Transient hemidiaphragmatic paresis after ultrasound-guided lateral sagittal infraclavicular block.

As compared with medial approaches for the infraclavicular brachial plexus block, lateral approaches generally have no impact on the phrenic nerve or pulmonary function. A patient experienced transient hemidiaphragmatic paresis after ultrasound-guided lateral sagittal infraclavicular block for lower arm surgery. An accessory phrenic nerve, ie, an anatomical variation, may have been the mechanism of transient hemidiaphragmatic paresis in this patient.