Chronic glenohumeral dysplasia secondary to brachial plexus birth palsy

Fifteen-year-old male with upper right limb dysfunction since birth, from vaginal delivery. He had deficit on active external rotation but preserved mobility.

On radiographs/MR, flattening and retroversion of the right glenoid (loss of its posterior margin) were demonstrated due to internal rotation contracture. This measured -35º (normal range of 4.7º to -8.1º) [1]. This alters glenohumeral mechanics, leading to static posterior subluxation, and the percentage of the humeral head anterior to the scapular line is around 10% [2]. Flattening of the humeral head, acromion downsloping, and coracoid elongation with anterior projection are also present.

The rotator cuff trophism is preserved, and a low-grade articular capsular distension can be also detected with the formation of a pseudocyst anteriorly.

Background

Brachial plexus birth palsy is an upper extremity paralysis which occurs after traction injury of the nerves during the delivery. Most patients will recover from the deficits, especially by recruiting scapulothoracic motion, but 10–30% will have residual neurologic damage, resulting in alteration in upper limb development and function [3]. Incomplete neurologic recovery leads to muscle imbalance, internal rotation contracture, and glenohumeral dysplasia (GHD) [4]. The latter comprises glenoid and humeral head articular incompatibilities, deformity of the glenoid and subluxation or dislocation of the glenohumeral joint [5].

Clinical perspective

MR examination is useful to assess the brachial plexus and the shoulder. GHD can manifest as early as 3 months and is typically described at a young age [6,7]. We presented a rare case of a teenager with untreated disease.

Imaging perspective

Brachial plexus birth palsy should be assessed by MR, where both the nerve route and the glenohumeral articulation are visible.

On MR, glenohumeral dysplasia is manifested as poor humeral head coverage, resulting in its abnormal translation and posterior static subluxation.

Measurements of the glenoid version (angle formed by the line drawn at the anterior and posterior aspects of the glenoid margins and the line between the medial borders of the scapula and the midpoint of the glenoid borders is measured, then 90º are subtracted, in our case, is -35º) and the degree of posterior subluxation of the humeral head should be obtained to define the treatment in infancy and to evaluate the evolution.

The translation of the humeral head is defined as the percentage of the bone anterior to the scapular line. Posterior subluxation is defined when the measurement of the humeral head coverage is between 0% and 35%; our case had 10% and was classified as type 3 or C deformity according to Walter and Walch’s systems, respectively [8,9].

Outcome

Physiotherapy, with or without surgery, is the cornerstone of treatment in infancy. Patients older than 4 years should also be assessed for the ability to reach the mouth and the back of the head, as an operation may be indicated. Shoulder function was compatible with our patient’s regular activities; therefore, physiotherapy was continued.

Take home message

The radiologist should be familiar with the assessment and the correct measurements of the glenohumeral dysplasia in children since, in combination with the physical exam, it has a clinical impact on the outcome.

Written informed patient consent for publication has been obtained.