Brachial plexus blockade arising from a combined pectoralis (PECS) 1 and 2 block

Summary We present a case of inadvertent spread of local anaesthetic from combined pectoralis (PECS) 1 and 2 fascial plane blocks that resulted in an incomplete brachial plexus block. An otherwise healthy 42‐year‐old woman with a body mass index of 23.3 kg.m−2 presented for unilateral mastectomy with immediate prosthetic reconstruction for breast cancer. No axillary dissection was performed. Because of service requirements, the blocks were performed at the conclusion of surgery. This may have resulted in greater cranial spread of the local anaesthetic due to surgical dissection along musculature and placement of the breast implant. Following emergence from general anaesthesia, the patient experienced numbness over the ipsilateral medial forearm extending to the little finger. Further examination with a finger‐nose test revealed reduced coordination and joint proprioception of the ipsilateral arm. There was no detectable gross motor weakness. She was reviewed the following day (23 h after the blocks) by which time her symptoms had subsided entirely. We believe that this is the first documented brachial plexus block after injection of local anaesthetic into the pectoralis 1 and 2 fascial planes.