Working Diagnosis:
Parsonage-Turner syndrome

Treatment:
-Patient was started on Neurontin and Prednisone for likely Parsonage-Turner syndrome based on EMG findings.
-She was referred to Neurology for further recommendations regarding treatment and prognosis.
-We discussed that a glenohumeral injection could be considered in the future for possible underlying adhesive capsulitis if her pain is not completely improved with treatment measures geared toward diagnosis of Parsonage-Turner.

Outcome:
Three months after her initial visit, patient reports only mild improvement in her symptoms despite PT and conservative measures. She is awaiting a consult by Neurology at this time.

Editor's Comments:
Parsonage-Turner Syndrome is also referred to as idiopathic brachial plexopathy, or neuralgic amyotrophy. It is a rare disorder characterized by the abrupt onset of shoulder pain, usually unilateral, followed by progressive neurologic deficits including motor weakness, dysesthesias, and numbness. The exact cause of this syndrome is unknown, but is has been reported in various clinical situations, including postoperatively, postinfectious, posttraumatic, and postvaccination situations. Risk factors include a recent viral illness, reported in 25% of patients, or a recent immunization, reported in 15% of cases. Some theorize that PTS is caused by a viral illness that directly involves the brachial plexus, or may be due to an autoimmune response to the virus or the to the viral antigen in an immunization. Others believe that there may be a vascular or ischemic etiology.It is often a diagnosis of exclusion.
In this case, EMG testing was critical to the diagnosis.
Because PTS is believed to be an axonal process, widespread denervation is usually seen in involved muscles, and complete denervation is often the case. It can take 6-12 months to see reinnervation.
Initial treatment focuses on pain management as mentioned in the case. Oral steroids have been recommended by some to shorten the duration of symptoms, but there is little evidence to support its effectiveness. Physical therapy can help with with restoring the range of motion and strength of the affected muscles. Most patients have a favorable, functional recovery, albeit over many months of rehabilitation.

References:
Feinberg, JH, Radecki, J. Parsonage-Turner Syndrome.HSS J. 2010 Sep; 6(2):199-205. ncbi.nlm.nih.gov

Acknowledgments:
Jeffrey R. Brown, MD - case editor

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