We studied 165 cases of thoracic-outlet syndrome in 142 patients in whom
resection of the first rib had been performed. In seventy-three cases (44
per cent), there was compression of a nerve distally, as shown by
electromyography and conduction studies. The most common secondary
compression was carpal tunnel syndrome (forty-one cases). Thirteen patients
needed an operation at three sites or more. Our results show that proximal
compression of a nerve lessens its ability to withstand more distal
compression. Once the diagnosis of thoracic-outlet syndrome has been made,
the possibility of an additional distal compression neuropathy should be
investigated.