Incidence of unintentional intraneural injection and postoperative neurological complications with ultrasound-guided interscalene and supraclavicular nerve blocks

It is proposed that ultrasound guidance decreases the risk of intraneural injection and associated postoperative neurological complications. However, the incidence of unintentional intraneural injection with ultrasound is unknown. Two hundred and fifty-seven patients were enrolled in a prospective, single-blind observational study. All patients underwent a pre-operative neurological examination before ambulatory shoulder arthroscopy with sedation and ultrasound-guided interscalene or supraclavicular block. Patients were followed up at 1 week and at 4-6 weeks postoperatively. Two blinded anaesthesiologists viewed the same video of the ultrasound image during the block offline to determine intraneural trespass. Intraneural injection occurred in 42 patients (17%; 95% CI 12-22%). No patient suffered from postoperative neurological complications (0%; 95% CI 0-1.6%) at follow-up.