Denervation syndromes of the shoulder girdle: MR imaging with electrophysiologic correlation.
OBJECTIVE
To investigate the use of MR imaging in the characterization of denervated muscle of the shoulder correlated with electrophysiologic studies.


METHODS
We studied with MR imaging five patients who presented with shoulder weakness and pain and who underwent electrophysiologic studies. On MR imaging the distribution of muscle edema and fatty infiltration was recorded, as was the presence of masses impinging on a regional nerve.


RESULTS
Acute/subacute denervation was best seen on T2-weighted fast spin-echo images with fat saturation, showing increased SI related to neurogenic edema. Chronic denervation was best seen on T1-weighted spin-echo images, demonstrating loss of muscle bulk and diffuse areas of increased signal intensity within the muscle. Three patients showed MR imaging and electrophysiologic findings of Parsonage Turner syndrome. One patient demonstrated an arteriovenous malformation within the spinoglenoid notch, impinging on the suprascapular nerve with associated atrophy of the infraspinatus muscle. The fifth patient demonstrated fatty atrophy of the teres minor muscle caused by compression by a cyst of the axillary nerve and electrophysiologic findings of an incomplete axillary nerve block.


CONCLUSIONS
MR imaging is useful in detecting and characterizing denervation atrophy and neurogenic edema in shoulder muscles. MR imaging can provide additional information to electrophysiologic studies by estimating the age (acute/chronic) and identifying morphologic causes for shoulder pain and atrophy.
Bredella
M A
MA
Department of Radiology, University of California San Francisco, 505 Parnassus Avenue, Suite M-392, San Francisco, CA 94143-0628, USA.
Tirman
P F
PF
Fritz
R C
RC
Wischer
T K
TK
Stork
A
A
Genant
H K
HK
D000328:Adult; D020968:Brachial Plexus Neuritis / Q000150:complications / Q000175:diagnosis; D020516:Brachial Plexus Neuropathies / Q000150:complications / Q000175:diagnosis*; D004576:Electromyography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009133:Muscular Atrophy / Q000175:diagnosis / Q000209:etiology; D009431:Neural Conduction; D012782:Shoulder / Q000473:pathology*; D019534:Shoulder Impingement Syndrome / Q000150:complications / Q000175:diagnosis*