Presentation
Sudden onset severe shoulder pain and weakness.
Patient Data
Sagittal, coronal, and axial fat-saturated MR images show edema of the supraspinatus, infraspinatus, and teres minor muscles. The deltoid muscle is spared.
This case also shows findings of supraspinatus tendinopathy, a downsloping acromion, and mild subacromion/subdeltoid bursitis.
Case Discussion
Rotator cuff denervation syndromes may be due to by a variety of causes, most important are:
- viral or autoimmune neuritis: Parsonage-Turner syndrome
- fibrous bands
- paralabral cyst
- traumatic nerve injury (stretching/traction injury)
Typical muscular innervations are:
-
suprascapular nerve
- supraspinatus muscle
- infraspinatus muscle
-
axillary nerve
- teres minor muscle (5th cervical nerve)
- deltoid muscle (5th & 6th cervical nerves)
-
upper and lower subscapular nerve
- subscapularis muscle
- teres major
In this case, the distribution of affected muscles doesn't follow a single myotomic innervation, consistent with a polyneuropathy such as Parsonage-Turner syndrome.
Please note that the chronic stage differs in MRI appearance.