The geyser sign is the flow of arthrographic contrast or joint fluid from the glenohumeral joint across the acromioclavicular joint (ACJ) to form a supraclavicular collection. It is seen in some cases of long-standing rotator cuff tear and advanced degenerative change of the shoulder.
It may present as a pseudotumor above the ACJ which is classically described as slow-growing.
Chronic rotator cuff degenerative change and full-thickness tearing leads to instability of the humerus in the glenohumeral joint. Eventually, chronic impaction from the humeral head disrupts the inferior ACJ capsule, and glenohumeral joint fluid "erupts" superiorly through the acromioclavicular interval from the subacromial subdeltoid bursa and glenohumeral joint.
There is often a high riding humeral head abutting the acromion or ACJ indicating rotator cuff tears. There may be signs also of rotator cuff arthropathy.
- after injection of arthrogram solution into the glenohumeral joint, the solution will decompress and extend into the subacromial subdeltoid bursa (through the cuff tear) and into the ACJ
- background advanced degenerative changes in the shoulder with a full-thickness rotator cuff tear, as with a bare humeral head sign
- hypoechoic fluid collection above the AC joint
- ensure that the collection is genuinely fluid and not an exuberant hypoechoic degenerative change of the AC joint or mass with color Doppler
- background advanced degenerative change in the shoulder with a full-thickness rotator cuff tear
- T2: hyperintense fluid tracks from the glenohumeral joint space into the subdeltoid bursa and into ACJ
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