Conventional electromyographic and nerve-conduction studies usually do
not show abnormalities in patients who have a clinical diagnosis of radial
tunnel syndrome. Therefore, posterior interosseous nerve-conduction
measurements were performed during forced supination in patients who had
this syndrome. Only one of sixteen patients had a major increase in
latency. Our data do not support the hypothesis that the signs and symptoms
in most patients who have a diagnosis of radial tunnel syndrome are caused
by compression of the posterior interosseous nerve.