The Role of Suprascapular Nerve Decompression

Jeremy Granville-Chapman

Upper Limb Fellow

Aims

• Epidemiology

• Anatomy

• Aetiology

• Diagnosis

• Management Options

• Techniques for decompression

• Some evidence

Epidemiology

• Incidence unknown • Relatively uncommon • 1959-2001 only 88 reported cases • By 2011, largest case series 53 pts • Seems to have bimodal age distribution

– Overhead athletes/ sporting injury – 50s and older +/- rotator cuff tears

• Isolated infraspinatus involvement more common in younger patients

• Suprascapular notch more common with cuff tear

Anatomy

• Upper trunk brachial plexus

• C4 C5 C6

• Passes beneath superior transverse scapula ligament

• Wraps around spinoglenoid notch

• Motor branches into Supra and Infra

• First of 2 branches to supra arises in notch

Aetiology

• Overhead sport – Possibly SGL hypertrophy alongside GIRD – SGL blends with post capsule

• Trauma – clavicle fracture, dislocation, SLAP tear – (EMG changes in 29% prox humeral #/dislocations)

• Tumour • Ganglion with SLAP tear • Retracted rotator cuff tear • Narrow ossified notch • Surgery – SLAP repair anchors, Latarjet screw

XS study of 84 pro-volleyball 30% incidence infraspinatus atrophy 1

1. Lajtai G et al. The shoulders of professional beach volleyball players: High prevalence of infraspinatus muscle atrophy. Am J Sports Med 2009; 37(7):1375-1383

Diagnosis • History and Exam

– dull poorly localised ache and weakness, made worse with overhead activity. Wasting and weakness

• XR/CT • MRI

– Ganglion with SLAP – degree wasting of muscles – Rotator cuff tear

• EMG – Fibrillations, reduced amplitude – Can help localise site of compression proximal or distal – Excludes more generalized plexopathies – Predicts outcome with surgery?

Space Occupying Lesion & EMG

changes

Overuse/Non Compressive

lesion

Address cause (SLAP repair) +/-

decompress ganglion/SSN

Conservative Rx

NSAIDS, avoidance Capsular

stretching

Young athlete

Series1: 15 pts

Good/excellent 12/15

3 needed surgery – with mixed

results

1. Martin SD et al. Suprascapular neuropathy: Results of non-operative treatment. JBJS(Am) 1997;79(8):1159-1165 2. Piatt BE et al. Clinical evaluation and treatment of spinoglenoid notch ganglion cysts. JSES 2002;11(6):600-604 3. Antoniou et al. (Iannotti). Suprascapular neuropathy: variability in the diagnosis, treatment and outcome. Clin Orthop

Relat Res 2001;386:131-138

Series2: 46 pts total

Surgery - 26/27 pts satisfied Non-operative - 10/19 satisfied

Decompress nerve?

Conservative as good as (open) surgery in non-

compressive lesions3

SLAP patients - do we need to aspirate the ganglion or decompress the nerve

if repairing a SLAP tear?

10 patients with SGN ganglion and SLAP tears All underwent SLAP repair only

4/10 with pre-op EMG underwent post-op: EMG normalized 8/10 had post-op MRI: all had complete cyst resolution

1. Youm T et al. Treatment of patients with spinoglenoid cysts associated with superior labral tears without cyst aspiration, debridement or excision. Arthroscopy 2006;22(5:548-552

SSN in older patients without cuff tear or compression

Lafosse 2007 Shah 2011

• 10 pts (Age 50)

• EMG +ve chronic comp.

• Arthroscopic release

• 15 mth f/u Improved: • EMG 7/8 complete recovery

• Constant score

• Strength AB/ER

• 9/10 excellent with

• complete pain relief

• 27 pts (Age 49) • 24/27 +ve EMG • Arthroscopic release • 22 mth f/u Improved:

• VAS 17/24 • SSV 17/24 • ASES 18/24 • No post-op EMG

Neuropathy and Rotator cuff tear – why does it happen?

• Supraspinatus supplied by only two motor branches

– Proximal branch dominant

– Branch arises in notch in 9/12 cadavers 2

– Normal angle is 142 degrees

– Retraction kinks this branch

– All motor branches taught at 2-3cm retraction

2. Abritton MJ et al. JSES 2003; 12(5):497-500c

1cm

142 °

98 °

35 °

Normal

5 cm

Does reduction of retracted tears threaten the SSN?

Warner JP, Gerber C et al. Anatomy and relationships of the suprascapular nerve: Anatomical constraints to mobilization of the Supraspiantus and Infraspinatus muscles in the management of rotator cuff tears. JBJS (Am) 1992;74:36-45

• Cadaveric study

• Suggests risk of SSN traction injury with reduction >3cm of supraspinatus, BUT..

SSN recovers with repair of MCT

Costouros 2007 3

• 26 MCT. Retraction, fatty change and weakness

• 38% had EMG evidence SSN neuropathy (7/26) – (4/26 had Ax neuropathy)

• These 7 pts underwent arthroscopic full or partial repair (unachievable in 1)

• Post op EMG in 6 repairs – full nerve recovery

• Complete pain relief • Increased function

Mallon 2006 4

• 8pts. 5cm MCT, retraction, fatty change, EMG+, active FE<40 degrees

• 4 no surgery: no improvement 2yr

• 4 mini-open partial repair and convergence:

– 2 of 4 had post-op EMG partial/near complete recovery

– 4 of 4, >90 degrees FE, hand behind head

3. Costouros JG (Warner JJ) et al. Reversal of suprascapular neuropathy following arthroscopic repair of massive supra and

infra rotatior cuff tears. Arthroscopy 2007;23(11):1152-1161 4. Malllon WJ et al. The association of suprascapular neuropathy with massive rotator cuff tears: a preliminary report.

JSES 2006;15(4):395-398

So, do we need to release nerve at same time as MCT repair?

• No comparative studies I could find • A few reports of pain and EMG dysfunction

after RC repair (Lafosse cites 3 patients in 2007 paper), but..

• Several series show improvement in nerve function after MCT repair

• …probably not, but would EMG pts if sig. pain and weakness remain post RC repair

Options with cuff tear and SS Neuropathy?

• Attempt repair/partial repair, if not..

• Consider decompressing nerve at STSL

• OR.. Consider ablation ..

Irreparable MCT/CTA: Nerve Ablation

• 57 chronic shoulder pain patients 7

• 480sec ablation PRF

• Shoulder pain verbal numeric rating scale

• >50% pain relief in 74% at 3 mths

• Further 18% <50% improvement, but still relief

• No complications

• 79% still reported improvement at 6 mths

7. Luleci N et al. Evaluation of patients' response to pulsed radiofrequency treatment

applied to the suprascapular nerve in patients with chronic shoulder pain

Back and Musculoskeletal Rehabilitation. 2011; 24(3):189-194

Nerve Ablation - 2

• 12 pts with painful CTA. Mean age 68 8

• PRF ablation

• Constant, Oxford scores improved at 3 and 6 months

• Non sig. improvement VAS which deteriorated between 3-6 months

• Authors conclude useful adjunct in those unfit for surgery

8. Kane TP et al. Pulsed radiofrequency applied to the suprascapular nerve in painful cuff tear arthropathy. JSES 2008;17(3):436-440

• 13 PRF ablations in 11 pts with chronic shoulder pain 9

• 1 month

– 77% had >50% VAS reduction. 7.5 to 2.8

• 6 months

– 69% still enjoyed >50% VAS benefit (mean 2.5)

– Shoulder pain and disability index improved

– 9/11 pts had reduced analgesia regimens

9. Lilang P-C et al. Pulsed Radiofrequency Lesioning of the Suprascapular Nerve for Chronic Shoulder Pain: A Preliminary Report. Pain Medicine 2009; 10(1):70-75

Nerve Ablation - 3

Open Surgical Techniques

• Suprascapular notch4

– Bra strap incision

– Trapezius split

– Supraspinatus retracted posteriorly

• Spinoglenoid notch5

– Vertical incision 3cm medial PL corner acromion

– Deltoid split (care Ax n)

– Infra fascia incised and muscle retracted inferiorly

– Follow inf. border of spine laterally to notch

4. Romeo AA et al. Suprascapular neuropathy. J Am Acad Orthop Surg 1999;7[6]:358-367 5. Piasecki DP (Romeo AA) et al. Suprascapular neuropathy. J Am Acad Orthop Surg 2009; 17(11):665-676

Arthroscopic STSL release

• DeBeer6 and Lafosse7 separately reported techniques in 2006

• Trans-bursal approach + one or two medialized Neviaser portals (7cm from lat edge acromion) for retraction and separation of the STSL – Anterior gutter bursectomy – Follow CA lig to coracoid – Head medially over base of coracoid to CC lig – Just postero-medial to this is the notch – Identify vessel over, nerve beneath and release

ligament

6. Bhatia DN, De Beer JF et al: Arthroscopic suprascapular nerve decompression at the suprascapular notch. Arthroscopy 2006;22(9): 1009-1013

7. Lafosse L et al. Technique for endoscopic release of suprascapular nerve entrapmentat the suprascapular notch. Tech Shoulder Elbow Surg 2006;7:1-6

Arthroscopic SG Notch decompression

Bursal route Articular route

6. Werner CM and Gerber C: Combined intra- and extra-articular arthroscopic treatment of entrapment neuropathy of the infrapinatus…. Arthroscopy 2007;23(3):e1-e3

• Bursectomy and view

• Define scapular spine (keel)

• Accessory posterior portal – Langenbeck retractor to pull infra down to expose cyst and notch from above

• View from anterosuperolateral portal

• Trans-cuff (Wilmington) working portal

• Enter cyst via SLAP tear or above labrum

• Nerve on floor notch medially 2-3cm from biceps anchor

Summary • Overhead athletes

– If space-occupying lesion with wasting/EMG changes, likely to do well with surgery, probably just SLAP repair

– Post capsular programme etc as effective as surgery if no compressive lesion

• SSN neuropathy no tear no compression – If conservative Rx failed, series show decompression at

STSL effective

• Painful Massive Cuff Tear – Consider repair/partial repair

– Surgical decompression at suprascapular notch

– If not possible/not fit, consider ablation via US

Questions?