Suprascapular nerve entrapment

1. Suprascapular Nerve
Entrapment
JBJS Vol.82-A NO.3
JAAOS Vol.7 NO.6

2. Suprascapular Nerve Entrapment
 Shoulder pain and weakness caused by
supra scapular nerve
 Traction injury
 Ganglion cysts or other mass lesions
 1959 → suprascapular neuropathy at the
suprascapular notch. Kopell and
Thompson
 1982 → differentiated suprascapular nerve
entrapment at the spinoglenoid Notch.
Aiello et al

3. Anatomy
anterior aspects of the right shoulder
The suprascapular nerve is shown
originating from the superior trunk of
the brachial plexus.
Posterior aspects of the right shoulder
the suprascapular nerve is passing
beneath the superior transverse scapular
ligament and passing through a narrow
fibro-osseous tunnel formed by the spine of
the scapula and the spinoglenoid ligament

4. Classification of abnormalities of the
suprascapular notch Rengachary
 Type I depression
superior border of the
scapula
 Type II wide, blunted, V-
shaped notch
 Type III symmetrical and
U-shaped notch
 Type IV very small V-
shaped notch
 Type V partial
ossification of the medial
portion of the transverse
scapular ligament
 Type VI completely
ossification of the
transverse scapular
ligament
8% 31% 48%
3% 6% 4%

5. Pathophysiology
 Traction → secondary to repetitive
microtrauma, primarily from overhead
activities (likely at the level of the
suprascapular notch).
 Direct injury to the nerve
 Indirect injury by affecting the vascular
supply to the nerve
 Direct trauma or indirect trauma
 Iatrogenic injury
 Compression by a ganglion cyst or tumor

6. History
 Ages of 20 - 50 years with involvement
of the dominant upper extremity
 Dull aching pain located in the posterior
aspect of the shoulder, and exacerbated
by overhead activities.(Proximal lesions
> distal lesions) may be completely
asymptomatic.
 Weakness of the affected shoulder

7. Physical Examination
 Should consist of a thorough
shoulder, cervical spine, and
neurological evaluation
 Atrophy of the scapular
muscles
 Tenderness
 Proximal lesion
 Distal lesion
 The cross-adduction test →
increased pain
marked atrophy of the
infraspinatus muscle.

8. Diagnostic Studies
 The diagnosis is often one of exclusion.
 Injection of a local anesthetic into the
suprascapular notch → the specificity is
unclear
 Plain radiography → R/O another cause
of shoulder pain
 Ultrasonography → excellent and
inexpensive method to identify ganglion
cysts or other mass lesions

9. Diagnostic Studies
 Electrodiagnostic Studies
(nerveconduction -velocity and
electromyography) → confirm and
localize the lesion
 Suprascapular notch → changes in both the
supraspinatus and the infraspinatus muscle
 spinoglenoid Notch → changes only in the
infraspinatus muscle
invasive and technique-dependent

10. Diagnostic Studies
 CT → evaluate soft-tissue masses
 Ganglion cysts → low or medium attenuation when
compared with the surrounding muscle.
 MRI → best imaging modality for the
assessment of soft-tissue masses about the
shoulder and can detection of intra-articular
lesions
 Ganglion cyst appears as a well defined smoothly
marginated mass
 low signal intensity on T1-weighted images
 high signal intensity on T2-weighted images
 Ring enhancement following the administration of
gadopentetate dimeglumine.

11. Nonoperative Treatment
 Avoidance of activities that result in
trauma and irritation to the nerve.
 Rehabilitation → flexibility, gradual
strengthening of the surrounding
muscles of the glenohumeral joint
 Monitored closely to avoid reinjury to the
nerve
 Ganglion cyst → the results of
nonoperative treatment ↓

12. Operative Treatment
 Localized to the suprascapular notch
 Release of the superior transverse scapular
ligament ± widening of the suprascapular
notch
 Localized to the spinoglenoid notch
 Spinoglenoid ligament
 Scapular spine
 Medial tendinous margin of the rotator cuff

13. Superior approach to the suprascapular
nerve at the scapular notch

14. Operative Treatment
 Secondary to compression by a ganglion
cyst
 Ultrasonography or computed tomography-
guided aspiration of ganglion cysts
 Open and arthroscopic procedures

15. Posterior approach to the suprascapular
nerve at the spinoglenoid notch

16. Shoulder pain and weakness
History and physical examination
Atrophy of rotator cuff
Nontender AC joint
Weakness on external rotation
Negative impingement sign
Positive rotator cuff signs
Positive impingement test
Negative rotator cuff signs
Negative impingement test
Rest, NSAID therapy
Plain films, MR imaging
Rotator cuff
treatment
Neck pain and
radicular symptoms
No neck pain or
radicular symptoms
No evidence of
rotator cuff tear
Evidence of
rotator cuff tear
Cervical spine
treatment
Clinical
reevaluation
Electromyography
Nerve conduction
velocity studies
Rotator cuff
treatment
Evidence of
ganglion cyst
No evidence of
ganglion cyst