Background Nerve compression of the brachial plexus can be provoked by the Abduction External Rotation (AER) test where the arms are held in a ''hands-up'' position. Methods The AER test was conducted among 137 male industrial and offıce workers at baseline and after 5 years follow-up, together with a medical examination/history and exposure analysis. Nerve conduction measurements in the wrist regions were also made.
Results
The cumulated incidence of neurological signs during the AER test, was estimated to be 2/100 person-years. Factors related to work-conditions, constitution, disease, and neck trauma were associated with AER signs. Subjects with AER signs exhibited a slowing of the nerve conduction velocities in the wrist region. The AER test predicted future neck and upper extremity symptoms and signs of nerve compression. Conclusions The results of this study gave support to the ''double or multiple crush'' theory of nerve compression. Prevention, evaluation, and management of neck and upper extremity nerve compression diseases should, therefore, attend to all probable locations of such compression, even when a specific location is in focus. The AER test can be a supplementary tool in such work, both in epidemiological and occupational health settings.