- Anatomy:
- suprascapular nerve is derived from upper trunk of
brachial plexus, typically receiving fibers from
C5 and
C6;
- it contains both motor and sensory components, and sends sensory branches to both the glenohumeral and AC joints, but does not innervate the skin;
- it passes downward, laterally (deep to the omohyoid and
trapezius & then posteriorly to run under cover of trapezius;
- along with the suprascapular vein and artery, it reaches suprascapular notch;
- the nerve travels beneath the suprascapular notch, where as the vessels travel above the notch;
- after giving off 2 branches to
supraspinatus, it passes around lateral border of the scapular spine (spinoglenoid notch
and ends in the infraspinatus fossa to supply
infraspinatus);
- Suprascapular Nerve Entrapment:
- 2 points of fixation of nerve are at its origin from upper trunk & at suprascapular notch, where it is susceptible to traction injury;
- it is fixed at its origin from
C-5 or upper trunk of
brachial plexus and at its termination in
infraspinatus;
-
compression at the notch:
- may be compressed by either the suprascapular ligament or a cyst (arising from the shoulder joint) which results in paralysis of supraspinatus and infraspinatus;
- following blunt trauma, the ligament may calcify (causing compression);
- compression at the level of the supraspinatus notch would be expected to affect both the
supraspinatus and
infraspinatus;
- may be injured during birth (See
Erbs palsy)
- some recognize that the
supraspinatus tendon & its muscle should not be dissected and elevated from contiguous bone floor for distance exceeding
2 cm medial to superior glenoid rim;
- otherwise, nerve injury and additional weakening of the external rotator muscles could result;
- additional site of iatrogenic injury may occur at the spinoglenoid notch, from instrumentation during rotator cuff repair;
- compression at the level of the spinoglenoid notch would be expected to affect only the
infraspinatus;
-
management:
- patients should have an MRI to rule out an anatomical etiology;
-
EMG is useful to help localize the site of compression;
- w/ nerve compression, expect sharp positive waves, insertional activity, fibrillations, spontaneous rest activity, and decreased recruitment;
- major changes in nerve conductions studies will be variable;
- when an anatomical etiology cannot be found, management should be non operative as most patients will have a good to excellent result with physical therapy;
- physical therapy should emphasize not only the rotator cuff musculature but also all of the muscles that cross the shoulder;
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Suprascapular nerve entrapment . A series of 27 cases.
Suprascapular nerve block. A new approach for the management of frozen shoulder.
Suprascapular nerve entrapment.
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Combined Intra- and Extra-articular Arthroscopic Treatment of Entrapment Neuropathy of the Infraspinatus Branches of the Suprascapular Nerve Caused by a Periglenoidal Ganglion Cyst.
Percutaneous Arthroscopic Release of the Suprascapular Nerve
