What is quadrilateral space syndrome?

Quadrilateral space syndrome is a rare nerve condition in the shoulder, causing pain and/or weakness in the back of the shoulder. It involves compression of the axillary nerve at the back of the shoulder, usually by a band of ligament-like (fibrous) tissue or between the teres major and teres minor muscles in the back of the shoulder. The axillary nerve supplies the deltoid muscle, the main muscle to the shoulder.

The quadrilateral space is a space in the back of the shoulder formed by three muscles, the teres minor muscle above, the teres major below, and the triceps muscle on one side, with the arm bone (humerus) on the remaining side. The axillary nerve and posterior circumflex humeral artery run through this space. This space can be closed down, compressing the nerve and artery when the arm is in the throwing position, as well as by fibrous bands.

How our shoulder experts can help

Our shoulder experts will diagnose and treat your condition using the latest advances in orthopaedic technology. To request an appointment with our physicians, please call 202-833-1147.

What causes quadrilateral space syndrome?

Quadrilateral space syndrome is caused by pressure on the axillary nerve at the back of the shoulder, often by a fibrous band or compression between the teres minor and teres major muscles.

What increases the risk?

• Contact sports
• Sports that require throwing (baseball pitchers)
• Poor physical conditioning (strength and flexibility)

What are the symptoms of quadrilateral space syndrome?

• Pain and discomfort (burning or dull ache) that is poorly localized (not confined to one spot), often in the back of the shoulder, and occasionally the front of the shoulder and arm
• Heaviness or fatigue of the arm
• Pain made worse by putting the arm in the thrower’s position
• Tingling, numbness or burning in the back of the shoulder or, occasionally, the arm and forearm
• Tenderness in the back of the shoulder
• Atrophy (shrinkage) of the deltoid muscle or teres minor muscle

How is quadrilateral space syndrome diagnosed?

History and physical exam are usually suggestive of this diagnosis, although its infrequency makes it a diagnosis of exclusion. Because it presents with shoulder pain similar to many other conditions, it is low on the list of diagnostic alternatives. In the patient with persistent activity-related pain, particularly a throwing athlete, further diagnostic imaging studies to evaluate for compromise of the vascular flow to this area is warranted.

Are there any special tests?

An arteriogram is the definitive test of choice in diagnosing this condition. During this test, a small catheter is advanced and contrast dye is injected. Fluoroscopy (live X-ray) is the used to observe the dye’s distribution. Decreased flow, narrow vessel or kinking of the axillary artery confirms the diagnosis.

How is quadrilateral space syndrome treated?

Non-operative treatment: Initial treatment consists of rest from the offending activity and medications to help reduce inflammation and pain. Stretching exercises of the shoulder muscles are useful. Referral to a physical therapist or an athletic trainer may be recommended for further treatment, including ultrasound and other modalities. Injections with cortisone, often with numbing medicine, to the area where the nerve is being pinched may be recommended to help reduce the nerve inflammation and pinching.

Operative (or Surgical) treatment: If conservative treatment is not successful, surgery may be necessary to free the pinched nerve by cutting the fibrous band where the nerve is being pinched. When surgery is necessary, it provides almost complete relief in most patients who undergo this operation.

What are the complications from treatment?

Possible complications of non-operative treatment include:

• Persistent pain and activity impairment, inability to continue to throw

Possible complications of operative treatment include:

• Surgical complications not specifically associated with the shoulder, such as pain, bleeding (uncommon), infection (<1percent), nerve injury (uncommon), stiffness, problems with anesthesia, and inability to return to previous level of pre-injury activity.
• Complications specific to surgical treatment of this condition: Persistent pain, injury to the axillary artery or nerve (rare). The patient may fail to improve if this diagnosis is inaccurate.

How can quadrilateral space syndrome be prevented?

• Appropriately warm up and stretch before practice or competition
• Maintain appropriate conditioning:
  • Shoulder flexibility
• Muscle strength and endurance