Delayed Onset and Prolonged Horner Syndrome in Two Children After Single-Shot UltrasoundGuided Infraclavicular and Subclavian Perivascular Brachial Plexus Blocks for Upper Extremity Surgery: Case Reports.

Horner syndrome is a known complication of cervical approaches to brachial plexus blocks due to local anesthetic-induced oculosympathetic paresis. It has rarely been described in relation to ultrasound-guided brachial plexus blocks in children. This syndrome is usually self-limiting but may cause apprehension to the child, parents, and the treating physicians until its resolution. We report delayed manifestations of Horner syndrome in 2 children following ultrasound-guided infraclavicular and subclavian perivascular blocks.