［Objective］Brachial plexus injury（BPI）associated with thoracic surgery is a rare complication. We report the clinical features of this condition, and investigated the cause and pathophysiology.
［Methods］Sixteen patients（mean age 67.0）with BPI following thoracic surgery were included in this study. Median sternotomy was performed for all patients. We investigated the type of palsy, clinical symptoms, factors leading to this condition, treatment, and prognosis.
［Results and conclusions］The type of palsy was lower type for all patients. Weakness of wrist extension and finger flexion in 12 patients, and slight motor disturbance in 4 patients developed after the operation. Hypesthesia at the level of C7/8 in all patients and burning sensation in 3 patients developed postoperatively. Thirteen patients had ipsilateral first rib fracture. All patients were treated conservatively. Motor disturbance recovered to MMT 5 in 10 patients and to MMT 4 in 5 patients within 6 months postoperatively. BPI was detected in 15 of 848 patients（1.8%）who underwent thoracic surgery with median sternotomy. We hypothesized that the lower brachial plexus was compressed between the first rib and clavicle due to excessive sternal retraction because ipsilateral first rib fracture was present in 13 of 16 patients（81.3%）.
