A retrospective analysis of neurological complications after ultrasound guided interscalene block for arthroscopic shoulder surgery

ABSTRACT

BACKGROUND: Ultrasound-guided interscalene brachial plexus block (US-ISB) has been reported to be effective postoperative analgesia for arthroscopic shoulder surgery. Although considered rare, various neurological complications have been reported. We retrospectively evaluated 668 patients for post operation neurological symptoms including hemidiaphragmatic paresis and post-operative neurologic symptoms after US-ISB. METHODS: We performed a retrospective chart review of 668 patients undergoing shoulder surgery with single-shot US-ISB from January 2010 to May 2015. The general anesthesia prior to the US-guided ISB procedure was standardized by expert anesthesiologists. Neurological postoperative complications were evaluated at 48 hours, about 2 weeks, 1 month, 3 months, 6 months, and up to resolution after operation. RESULTS: Three patients (0.4%) developed hemidiaphragmatic paresis (HDP), which were likely US-ISB associated and improved within 1 day. Two patients developed sensory symptoms, also likely US-ISB associated; one was paresthesia at the tip of the thumb/index finger, which resolved within 2 weeks, and the other was hypoesthesia involving the posterior auricular nerve, which resolved within 6 months. Motor and sensory symptoms which were not likely associated with US-ISB were hypoesthesia and pain (n = 28, 4.6%) and motor weakness (n = 2, 0.3%). CONCLUSIONS: Incidence of HDP and neurological complications, respectively 0.4% and 0.3%, related to transient minor sensory symptoms occurred after US-ISB for arthroscopic shoulder surgery but the complications improved spontaneously. Therefore, we confirm that the US-ISB procedure with low volumes of local anesthetics is an acceptable technique with a low rate of HDP and neurological complications.