Shouldering the evidence burden: conflicting testimony in a case of interscalene block

Interscalene block for postoperative analgesia using only ultrasound guidance: the outcome in 200 patients

“…In addition, this approach avoids needle contact with the phrenic nerve as it passes over the AS muscle and into the interscalene groove at the level of the sixth cervical vertebra. Although they are rare, cases of permanent phrenic nerve injury after the classic approach to the ISB have been reported [10,11].…”