Suprascapular Nerve

Lennard Funk

‣ Motor innervation: ‣ Supraspinatus & infraspinatus muscles

‣Sensory branches to: ‣ Coracohumeral & coracoacromial ligaments ‣ Subacromial bursa ‣ AC & GH joints

‣Cutaneous innervation: ‣ ? Proximal-lateral one-third of the arm.

Amjani. J Anat. 1994 Horiguchi. J Anat. 1980

Causes

• Idiopathic • Paralabral Cyst / Ganglion • Trauma

Suprascapular Notch

Spinoglenoid Notch

Sites

Natural History

No Cyst Mostly recover in 1yrCyst Less likely to recover

Cummins. JBJS. 2000.

Suprascapular Nerve Palsy• Supraspinatus +/- Infraspinatus

• Wasting • Weakness

Clinical

• Supraspinatus +/- Infraspinatus • Wasting • Weakness

Investigations

• MRI Scan: • Ganglion Cyst / Mass lesion

Suprascapular Spinoglenoid

Electro-diagnostic• EMG + Nerve Conduction Velocities:

• Proximal - Suprascapular Notch • Distal - Spinoglenoid Notch

Nerve Conduction Velocity

‣ From Erb’s point: ‣ Supraspinatus = 2.7 ± 0.5ms ‣ Infraspinatus = 3.3 ± 0.5ms

Kraft. Arch Phys Med and Rehab. 1972

EMG

‣ Increased in denervated muscles: ‣ Spontaneous activity ‣ Fibrillations ‣ Positive sharp waves

‣ Also: ‣ Polyphasic activity ‣ Reduced amplitude of evoked potentials.

Kraft. Arch Phys Med and Rehab. 1972

Note...

‣ After 3 weeks of onset

‣ Operator dependent

‣ Other Periscapular Muscles must be assessed

‣ Repeat studies should be same operator

‣ Discuss!

Treatment

‣ No Cyst - Early decompression appears to show better results (Level 4 studies)

‣Cyst

‣ Aspiration

‣ Open decompression (doesn’t deal with associated pathology)

‣ Arthroscopic Decompression

Aspiration UltrasoundCourtesy of Prof Waqar Bhatti

Arthroscopic Decompression‣ Suprascapular Notch

Position

Portals

1

3

2

4

1 = standard posterior portal

2 = standard anterior portal

3 = anterolateral portal

4 = Nevasier portal

5

5 = Lateral portal

Identify CAL

Identify Coracoid & CCL

Follow Coracoid Base medial to CCL into Scapula Notch

Create Superior (Nevasier) Portal & retract Supraspinatus with probe

Identify Artery & STSL (Superior Transverse Scapular Ligament)

6wks Postop

Spinoglenoid Cyst

Chronic Posterior Shoulder Pain in the Overhead Athlete

‣ Chronic Posterior Pain

‣ Normal EMG & MRI

‣ Exclusion

‣ High index of suspicion

Kevin Plancher

Spinioglenoid Ligament

Summary:

‣ Spinoglenoid / Suprascapular Notch

‣Always get: EMG & MRI

‣ No cyst = Non-operative initially

‣ Cyst = Surgery

‣ Surgery - train on cadaver

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