A 48-year-old man received a referral to the orthopedic clinic
after failure of a brief trial of conservative therapy for deep,
posteriorly localized shoulder pain, which began 6 months prior to
presentation after a football injury. The shoulder examination was
notable for generalized decreased range of motion secondary to
pain, but no significant signs of instability or rotator cuff tear.
The original radiographs ordered by the patient's primary care
physician were reviewed, and, subsequently, a magnetic resonance
(MR) arthrogram of the shoulder was obtained.
Paralabral cyst associated with posterior labral tear
The radiographs were normal (Figure 1), showing no evidence of
glenohumeral dislocation on the axillary view (not shown). The MR
images revealed a posterosuperior labral tear with an adjacent,
large paralabral cyst (Figure 2) that extended up into the area of
the suprascapular notch (Figure 3), without evidence of
supraspinatus or infraspinatus muscle atrophy.
Paralabral cysts are relatively common incidental findings found on
shoulder MR examinations. They indicate the presence of a nearby
labral tear, although one is not always seen on MR imaging. It is
believed that these cysts are formed following trauma to the
capsulolabral complex, leading to extravasation of synovial fluid,
which accumulates as either a unilocular or multilocular cystic
structure. Paralabral cysts can be classified as synovial cysts,
ganglion cysts, or pseudocysts. Synovial cysts occur through
evagination of the joint capsule and contain a thin synovial cell
lining. Ganglion cysts can arise from ligament, tendon, bone, joint
capsule, or bursa; pseudocysts are fluid-filled structures within
the soft tissues that lack the cellular lining of a true cyst.
Paralabral cysts that occur in the suprascapular notch have been
reported to cause entrapment neuropathies of the suprascapular
nerve alone or both the suprascapular and infrascapular nerves.1
Impingement of the infrascapular nerve by itself can occur if the
cyst is localized to the spinoglenoid notch.2 Larger cysts may
impinge on the axillary nerve and result in teres minor denervation
atrophy, but this is uncommon.3 Patients with paralabral cysts
usually present with chronic, diffuse, and deep postero-lateral
shoulder pain. Radiography will not demonstrate paralabral cysts or
associated capsulolabral injuries. MR imaging findings include a
thin-walled, rounded, sometimes multiloculated hyperintense
structure on T2-weighted imaging that is hypointense on T1-weighted
imaging. Detection of a paralabral cyst should always prompt a
search for an associated labral tear. Electromyographic assessment
and nerve conduction studies are helpful in determining the degree
and site of nerve compression.2 The treatment of paralabral cysts
has traditionally been performed by open surgery, but more
recently, there has been success with arthroscopic cyst excision,
with repair of any associated intra-articular pathology.4 In the
absence of pain, these lesions can be treated conservatively with
rehabilitation and a goal of optimizing shoulder function.
Conclusion: Paralabral cysts are the sequelae of labral tears and
can be detected using a fluid-sensitive MR imaging sequence.
Identification of these structures can lead to prompt, appropriate
treatment and the return of normal shoulder function.
1. Ianotti JP, Ramsey ML. Arthroscopic decompression of a ganglion
cyst causing suprascapular nerve compression. Arthroscopy.
1996;12:739-745. 2. Wong P, Bertouch JV, Murrell AC, et al. An
unusual cause of shoulder pain. Ann Rheum Dis. 1999;58:264-265. 3.
Tung GA, Entzian D, Stern JB, et al. MR imaging and MR arthrography
of paraglenoid labral cysts. AJR Am J Roentgenol.
2000;174:1707-1715. 4. Ferrick, MR, Marzo JM. Ganglion cyst of the
shoulder associated with a glenoid labral tear and symptomatic
glenohumeral instability. Am J Sports Med. 1997;25:717-719.