On this page· 3 sections
  1. 01Most Common Entrapments
  2. 02Diagnosis
  3. 03Treatment

Nerves around the shoulder (especially the suprascapular nerve and axillary nerve) can become compressed or injured due to ganglion cysts, capsular thickening, or trauma as they pass through narrow anatomical canals. This results in shoulder pain and weakness/atrophy of the shoulder muscles.

Most Common Entrapments

Suprascapular Nerve Entrapment

The suprascapular nerve passes through the notch above the shoulder blade (suprascapular notch) and supplies the supraspinatus and infraspinatus muscles, which are responsible for external rotation of the shoulder. In case of compression, deep pain in the posterior shoulder and significant atrophy of the shoulder muscles are observed.

Course of the suprascapular nerve around the shoulder joint and scapula

Axillary Nerve Injuries

The axillary nerve is frequently affected in shoulder dislocations and fractures of the humeral neck. It presents with weakness in lifting the arm sideways and numbness on the outer surface of the shoulder.

Ganglion Cysts

Ganglion cysts, formed by the accumulation of joint fluid leaking from labral tears around the capsule, are the most common mass lesions that can press on the suprascapular nerve.

Glenoid socket and labrum anatomy — ganglion cysts are associated with labral tears

Diagnosis

  • Physical examination: muscle atrophy, strength testing, and sensory evaluation
  • EMG: objective assessment of nerve conduction — the gold standard for diagnosis
  • MRI: imaging of ganglion cysts, labral tears, and muscle fatty degeneration

Treatment

In mild cases without cyst compression, rest and physical therapy are attempted. In the presence of a ganglion cyst or progressive muscle atrophy, arthroscopic cyst decompression + nerve release or open decompression is performed. Early release is crucial for the return of nerve function and halting muscle atrophy.

Arthroscopic view of a spinoglenoid cyst — arthroscopic cyst decompression relieves pressure on the nerve

Frequently Asked Questions

What are the symptoms of nerve entrapment in the shoulder?
Dull and constant pain in the back of the shoulder, atrophy of the shoulder muscles, and weakness in lifting the arm sideways and upwards are typical symptoms.
How is nerve entrapment diagnosed?
Muscle atrophy and weakness are detected during physical examination; EMG (electromyography) confirms nerve damage, and MRI shows compressing structures like ganglion cysts.
What is a ganglion cyst?
It is a benign sac filled with gel that originates from the joint capsule. It can cause nerve entrapment by compressing the suprascapular nerve canal; it is often associated with a labral tear.
Does nerve entrapment heal without surgery?
In mild cases, rest and physical therapy may be sufficient. Surgical decompression is considered in the presence of cyst compression or progressive muscle atrophy.