(Neuralgic amyotrophy, Acute brachial plexus neuropathy)
Rare neurological disorder manifesting as sudden onset of severe pain in the shoulder and scapular areas. When in the left shoulder area, the patient starts worrying about heart attack and goes to the ER. It may also be mistaken for acute capsulitis of the shoulder and the orthopedic surgeon may give corticosteroid injection in the shoulder. Within a few days muscle weakness sets in. Most often muscles around the shoulder are affected, but sometimes muscles supplied by a distal nerve may become weak; this may result in difficulty with use of the hand.
The exact cause of neuralgic amyotrophy is unknown. Most scientists believe that it is an autoimmune reaction to a viral infection. Sometimes it occurs following vaccination or a surgical procedure.
The diagnosis is based on the clinical picture. Nerve conduction and EMG studies are useful in determining which nerves affected and how severely.
Most patients experience significant improvement in the pain and weakness within months. No specific treatment is available; pain relievers and physical therapy are helpful.