, MD, Phoebe Kaplan, MD, Howard Lee, MD, Chaney Li, MD, Russell Low, MD, Richard Mitchell, MD, and Christian Neumann, MD.
MR
images. Minor degrees of increased signal intensity are commonly seen in the supraspinatus tendon and may not necessarily be the source of symptoms. EMG should be performed and
Extension glenoid
of the hematoma notch
was
noted
into
the spino-
on other
images.
glion cyst if evidence of suprascapular nerve entrapment is present. Surgical and conservative therapy have each been advocated in patients with supmascaputar nerve entrapment
2.
(5,19,22,23).
3.
4.
of MR imaging. Radiology 1989; 172:223229. Kopell HP, Thompson WAL. Pain and
directed
(iO,i2,30,36)
as well
in the with pmecysts
as in the
case
me-
ports of patients with EMG evidence of supmascapulam nerve entrapment treated conservatively (22,29). Also, an anatomic study has shown that distal suprascapulam nerve entrapment may predominate in men because of the differences in the spinoglenoid ligament. The spinogtenoid ligament was absent or rudimentary in 60% of women compared with 13% of men; also, the size of the spinoglenoid canal formed by the ligament was
more
variable
in men
(18).
Focal areas of tow signal intensity were noted in the spinoglenoid notch adjacent to nine of the ganglion cysts in our series. We believe this nepresents
a small
cause
of the
tensity
and
area
of cortical
dephasing
bone
of signal
“blooming”
that
be-
in-
was
present on gradient-echo images. Attemnatively, this tow signal intensity may
be due
to hemosiderin
or catcifi-
of an abnormal spinoglenoid ligament. A clean explanation for this finding was not found at surgery in each case; however, roughening of the posterior glenoid was noted in one of our cases (Fig 2), suggesting a traumatic origin. Ganglion cysts were seen in association with abnormalities of the rotator cuff in three patients. This has also been described previously (8,20,31) and is not surprising given the prevacation
Vnliimo
ig,
#{149} MIlniliDr
“
toward
Surgical
the
therapy
1.
has
earlier
diagnosis
and
con-
summary,
entrapment relatively easily
suprascaputar
has been uncommon
overlooked
regarded condition
of shoulder
diagnosis
is usually
as a that
discomfort. not
weights.
experience, was
advent
On
the
we believe
likely
underdiagnosed
of MR
imaging.
6.
8.
9.
10.
ii.
12.
13.
is
The
14. 15.
considered
until profound weakness and denervation atrophy of the spinatus musculatrine are apparent, resulting in prolonged disability. MR imaging may allow early recognition of suprascapulan nerve entrapment secondary to clinically unsuspected masses. Ganglion cysts account for the majority of the masses causing entrapment and seem to occur exclusively in men, often in association with a history of lifting
5.
7.
differential
basis
of our
this
syndrome before
#{149}
the
cuff tears:
the frozen
nerve
in the
diagnosis
Rotator
proper
therapy allows for prompt alleviation of the pain associated with entrapment and better prognosis for the meturn of motor function (5,23). In addition, MR imaging can help identify and localize a mass preopematively, obviating the need for an exploratory surgical procedure in such cases. Furthermore, characteristic MR imaging features may be suggestive of the diagnosis of a ganglion cyst and prompt consideration of imaging-guided percutaneous cyst aspiration, as occurred in three of our cases. Further followup and experience will be necessary to determine the efficacy of this type of treatment relative to surgical and conservative methods. In
Zlatkin
McDade
gan-
sisted primarily of exploration of the nerve and transection of either the superior or inferior transverse scapulam ligament on the basis of clinical and EMG findings (5,6,23,28). MR imaging may allow eartier recognition of suprascapular nerve entrapment in patients with shoulder pain in whom the diagnosis is unsuspected; importantly,
been specifically mentioned case reports of four patients viousty reported ganglion
References MB, Reicher MA, Kellerhouse LE, W, Vetter L, Resnick D. The painful shoulder: MR imaging of the glenohumeral joint. J Comput Assist Tomogr 1988; 12:995-1001. Burk DL Jr. Karasick D, Kurtz AB, et al. Rotator cuff tears: prospective comparison of MR imaging with arthrography, sonography, and surgery. AJR 1989; 153:87-92. Zlatkin MB, Iannotti JP, Roberts MC, et al.
treatment
Figure 8. Posterior glenoid rim fracture with adjacent hematoma. Axial T2*weighted gradient-echo image (400/15, 30#{176} flip angle) shows a high-signal-intensity mass in the infraspinatus fossa (open arrow) adjacent to a posterior glenoid rim fracture (solid arrow).
thank the of case mateMD, An-
16.
17.
18.
19.
20.
21.
shoulder.
diagnostic
performance
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February
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