Brachial plexus injury after shoulder surgery with continuous interscalene block is 2.4% at 1 month and 0% at 6 months, but may be higher with a systematic postoperative neurological examination. Indeed, femoral neuropathy after anterior cruciate ligament reconstruction is 24% at 6 weeks in a cohort of 20 consecutive patients systematically screened with an electromyogram. Brachial plexus injury may be the consequence of the surgery (direct lesion by traction) or the continuous interscalene block. The goal of this study is to define the etiology of this postoperative neuropathy.