Neuralgic Amyotrophy: A Commonly Overlooked Cause of Acute Shoulder Pain.

Background: Neuralgic amyotrophy (NA) is a multifactorial, monophasic neuritis that mainly affects the nerves of the shoulder girdle. It is characterized by very severe pain and by weakness that arises some time after the pain. Its reported incidence is high (100 cases per 100 000 persons per year), but our data suggest that many or most cases are diagnosed late or not at all. Methods: This review of the epidemiology, pathophysiology, diagnosis, and treatment of NA is based on pertinent publications retrieved by a selective literature search, and on data provided by the scientific institute of AOK, a German statutory health-insurance carrier. Results: It is currently thought that the combination of a genetic predisposition, an immunological trigger factor, and mechanical stress on the affected nerve segment(s) is pathophysiologically determinative. The prognosis of untreated NA is poor, with 25% of patients remaining unable to work at three years. The main form of treatment is with corticosteroids that are administered as early as possible. If there is evidence of nerve constriction or torsion, surgery may also help. There have only been six controlled cohort studies on the treatment of NA, and no randomized trials. It is not uncommon for the acute phase to develop into a chronic pain syndrome requiring multidimensional treatment. Conclusion: Particularly in view of the high incidence and improved therapeutic options, NA should be included in the differential diagnosis of all patients with suggestive symptoms. [ABSTRACT FROM AUTHOR]