Acute and nonacute complications associated with interscalene block and shoulder surgery - A prospective study

Background: The incidence, etiology, and evolution of complications after i nterscalene brachial plexus block (ISB) are not well-known. The authors pro spectively monitored 521 patients for complications during the first 9 mont hs after ISB. Methods: A total of 521 adults scheduled for elective shoulder surgery perf ormed with art ISB were included in this prospective study. The ISB procedu re was standardized for all patients. Acute complications were recorded. Pa tients were observed daily (for 10 days) for paresthesias, dysesthesias, pa in not related to surgery, and muscular weakness and were evaluated at 1, 3 , 6, and 9 months after surgery. Persistence of paresthesias, dysesthesias, pain not related to surgery, or muscular weakness was investigated at 1 or 3 months by means of electroneuromyography. Final evaluation was performed at 9 months. Results: A total of 520 patients completed the study; one was excluded afte r surgical axillary nerve damage. Two hundred thirty-four patients had an i nterscalene catheter. Acute complications consisted of one pneumothorax (0. 2%) and one episode of central nervous system toxicity (incoherent speech; 0.2%). At 10 days, 74 patients (14%) were symptomatic, and none had muscula r weakness. At 1 month, 41 patients (7.9%) had symptoms, and none bad muscu lar weakness. Thirty patients underwent electroneuromyography; sulcus ulnar is syndrome (n = 8), carpal tunnel syndrome (n = 2), and complex regional p ain syndrome (n = 1) were diagnosed. At 3 months 20 patients (3.9%) were sy mptomatic, and none had muscular weakness. All underwent electroncuromyogra phy; carpal tunnel syndrome (n = 2), complex region at pain syndrome (n = 4 ), plexus neuropathy (n = 1), and plexus damage (n = 1) were diagnosed. At 6 months, 5 patients (0.9%) were symptomatic. At 9 months, 1 patient (0.2%) had persistence of dysesthesia. Conclusions: Interscalene brachial plexus block performed with a standardiz ed technical approach, material, and drugs is associated with an incidence of short- and severe long-term complications of 0.4%. In case of persistent paresthesia, dysesthesia, or pain not related to surgery after ISB, sulcus ulnaris syndrome, carpal tunnel syndrome, or complex regional pain syndrom e should be excluded since specific treatment may be required.