Cervical root stimulation in a case of classic neurogenic thoracic outlet syndrome.

We performed C8 nerve root stimulation in addition to other electromyographic (EMG) studies in a surgically proven case of classic thoracic outlet syndrome (TOS). The patient was a 19-year-old woman with a 2-year history of right hand cramps and progressive weakness and atrophy of hand muscles, especially the thenar eminence. Routine EMG studies showed evidence for an axon-loss lower trunk brachial plexopathy. Stimulation studies of the C8 nerve roots demonstrated proximal conduction block on the affected side only. The diagnosis was further supported by cervical spine radiographs, which demonstrated a cervical rib, and surgical exploration of the brachial plexus, which demonstrated upward compression and stretching of the lower trunk by a fascial band extending from the anomalous cervical rib to the first thoracic rib. The patient noted a modest improvement in hand function postoperatively. Root stimulation studies can help in the diagnosis of classic TOS by providing more precise localization and information regarding the degree, if any, of proximal motor conduction block.