Presentation
Left brachial plexus birth palsy.
Patient Data
The MRI sequences demonstrate a severe deformity of the humeral head and glenoid cavity. Flattened glenoid cavity with dysplastic, flattened and posteriorly displaced humeral head.
In this case, the gleno-scapular angle measured at the posteromedial quadrant (using the method described by Friedman et al 1) was at 75°. The glenoid version is 75°-90° = -15° (a negative value of this angle indicates a glenoid retroversion).
More than 2/3 of the humeral head appears posterior to the scapular line indicating a posterior luxation.
Case Discussion
MRI features of a glenohumeral dysplasia with posterior dislocation of the humeral head scondary to brachial plexus palsy.
The main described bone deformities secondary to brachial plexus birth palsy include 1:
- glenoid retroversion: usually progressive
- flattening or absence of the glenoid cavity
- thinning with loss of the posterior glenoid margin
- dysplasia of the humeral head with posterior subluxation or luxation
- others bone anomalies may be seen:
- shortening of the clavicle.
- hypoplasia of the scapula
- inferior deviation of the acromion