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                                                                                                                                              ORIGINAL RESEARCH
                                                        Parsonage-Turner Syndrome:
                                                        MR Imaging Findings and Clinical
                                                        Information of 27 Patients1




                                                                                                                                             MUSCULOSKELETAL IMAGING
Cree M. Gaskin, MD
                                                             Purpose:    To review retrospectively the magnetic resonance (MR)
Clyde A. Helms, MD
                                                                         imaging findings and clinical information of patients with
                                                                         Parsonage-Turner syndrome (PTS).

                                                         Materials and   The institutional review board did not require its formal
                                                             Methods:    approval or informed patient consent at the time of the study.
                                                                         However, the study was HIPAA compliant. The information
                                                                         in a computerized database of 2875 consecutive shoulder MR
                                                                         examinations was retrospectively reviewed. With use of key
                                                                         terms, the database software identified 81 examinations po-
                                                                         tentially associated with PTS. Both authors together re-
                                                                         viewed the 81 imaging reports and the corresponding pa-
                                                                         tients’ medical records. In consensus, they made the diagno-
                                                                         sis of PTS in 21 patients (two with bilateral involvement) on
                                                                         the basis of MR findings, electromyographic results, and clin-
                                                                         ical data. They also examined the data of an additional six
                                                                         patients (one with bilateral involvement) obtained from out-
                                                                         side facilities. Ultimately, 30 shoulders of 27 patients (18
                                                                         male, nine female; age range, 12– 81 years; mean age, 41
                                                                         years) were evaluated. The MR findings and clinical informa-
                                                                         tion (ie, regarding atrophy, pain, weakness, electromyo-
                                                                         graphic results, neck and spine history, trauma, excessive
                                                                         overhead activity, recent surgery, vaccination, and illness) of
                                                                         all patients with PTS were reviewed. MR findings of diffuse
                                                                         high T2 signal intensity abnormality and fatty atrophy of
                                                                         muscles were evaluated to assess the pattern of nerve in-
                                                                         volvement. Structural causes (eg, ganglion cyst or other
                                                                         mass) of neurogenic high T2 signal intensity abnormality
                                                                         were excluded at MR imaging.

                                                              Results:   Twenty-nine (97%) of 30 shoulders had suprascapular nerve
                                                                         involvement; in 15 (50%) shoulders, the involvement was
                                                                         limited to this nerve. Fifteen (50%) shoulders had axillary
                                                                         nerve involvement; in only one (3%) shoulder, the involve-
                                                                         ment was limited to this nerve. One shoulder (3%) had
                                                                         subscapular nerve involvement. Nine (30%) shoulders dem-
                                                                         onstrated focal muscular atrophy. Eleven (41%) of 27 pa-
                                                                         tients also underwent electromyography; all of these patients
                                                                         demonstrated neuropathies that matched the patterns of
                                                                         neurogenic high T2 signal intensity abnormality seen at MR
1
                                                                         imaging.
  From the Department of Radiology, Duke University
Medical Center, Durham, NC. From the 2002 RSNA An-
nual Meeting. Received March 10, 2005; revision re-        Conclusion:   The suprascapular nerve was almost invariably involved
quested April 20; revision received July 24; accepted                    (in 97% of shoulders) in patients with PTS. Axillary nerve
August 25; final version accepted October 3. Address                      involvement also was commonly observed (in 50% of
correspondence to C.M.G., Department of Radiology,                       shoulders). Subscapular nerve involvement was uncom-
UVA Health Sciences Center, Box 800170, Lee St, Char-
                                                                         mon (in 3% of shoulders).
lottesville, VA 22947 (e-mail: cmg9s@virginia.edu).

    RSNA, 2006                                                            RSNA, 2006


Radiology: Volume 240: Number 2—August 2006                                                                                            501
MUSCULOSKELETAL IMAGING: MR and Clinical Findings of Parsonage-Turner Syndrome                                                     Gaskin and Helms




P
       arsonage-Turner syndrome (PTS),         dle syndrome. Since then, the condition      eral examinations. Both authors to-
       also known as acute brachial neuri-     has generally been referred to by the        gether reviewed the imaging reports of
       tis and neuralgic amyotrophy, is an     acronym PTS. In 1972, Tsairis et al (4)      these 81 examinations and the corre-
uncommon—but not rare—clinical prob-           reported the long-term outcomes of 84        sponding patients’ computerized medical
lem. Although this abnormality typically has   patients with this disorder, although        records. One of the authors (C.A.H.) was
a characteristic manifestation—namely,         they preferred the term brachial plexus      one of the six radiologists who originally
acute onset of severe shoulder pain fol-       neuropathy. In 1998, Helms et al (1)         interpreted the MR images for clinical
lowed shortly thereafter by weakness of        described the MR findings of PTS in           purposes. At the start of the 64-month
at least one shoulder muscle—it is often       three patients, choosing to continue us-     period, this author had 20 years experi-
confused clinically with more well-            ing this name of the disorder until the      ence with musculoskeletal MR imaging.
known disorders such as cervical spon-         actual cause is identified. A few addi-           Fifty-eight patients were excluded
dylosis, rotator cuff tear, shoulder im-       tional case reports describing similar       because of insufficient clinical data; a
pingement syndrome, and acute calcific          characteristic MR findings have fol-          clear temporal relationship between the
tendonitis (1–7). Therefore, failure to        lowed (7,8).                                 neurologic disorder and trauma, which
consider PTS may result in inappropri-             The MR finding most typical of PTS        suggested traumatic neuropathy; or a
ate treatment or even unnecessary sur-         is that of diffuse high signal intensity     morphologic cause of the neurogenic
gery. Although this diagnosis has long         involving one or more muscles inner-         high T2 signal intensity abnormality at
been recognized within the medical,            vated by the brachial plexus depicted on     MR imaging (eg, an entrapment neurop-
neurologic, and orthopedic literature,         T2-weighted images. T1-weighted MR           athy caused by a ganglion or other mass
its characteristic magnetic resonance          images also may show atrophy of the          in the suprascapular notch).
(MR) imaging appearance has been de-           affected muscle(s). The pattern of mus-          The remaining 21 patients (two of
scribed only within the past 10 years          cular involvement should match the dis-      whom underwent bilateral examina-
(1). The delayed description of the MR         tribution(s) of one or more peripheral       tions) were considered to have PTS, by
findings of PTS in the radiologic litera-       nerves originating from the brachial         consensus between the two authors, on
ture is probably related to the fact that      plexus (1,7). The purpose of our study       the basis of the referring clinician’s final
fat suppression (ie, edema-sensitive se-       was to review retrospectively the MR         diagnosis, the clinical history, the phys-
quencing) did not become a routine part        findings and clinical information of the      ical examination results, the MR find-
of shoulder MR imaging protocols until         patients with PTS that we have seen.         ings, and the electromyographic results.
the middle 1990s.                                                                               We also examined the data of an
     Acute brachial neuritis was recog-                                                     additional six patients with PTS (one
nized as a distinct clinical entity when        Materials and Methods                       with bilateral involvement) that were
Spillane (3) reported on 46 patients in        Our institutional review board did not       obtained by means of imaging consulta-
1943. In 1948, Parsonage and Turner            require its formal approval or informed      tions from outside facilities during the
(2) reported on a series of 136 patients       patient consent at the time of the study.    same time period. The MR imaging for
with a similar condition that they called      However, the study was Health Insur-         these six patients was performed at the
neuralgic amyotrophy or shoulder-gir-          ance Portability and Accountability Act      various referring institutions. Thus, our
                                               compliant.                                   study group comprised 27 patients (18
                                                                                            male, nine female; age range, 12– 81
 Advances in Knowledge                         Patient Selection                            years; mean age, 41 years) with PTS,
      Of 30 shoulders examined with            We retrospectively reviewed the infor-       three of whom had bilateral involve-
      MR imaging in patients with Par-         mation in a computerized database of
      sonage-Turner syndrome, 29               2875 consecutive shoulder MR exami-
                                                                                            Published online
      (97%) had involvement of the su-         nations performed at our institution
                                                                                            10.1148/radiol.2402050405
      prascapular nerve and 15 (50%)           during a 64-month period (April 1997
      had involvement limited to this          through July 2002). During this period,      Radiology 2006; 240:501–507
      nerve.                                   the MR images from these examinations        Abbreviation:
      Of 30 shoulders examined, 15             were interpreted by six different attend-    PTS Parsonage-Turner syndrome
      (50%) had involvement of the ax-         ing musculoskeletal radiologists. We
                                                                                            Author contributions:
      illary nerve; however, involve-          searched the database by using the key       Guarantors of integrity of entire study, C.M.G., C.A.H.;
      ment was limited to this nerve in        terms Parsonage, Turner, PTS, neuri-         study concepts/study design or data acquisition or data
      only one (3%) shoulder.                  tis, and neurogenic edema. With use of       analysis/interpretation, C.M.G., C.A.H.; manuscript drafting
      Of 30 shoulders examined, one            this set of key terms, we expected to        or manuscript revision for important intellectual content,
      (3%) had involvement of the up-          identify all or nearly all potential cases   C.M.G., C.A.H.; manuscript final version approval, C.M.G.,
      per and lower subscapular nerves         of PTS. The database software identi-        C.A.H.; literature research, C.M.G.; clinical studies,
                                                                                            C.M.G., C.A.H.; and manuscript editing, C.M.G., C.A.H.
      (in addition to involvement of the       fied 81 examinations performed in 79
      suprascapular and axillary nerves).      patients, two of whom underwent bilat-       Authors stated no financial relationship to disclose.


502                                                                                                   Radiology: Volume 240: Number 2—August 2006
MUSCULOSKELETAL IMAGING: MR and Clinical Findings of Parsonage-Turner Syndrome                                                  Gaskin and Helms




ment, who underwent a total of 30             time msec/echo time msec]) with fre-        tients’ electromyography reports. We
shoulder MR examinations. They un-            quency-selective fat saturation, sagittal   reviewed the conclusions of the electro-
derwent MR imaging 3 days to 1 year           oblique T1-weighted spin echo (400 –        myography reports to correlate them
(average, 3 months) following the onset       650/8 –20), and coronal oblique inter-      with the clinicians’ impressions and le-
of their symptoms. Three of these 27          mediate weighted (2000 –3200/20 –30).       sion localizations.
cases were previously reported in the         Additional technical details are as fol-         We also collected data regarding the
literature (1).                               lows: echo train length of eight for the    concomitant MR findings in the 21 pa-
                                              fast spin-echo sequences and a section      tients (23 examinations) who were
Diagnosis                                     thickness of 4 mm, an intersection gap      treated at our institution. We reviewed
No test can be used to diagnose PTS           of 1 mm, a field of view of 16 cm, and a     all patients’ clinical histories specifically
specifically. Both electromyograms and         matrix of 256      192 pixels for all se-   for data regarding pain, weakness,
MR images must be interpreted with            quences. The outside facility examina-      trauma or substantial recent physical
consideration of the clinical history. In     tions were performed at six different       activity, and history of neck and/or
our study, the diagnosis of PTS was           institutions by using varying protocols.    spine evaluation. Because of previously
made when (a) MR imaging revealed             However, they all included at least one     reported clinical associations, we also
within the muscle tissue a high T2 signal     edema-sensitive sequence: either short-     recorded data regarding recent surgery,
intensity abnormality distributed in a        tau inversion-recovery imaging or fast      vaccination, and febrile illness from the
pattern consistent with that of a periph-     spin-echo T2-weighted imaging with fat      patients’ computerized medical records.
eral nerve lesion, (b) the clinical find-      saturation.                                 In addition, we reviewed the given clini-
ings, including no history of trauma or                                                   cal diagnoses associated with the 2875
excessive overhead activity, suggested        Data Collection                             consecutive shoulder MR examinations
the diagnosis of PTS, (c) MR imaging          The 27 patients’ MR examination (n          that were made before the patients un-
revealed the absence of a morphologic         30) results were reviewed by both au-       derwent imaging, as well as the final
cause of the denervation (eg, entrap-         thors in consensus. At the time of con-     clinical diagnoses.
ment neuropathy caused by a mass),            sensus review, the authors had 25
and (d) no other diagnosis was offered        (C.A.H.) and 4 (C.M.G.) years experi-
by the clinicians.                            ence with musculoskeletal MR imaging.        Results
     All 27 patients demonstrated a neu-      The neurogenic high T2 signal intensity
rogenic high T2 signal intensity abnor-       abnormality (ie, diffuse high T2 signal     Nerve Involvement
mality at MR imaging and reported hav-        intensity throughout muscle) and atro-      Of the 30 shoulders examined in 27 pa-
ing shoulder pain, which was acute in 18      phy patterns seen at each examination       tients, 29 (97%) had a pattern of neuro-
and chronic in nine patients. In addi-        were noted by consensus between both        genic high T2 signal intensity abnormal-
tion, all of these patients either re-        authors. Muscles were considered to be      ity (Table) that indicated involvement of
ported having shoulder weakness or            atrophied when they had gross volume        the suprascapular nerve. Fifteen of the
were found to have shoulder weakness          loss and increased fat content relative     30 shoulders had involvement limited to
at physical examination. Eleven (41%)         to the adjacent muscles. Morphologic        this nerve only (Fig 1).
of the 27 patients underwent electro-         causes (eg, a suprascapular ganglion) of
myography, at which all of them demon-        the neurogenic high T2 signal intensity
strated neuropathies that matched or          abnormality that might mimic PTS at
nearly matched the patterns of neuro-         MR imaging were confirmed to be ab-             Distribution of Neuropathy in 30
genic high T2 signal intensity abnormal-      sent by consensus between the authors.         Shoulders
ity seen on the MR images.                    There were no discrepancies regarding                                                 No. of
                                              these findings between our image inter-         Neuropathy Distribution                Shoulders*
MR Imaging Technique                          pretations and the original diagnostic
                                                                                              Suprascapular nerve
MR imaging was performed with a 1.5-T         reports.
                                                                                                 involvement                        29 (97)
magnet (Signa; GE Medical Systems,                We used the pattern of neurogenic
                                                                                              Isolated suprascapular nerve
Milwaukee, Wis) and a commercially            high T2 signal intensity abnormality on
                                                                                                 involvement                        15 (50)
available transmit-receive shoulder coil.     MR images to determine which nerves
                                                                                              Axillary nerve involvement            15 (50)
Patients were placed in the supine posi-      were involved. We then compared our             Isolated axillary nerve
tion, with the shoulder in external rota-     MR findings with the electromyographic              involvement†                         1 (3)
tion. Images were obtained in the trans-      results, when available (for 11 of 27 pa-       Subscapular nerve
verse, coronal oblique, and sagittal          tients). Specifically, both authors com-            involvement                          1 (3)
oblique planes. Pulse sequences in-           pared the distributions of muscular high
cluded transverse, coronal oblique, and       T2 signal intensity abnormality seen on        * Numbers in parentheses are percentages.
                                                                                             †
                                                                                               There was suprascapular and axillary nerve involve-
sagittal oblique T2-weighted fast spin        the MR images with the distributions of
                                                                                             ment on the contralateral side.
echo (3000 – 4083/60 –105 [repetition         denervation injury described in the pa-

Radiology: Volume 240: Number 2—August 2006                                                                                                      503
MUSCULOSKELETAL IMAGING: MR and Clinical Findings of Parsonage-Turner Syndrome                                                              Gaskin and Helms




    The axillary nerve was involved in                  scapular and axillary nerves. One shoul-             the onset of her symptoms with the
15 (50%) of the 30 shoulders (Figs 2                    der (3%) had involvement of the sub-                 birth of her son (in an otherwise uncom-
and 3). However, involvement was lim-                   scapular nerves—specifically, the upper               plicated spontaneous vaginal delivery).
ited to this nerve in only one (3%)                     and lower subscapular nerves innervat-                    Multiple concomitant findings were
shoulder (Fig 4); this patient also had                 ing the subscapularis muscle—in addi-                appreciated at the 23 shoulder MR ex-
contralateral involvement of the supra-                 tion to suprascapular and axillary nerve             aminations performed in 21 patients
                                                        involvement (Fig 5).                                 (two of whom underwent bilateral
                                                                                                             tests) at our institution, who ultimately
 Figure 1                                               Side-based Atrophy                                   received a diagnosis of PTS. According
                                                        Sixteen (59%) of the 27 patients had                 to the MR image interpretations (not
                                                        PTS involvement limited to the right                 surgical correlations), these findings
                                                        side; eight (30%), involvement limited               were as follows: rotator cuff tear at two,
                                                        to the left side; and three (11%), bilat-            rotator cuff tendinosis at six, acromio-
                                                        eral involvement. Nine (30%) shoulders               clavicular joint abnormality at 14, bi-
                                                        were noted at MR imaging to have mus-                ceps tendon abnormality at three, de-
                                                        cular atrophy distributed in a pattern               generative labra without discrete tears
                                                        similar to that of the neurogenic high T2            at three, and subacromial-subdeltoid
                                                        signal intensity abnormality (Figs 2b                bursitis at nine examinations. Several of
                                                        and 4b). Eleven (41%) patients under-                these examinations revealed more than
                                                        went electromyography also, and all of               one abnormality.
                                                        them demonstrated neuropathies that                       Fourteen of the 2875 consecutive
                                                        matched or nearly matched the patterns               shoulder MR examinations performed
 Figure 1: Isolated involvement of suprascapu-          of neurogenic high T2 signal intensity               at our institution were requested specif-
 lar nerve. Sagittal oblique T2-weighted fast spin-     abnormality seen on the MR images.                   ically for evaluation of possible PTS.
 echo MR image (4000/75) with fat saturation                                                                 The findings of four of these examina-
                                                        Additional Data                                      tions (ordered by three different ortho-
 (anterior region is to the left) shows high signal
 intensity throughout supraspinatus (SS) and in-        Two (7%) of the 27 patients were                     pedists) actually confirmed the clinical
 fraspinatus (IS) muscles compared with normal          known to have had recent febrile ill-                diagnosis. Of the 10 remaining MR ex-
 signal intensity throughout teres minor (TM)           nesses. Two others (7%) developed                    aminations, one had normal results. Of
 muscle.                                                symptoms after surgical procedures and               the other nine examinations, six had
                                                        anesthesia. Another patient associated               findings suggesting acromioclavicular
                                                                                                             joint abnormality; two, findings suggest-
                                                                                                             ing rotator cuff tear; one, findings sug-
                                                                                                             gesting superior labral anteroposterior
 Figure 2                                                                                                    tear; one, findings suggesting isolated
                                                                                                             supraspinatus atrophy without rotator
                                                                                                             cuff tear; and one, findings suggesting
                                                                                                             rhomboid atrophy. Several of these ex-
                                                                                                             aminations revealed more than one ab-
                                                                                                             normality. The findings of these 10 ex-
                                                                                                             aminations could have represented ra-
                                                                                                             diologically occult PTS (because imaging
                                                                                                             was performed too early or too late), or
                                                                                                             they may have simply represented other
                                                                                                             abnormalities clinically mimicking PTS.
                                                                                                                  Six of the 27 patients reported hav-
                                                                                                             ing participated in nontraumatic moder-
                                                                                                             ate physical activity the day before the
                                                                                                             onset of their symptoms. None of these
                                                                                                             activities involved violent overhead mo-
                                                                                                             tion.
 Figure 2: Involvement of suprascapular and axillary nerves. (a) Sagittal oblique T2-weighted fast spin-          Eight of the 21 patients with PTS
 echo MR image (3000/78) with fat saturation (anterior region is to the left) shows high signal intensity    who were treated at our institution also
 throughout supraspinatus (SS), infraspinatus (IS), and teres minor (TM) muscles. (b) Sagittal oblique T1-
                                                                                                             underwent cervical spine MR examina-
 weighted spin-echo MR image (600/20) shows mild fatty atrophy of supraspinatus, infraspinatus, and teres
                                                                                                             tions, which yielded the following re-
 minor muscles.
                                                                                                             sults: One examination revealed normal

504                                                                                                                 Radiology: Volume 240: Number 2—August 2006
MUSCULOSKELETAL IMAGING: MR and Clinical Findings of Parsonage-Turner Syndrome                                                                         Gaskin and Helms




  Figure 3                                             Figure 4




  Figure 3: Involvement of suprascapular and
  axillary nerves. Coronal oblique T2-weighted fast    Figure 4: Isolated involvement of axillary nerve in patient with contralateral involvement of suprascapular
  spin-echo MR image (4083/63) with fat saturation     and axillary nerves. (a) Sagittal oblique T2-weighted fast spin-echo MR image (3000/78) with fat saturation
  shows high signal intensity throughout supraspi-     (anterior region is to the left) shows high signal intensity involving teres minor (long arrow) and deltoid (short
  natus (SS) and deltoid (D) muscles.                  arrows) muscles. (b) Sagittal oblique T1-weighted spin-echo MR image (650/15) (anterior region is to the
                                                       left) shows focal fatty atrophy of teres minor muscle (arrows) compared with normal supraspinatus (SS), in-
                                                       fraspinatus (IS), and subscapularis (Sub) muscles.
findings; six examinations, mild broad-
based disk bulges from C3– 4 to C5– 6
(one with right-sided C3– 4 neurofo-                  increased capillary blood volume in par-                    Predisposing anatomic conditions may
raminal narrowing); and one examina-                  tially denervated muscle. They also re-                     include a thick or calcified superior
tion, moderate central canal stenoses at              ported high T2 signal intensity abnor-                      transverse scapular ligament, the pres-
C3-4 and C4-5 due to broad-based disk                 mality within muscle at only 48 hours                       ence of an anterior coracoscapular liga-
bulges (with severe bilateral C4 –5 neu-              following the denervation insult. Neuro-                    ment, a narrow spinoglenoid or supras-
roforaminal narrowing). One of the pa-                genic high T2 signal intensity abnormal-                    capular notch, and a hypertrophied sub-
tients evaluated with cervical spine MR               ity in and of itself is not specific for PTS.                scapularis muscle (which may cover the
imaging had bilateral nerve involvement               The high signal intensity has other                         anterior aspect of the suprascapu-
at shoulder MR imaging. This patient                  causes, such as trauma, entrapment                          lar notch) (15–17). These conditions
had normal cervical spine examination                 neuropathy due to local mass effect (eg,                    are generally managed nonsurgically—
results, with the exception of a mild                 a ganglion in the suprascapular notch),                     there is limited surgical correlation in
C5– 6 disk bulge that caused mild cen-                and herniated cervical disks (1,7,13).                      the literature (15–18)—and may mimic
tral stenosis without foraminal narrow-               Quadrilateral space syndrome also can                       PTS at imaging. However, when they
ing. The spinal cord was normal in this               mimic PTS, although it typically has an                     do, they generally have a different clini-
case.                                                 insidious onset and involves the axillary                   cal presentation and do not have axil-
                                                      nerve only (7,14).                                          lary or subscapular nerve involvement.
                                                           Suprascapular neuropathy also has                          The diagnosis of PTS is suggested
  Discussion                                          been reported as an uncommon chronic                        when there is an abnormality of the
The MR findings of PTS are thought to                  lesion related to a combination of pre-                     muscles that are innervated by the bra-
reflect denervation injury (1,7). It has               disposing anatomic conditions and                           chial plexus, without a history of trauma
been shown that following an acute neu-               chronic excessive overhead sports ac-                       or excessive overhead activity or a mor-
rologic insult, denervated muscle ini-                tivities (particularly volleyball and less                  phologic cause identified at MR imaging
tially appears normal. Early study (9–                particularly baseball pitching). This                       (7). Other causes of high T2 signal in-
11) results demonstrated increased T2                 neuropathy typically presents in ath-                       tensity abnormality within muscle, such
signal intensity within the affected mus-             letes who perform high-level overhead                       as myopathy, myositis, and tumor, also
cles within 2 weeks after the denerva-                sports and have painless infraspinatus                      should be excluded on the basis of imag-
tion; the investigators concluded that                atrophy (nerve involvement around the                       ing findings and/or the clinical history.
the signal intensity increase was due to              spinoglenoid notch). More proximal                              It is unknown how often PTS mani-
increased extracellular water content.                nerve involvement (around the supras-                       fests in the absence of positive MR find-
More recently, Wessig et al (12) con-                 capular notch) will include the supraspi-                   ings. Given prior experiments that re-
cluded that the increased T2 signal in-               natus muscle as well and might include                      vealed initially normal-appearing mus-
tensity was more likely to be related to              more pain fiber involvement (15–18).                         cle following acute denervation and the

Radiology: Volume 240: Number 2—August 2006                                                                                                                            505
MUSCULOSKELETAL IMAGING: MR and Clinical Findings of Parsonage-Turner Syndrome                                                    Gaskin and Helms




onset of muscular high T2 signal inten-                  The current thinking—although it          axillary nerves—individually or com-
sity abnormality within 2 weeks (9–11),              has changed little since 1972—is that         bined—reportedly have been the most
we speculate that MR findings might be                PTS is a manifestation of a systemic or       commonly affected, according to clinical
falsely negative when the examination is             localized infectious or immunologic dis-      evaluation and electromyographic find-
performed early (perhaps within 2                    order (1,5–7,19). Tsairis et al (4) re-       ings (1–6). In our study, the suprascap-
weeks after the onset of symptoms).                  ported that a systemic viral infection        ular nerve was almost invariably in-
However, a more recent study revealed                preceded the onset of symptoms in as          volved (in 97% of shoulders), and the
subtle high T2 signal intensity abnor-               many as 25% of the patients in their          axillary nerve was involved in 50% of
mality within muscle at only 48 hours                study. In the same series, up to 15% of       shoulders. The long thoracic nerve was
following denervation injury in a con-               the patients reportedly received recent       not found to be involved in any shoul-
trolled experimental environment (12).               vaccinations prior to their initial pre-      ders in this series; however, this nerve
     PTS classically presents with a sud-            sentations. Two (7%) of the 27 patients       innervates the serratus anterior muscle,
den onset of intense shoulder pain with-             in our series had recent febrile illnesses.   which is not well evaluated at routine
out an apparent cause followed shortly               Epidemiologic clustering of outbreaks of      shoulder MR imaging because it is
thereafter by substantial local weak-                PTS in association with antecedent viral      largely excluded from the field of view.
ness. Typically, the pain subsides over a            or febrile illness has been reported in       The subscapular nerve was involved in
period of weeks to months, but the                   Czechoslovakia (20) and in an American        one shoulder (3%) in this series.
weakness may worsen during this time.                Indian population in the southwestern             Eleven (41%) patients underwent
The long-term prognosis is good: The                 part of the United States (21).               electromyography, at which they all
disorder is self-limited, with gradual re-               Prior reports have shown associa-         demonstrated neuropathies and plex-
covery usually occurring within months               tions of PTS with recent surgery and          opathies that matched or nearly matched
(1–6). Some patients, however, may ex-               anesthesia and with childbirth (1–5,22).      the patterns of neurogenic high T2 signal
perience persistent weakness for at                  Two (7%) of our study patients had re-        intensity abnormality seen at MR imag-
least 8 years (5). Tsairis et al (4) noted           cently undergone surgery and anestheti-       ing. Given that only one or two nerves
excellent recovery in 80% of patients by             zation, while another patient (4%) asso-      were involved in most of our cases, PTS
2 years and in 90% of patients by 3                  ciated the onset of her symptoms with         may actually be a mononeuropathy or
years. In general, patients with more                the otherwise uncomplicated vaginal           polyneuropathy rather than a true plex-
severe initial symptoms are more likely              birth of her son.                             opathy.
to have a protracted course (2).                         A genetic component might predis-             PTS is often confused clinically with
                                                     pose an individual to PTS: A clinically       more well-known and common disor-
                                                     similar but distinct inherited disorder       ders such as cervical spondylosis, rota-
 Figure 5
                                                     called hereditary neuralgic amyotrophy        tor cuff tear, shoulder impingement
                                                     has been described. This autosomal            syndrome, and acute calcific tendonitis
                                                     dominant disorder is characterized by         (1,5,6,19). Therefore, knowledge of
                                                     recurrent, episodic, painful brachial         PTS and its characteristic imaging find-
                                                     neuropathy in association with mild dys-      ings may enable the radiologist to be the
                                                     morphic features (23).                        first to suggest the correct diagnosis
                                                         PTS has been reported in patients         while helping to avert inappropriate
                                                     ranging in age from 3 months to 74            therapy or even unnecessary surgery.
                                                     years, with the majority of cases being       Treatment of PTS is nonoperative and
                                                     evenly distributed among patients in the      typically consists of analgesia coupled
                                                     3rd–7th decades of life. In the two larg-     with physical therapy (1,19).
                                                     est (to our knowledge) clinical series of         Our study had limitations. In gen-
                                                     patients with PTS, a male-to-female ra-       eral, the study was limited by its retro-
                                                     tio of approximately 2:1 was observed         spective nature. Also, there was selec-
                                                     (2,4). Our imaging study involved pa-         tion bias: The original imaging reports
                                                     tients of a similar age range (12– 81         of the patients chosen for the study de-
 Figure 5: Involvement of subscapular, supras-       years) and a similar male-to-female ra-       scribed specific findings that were iden-
 capular, and axillary nerves. Sagittal oblique      tio (2:1). Similar to the 10%–20% of          tified by using a key term word search.
 short-tau inversion-recovery MR image (5000/70/     patients with bilateral PTS in the two        Owing to the use of this restrictive entry
 150 [repetition time msec/echo time msec/inver-     large clinical series (2,4), three (11%)      criterion, which led to the exclusion of
 sion time msec]) (anterior region is to the left)   of the 27 patients in our study had bilat-    patients with PTS whose original imag-
 shows marked and increased signal intensity         eral PTS.                                     ing reports did not include our specific
 throughout subscapularis (Sub), supraspinatus
                                                         PTS may involve multiple nerves           search terms, the occurrence of PTS
 (SS), infraspinatus (IS), and teres minor (TM)
                                                     originating from the brachial plexus.         within our study population may have
 muscles.
                                                     The long thoracic, suprascapular, and         been underestimated. It is also possible

506                                                                                                       Radiology: Volume 240: Number 2—August 2006
MUSCULOSKELETAL IMAGING: MR and Clinical Findings of Parsonage-Turner Syndrome                                                   Gaskin and Helms




that some patients with PTS may have          first to suggest the correct diagnosis and           12. Wessig C, Koltzenburg M, Reiners K, Soly-
been excluded owing to the lack of posi-      subsequently affect both the prognosis                  mosi L, Bendszus M. Muscle magnetic
                                                                                                      resonance imaging of denervation and
tive MR findings. Some positive-result         and the treatment.
                                                                                                      reinnervation: correlation with electro-
examinations may have gone unrecog-                                                                   physiology and histology. Exp Neurol 2004;
nized at the time of initial interpretation                                                           185:254 –261.
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Radiology: Volume 240: Number 2—August 2006                                                                                                    507

				
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