Suprascapular Nerve

Anatomy

 

C5, 6 from Upper trunk

 

Posterior triangle

- arises upper trunk and passes backward through posterior triangle

- under belly of omohyoid

- deep to trapezius to the suprascapular notch

 

Suprascapular Ganglion Coronal MRI

 

Runs through suprascapular notch

- under superior transverse scapular ligament

- suprascapular artery and vein run over this ligament

- supplies SS 1 cm after passing under ligament

- give articular branch to the shoulder

 

Suprascapular Nerve Sagittal MRI 1Suprascapular Nerve Sagittal MRI 2

 

Passes around lateral border spinous process / Spinoglenoid notch

- under spinoglenoid ligament

- inferior transverse scapular ligament

- supplies IS

 

Motor

-  supplies supraspinatus & infraspinatus

 

Sensory

- ACJ, GHJ

- CA and CH ligaments

 

Sites of Compression / Injury

 

Suprascapular notch

- weakness wasting SS & IS

 

Causes

- trauma most common / driect blow / clavicle or scapula fracture

- iatrogenic / excessive rotator cuff release

- athletes / repetitive overhead motion

 

Spinoglenoid notch

- weakness wasting IS

 

Causes

- spinoglenoid cyst associated with superior labral tear / horizontal cleavage / acts as one way valve

- posterior approach to shoulder - > 1 cm medial to glenoid neck

- posterior shoulder OA causing a cyst

 

History

 

Pain at back of shoulder

Weakness

 

Examination

 

Weakness

 

Atrophy SS/IS

 

Atrophy of IS alone

 

DDx

 

Rotator Cuff tear

 

MRI 

 

1.  Spinoglenoid cyst / labral tear

- may be better seen with MRA

 

Spinoglenoid cyst Coronal MRISpinoglenoid Cyst Sagittal MRISpinoglenoid Cyst MRI Axial

 

2.  Atrophy of SS / IS

 

Spinoglenoid Cyst Infraspinatous Fatty Atrophy

 

3.  Exclude cuff tear

 

EMG 

 

Demonstrate denervation SS/IS or IS alone

 

HCLA

 

Inject SS nerve at suprascapular notch

 

Management

 

Non Operative

 

Reasonable if no ganglion cyst

- a neuropraxia which usually resolves

- avoid overhead activities if possible

- 6 - 9 months

 

Operative

 

Spinoglenoid Cyst

 

1.  Secondary to superior labral tear

 

Majority of cases

  

A.  Cyst Decompression + Arthroscopic labral repair

 

Technique

- identify horizontal cleavage tear

- decompress throught tear

- repair labrum

 

Posterior Labral Tear Cyst 1Posterior Labral Tear Cyst 2Posterior Labral Tear Cyst 3

 

Posterior Labral Tear 1Posterior Labral Repair 2Posterior Labral Tear 3

 

Piatt et al J Should Elbow Surg 2002

- excellent results

 

B.  Arthroscopic Labral Repair without cyst decompression

 

Schroder et al JBJS Am 2008

- 42 patients

- posterior labral repair without cyst decompression

- cyst resolved in 88% on MRI and smaller in remainder

- all patients satisfied with outcome

 

2.  Spinoglenoid Cyst without labral tear

 

Options to decompress cyst

- ultrasound drainage / not always effective but may be worth a try intially

- posterior approach

- arthroscopic glenohumeral approach / posterior capsulotomy

- subacromial approach / between supraspinatous and infraspinatous

 

Results

 

Werner et al Arthroscopy 2007

- posterior capsulotomy above IGHL with decompression of cyst with shaver

 

Posterior Shoulder Capsulotomy to decompress cyst

 

Ghodadra et al Arthroscopy 2009

- subacromial space

- identify spine of scapula

- dissect between infraspinatous and supraspinatous

- accessory posterior portal, retract IS and nerve

- decompress with shaver

 

Shoulder Subacromial Space Spinous ProcessSubacromial Spinous Process 1

 

Suprascapular Notch Impingement

 

Decompression / Division of Suprascapular ligament 

 

Indication

- weakness atrophy of SS and IS without cuff tear

- massive irreparable cuff tear with intractable pain

 

Options

- open

- arthroscopic

 

Results

 

Lafosse et al Arthroscopy 2007

- 10 patients with clinical and EMG evidence of suprascapular nerve compression

- no complications

- good clinical outcome in all patients

 

Open Technique

- incision along spine of scapular

- sharply elevate trapezius off spine off scapula

- SS reflected inferiorly to expose notch

- preserve superior NV bundle

- suprascapular artery lies above ligament, (branch of Subclavian Artery)

- divide ligament

 

Arthroscopic Technique

 

Standard posterior portal

- subacromial portal to debride cuff and identify base of coracoid as landmark

- find coracoid by following CAL to it

- feel hard bony prominence

 

Anterolateral working portal

- need to be able to work lateral to medial along anterior aspect of humeral head

 

Dissection

- clear space medial to coracoid along subscapularis

- identify the conoid ligament attaching to the base of the coronoid

- medial to this is fatty area with THL

 

SSN Release CoracoidSSN Release Coracoid and CHL

 

Suprascapular portal / accessory Nevasier

- 7cm from posterior edge of acromion

- insert blunt instruments posteriorly from suprascapular portal

- pass under clavicle

- elevates supraspinous muscle

- use blunt trochar to dissect area

 

Anatomy

- will usually see the artery passing over the top of the THL 

- be careful as this runs from subclavian

- can get torrential bleeding

 

Conoid Ligament  SSA over THLSuprascapular artery and transverse scapula ligament

 

Identify transverse ligament

- identify SSN passing under

- divide TSL with scissors from posterior ACJ portal

- whilst retracting SS artery with probe from SSN portal

 

SSN release Divided THLSSN Release Divided TSL