Peri-Articular Suprascapular Neuropathy

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Orthopaedics & Traumatology: Surgery & Research 100S (2014) S409–S411

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Review

Peri-articular suprascapular neuropathy

a,∗ b

P. Clavert , H. Thomazeau

Service de chirurgie du membre supérieur, CCOM, CHU de Strasbourg, Strasbourg, France

Service de chirurgie orthopédique et réparatrice, CHU de Rennes, Rennes, France

r t

i c l e i n f o

a b s t r a c t

Article history: Suprascapular nerve entrapment was ﬁrst described in 1959 by Kopell and Thompson. Although rare,

Accepted 2 October 2014

this condition is among the causes of poorly explained shoulder pain in patients with manifestations

suggesting a rotator-cuff tear but normal tendons by imaging studies. Suprascapular nerve entrapment

Keywords: may cause 2% of all cases of chronic shoulder pain. Among the many reported causes of suprascapular

Suprascapular nerve

nerve entrapment, the most common are para-labral cysts, usually in the spinoglenoid notch, and micro-

Compression

trauma in elite athletes. The potential relevance of concomitant rotator-cuff tears remains debated. Less

Ganglion cyst

common causes include tumours, scapular fractures, and direct trauma involving traction. Early diagnosis

Neuropathies

and treatment are crucial to avoid the development of irreversible muscle wasting. Endoscopic surgery

Electrophysiological testing

to treat the various causes of suprascapular nerve compression has superseded open nerve release.

1. Introduction C6, 76%; C4 and C5 and C6, 18%). The nerve travels downwards

and backwards in the neck then enters the shoulder by running

Suprascapular nerve entrapment was ﬁrst described in 1959 by

under the inferior transverse scapular ligament at the suprascapu-

Kopell and Thompson [1]. Although rare, this condition is among

lar notch. The depth of the notch varies widely, and Rengachary

the causes of poorly explained shoulder pain in patients with man-

et al. described six morphotypes [2]. The suprascapular artery trav-

ifestations suggesting a rotator-cuff tear but normal tendons by

els over, and the suprascapular vein under, the inferior transverse

imaging studies [2–4]. Suprascapular nerve entrapment may cause

scapular ligament. The suprascapular nerve then courses through

2% of all cases of chronic shoulder pain.

the supraspinous fossa, under the supraspinatus muscle (3 cm on

Among the many reported causes of suprascapular nerve

average from the rim of the glenoid cavity), to the spinoglenoid

entrapment, the most common are para-labral cysts, usually in the

notch posteriorly, and ends under the infraspinatus muscle in the

spinoglenoid notch [5–8], and microtrauma in elite athletes [9].

infraspinous fossa (2 cm on average from the glenoid rim) [11,13].

The potential relevance of concomitant rotator-cuff tears remains

The nerve trajectory through the spinoglenoid notch is at an angle

◦

debated [10–12]. Less common causes include tumours, scapular

of about 60 [11].

fractures, and direct trauma involving traction.

The suprascapular nerve supplies the supraspinatus and

Early diagnosis and treatment are crucial to avoid the develop-

infraspinatus muscles. Its sensory territory, which varies widely,

ment of irreversible muscle wasting. Endoscopic surgery to treat

is located at the posterior and superior aspect of the shoulder over

the various causes of suprascapular nerve compression has super-

the glenohumeral joint space [14]. In addition, a posterior capsu-

seded open nerve release.

lar branch contributes to sensation from the glenohumeral joint,

Here, we will brieﬂy review the relevant anatomy then discuss

particularly its proprioception.

idiopathic suprascapular nerve entrapment and compression of the

Entrapment of the suprascapular nerve can occur at two sites,

nerve by cysts.

the suprascapular notch at the base of the coracoid process (of

which anatomic variants are both common and diverse) and

2. Anatomy of the suprascapular nerve

the spinoglenoid notch where the nerve runs beneath the infe-

rior transverse scapular ligament [15]. Aiello et al. distinguished

The suprascapular nerve is a mixed nerve that arises from the

involvement of one or both spinatus muscles depending on the site

brachial plexus, chieﬂy from the C5 and C6 roots (C5, 6%; C5 and

of entrapment relative to the bony scapular notches [16].

3. Diagnostic investigations

∗

Corresponding author. Service de chirurgie du membre supérieur, hôpitaux

Electrophysiological testing shows decreased conduction veloc-

universitaires, CCOM, 10, avenue Baumann, 67400 Illkirch, France.

E-mail address: [email protected] (P. Clavert). ities, increased distal motor conduction latency, and a neurogenic

http://dx.doi.org/10.1016/j.otsr.2014.10.002

S410 P. Clavert, H. Thomazeau / Orthopaedics & Traumatology: Surgery & Research 100S (2014) S409–S411

trace characteristic of neuropathy. Electrophysiological testing is

extremely useful in establishing both the diagnosis and the prog-

nosis. Nevertheless, its sensitivity is only 74% to 91% and the results

may be inconclusive in patients with muscle wasting.

Magnetic resonance imaging (MRI) not only visualises the initial

oedema related to muscle denervation and the muscle wast-

ing/fatty degeneration (speciﬁc cullet sign) [17]), but also detects

lesions potentially responsible for compression of the suprascapu-

lar nerve (chieﬂy para-labral cysts). MRI also identiﬁes the main

differential diagnoses (tumours and Parsonage-Turner syndrome).

4. Operative technique for nerve release at the

Fig. 1. Comparison of pre-operative and post-operative Constant scores.

suprascapular notch

As complements to the original description by L. Lafosse et al.

the largest improvements occurring for pain and strength. Distal

[18,19], other authors relied on anatomic studies [20–22]; Barwood

motor conduction latency improved after surgery in all 9 patients.

et al., 2007, #68 305; Plancher et al., 2007, #83 753} to develop

These outcomes are similar to those reported after open surgery.

either novel approaches or minimally invasive arthroscopic or

In a retrospective review of 42 patients managed with open nerve

endoscopic techniquesfor releasing the suprascapular nerve.

release between 1970 and 2002, Kim et al. [25] reported good recov-

The patient is usually in the semi-reclined position. A posterior

ery of supraspinatus function in 90% of patients, compared to only

optical portal and a superior lateral portal are created. The ﬁrst

32% for infraspinatus function. In contrast, the procedure was very

step is debridement of the subacromial bursa to the base of the

effective in providing pain relief. In 36 patients with suprascapular

coracoid process. The trapezoid and conoid ligaments are identiﬁed

nerve entrapment due to a variety of causes, Antoniou et al. [26]

anteriorly. The suprascapular notch is located at the attachment site

found a mean ASES shoulder score of 86 post-operatively com-

of these two coraco-clavicular ligaments and medial to the coracoid

pared to 53 pre-operatively. The severity of the electromyogram

process.

abnormalities did not correlate with the severity of the functional

The arthroscope is introduced through the lateral portal. A supe-

impairments. Similarly, after surgery, the degree of electromyo-

rior portal is created for the instruments (Neviaser approach), 5 cm

gram recovery failed to correlate signiﬁcantly with the degree of

from the lateral edge of the acromion. The debridementis continued

functional recovery.

cautiously to locate the artery coursing over the inferior transverse

scapular ligament, allowing identiﬁcation of the nerve and there-

6. Suprascapular nerve entrapment at the spinoglenoid

fore division of the ligament under the safest possible conditions. notch

Suprascapular nerve compression by a para-labral cyst is usually

5. Idiopathic suprascapular nerve entrapment

responsible for isolated involvement of the supraspinatus muscle.

Although para-labral cysts are generally located in the spinoglenoid

Idiopathic suprascapular nerve entrapment is difﬁcult to recog-

notch, they very often extend on either side of the scapular spine.

nise, and the low incidence of this condition often results in

A crucial step is evaluation for a labral lesion responsible for cyst

diagnostic delays. In situ, nerve release was long performed as an

development via a valve effect [7,8]. Labral lesions have been

open surgical procedure, with satisfactory results [23–26].

reported in 50% to 100% of cases, the most common being type

II SLAP tears. The risk of nerve injury may depend on the size of the

5.1. Our case-series cyst, being high if the cyst measures more than 30 mm along the

longest dimension. The advent of MRI resulted in the rediscovery

We retrospectively identiﬁed 9 patients who underwent surgery of para-labral cysts. MRI visualises the cyst, indicates the type of

over a 3-year period for isolated suprascapular nerve entrap- neurogenic nerve injury, and maps the resulting damage, which is

ment. There were 5 males and 4 females with a mean age of conﬁned to the infraspinatus muscle.

37.6 years (range, 21–66); among them, 7 were manual labour-

ers whose work involved use of the upper limbs. All 9 patients 6.1. Management

were right-handed and 7 had involvement of the right shoulder.

Mean symptom duration was 16 months (range, 7–60 months). Non-operative management has no role in the treatment of

All 9 patients underwent Constant score determination before and para-labral cysts. Similarly, cyst aspiration under ultrasound or

after surgery, pre-operative electrophysiological testing, and imag- computed-tomography guidance carries a 75% to 100% rate of fail-

ing studies that ruled out anatomic rotator-cuff abnormalities and ure or recurrence. Surgery is, therefore, mandatory. Arthroscopy

cysts putting pressure on the suprascapular nerve (Fig. 1). Surgical is the optimal method for treating not only the cyst, but also the

treatment consistently involved arthroscopic nerve release, with associated labral lesion. Standard portals are used to explore the

the patient in the semi-reclined position. The only procedure per- joint and to evaluate the extent of the lesions. The best course of

formed was division of the inferior transverse scapular ligament action in patients with both a cyst and a labral lesion is not agreed

as described by Lafosse et al. [18,19]. No immobilisation was used on. Isolated repair of the labrum has been described as sufﬁcient to

post-operatively. ensure healing and resolution of the cyst. However, combining cyst

Mean time to re-evaluation was 18 months (range, 6–30 evacuation and labral repair has been advocated. When no labral

months). A clinical evaluation and repeat electrophysiological lesion is found by imaging studies or during surgery, evacuation of

testing were performed. No intra-operative or post-operative com- the cyst can be achieved either by detaching the inferior aspect of

plications were recorded. Clinical improvements were documented the labrum then reattaching it at the end of the procedure or by

consistently. A single patient reported persistent muscle weakness. performing a juxta-labral incision in the joint capsule. A discharge

The Constant score was 54 before surgery and 81 after surgery, with of mucoid ﬂuid indicates evacuation of the cyst. Nerve release at the

P. Clavert, H. Thomazeau / Orthopaedics & Traumatology: Surgery & Research 100S (2014) S409–S411 S411

scapular notches remains controversial; in no case is this procedure References

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[31] Romeo AA, Ghodadra NS, Salata MJ, Provencher MT. Arthroscopic suprascapular

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P. Clavert is consultant for Mitek.

2010;19:118–23.

H. Thomazeau has no conﬂict of interest regarding this paper.