Complications of Interscalene Brachial Plexus Block Tracked in 9-Month Prospective Study. Borgeat et al. (page 875)

To further investigate the acute and chronic effects associated with interscalene brachial plexus blocks (ISB), Borgeat et al.  evaluated 521 patients after they underwent elective shoulder procedures. One patient sustained iatrogenic nerve damage related to his surgery and so was excluded from the study. Of the remaining 520 patients who completed the study, 234 had an ISB with placement of a catheter, whereas 286 received an ISB with the single-injection technique. All acute perioperative complications were recorded, and patients were observed daily for 10 days for paresthesia, dysesthesias, pain not related to surgery, and muscle weakness. There were two episodes of acute complications: one pneumothorax and one incidence of central nervous system toxicity (incoherent speech). On the 10th day after surgery, 74 patients (14%) reported paresthesia, dysesthesia, or pain apparently not related to surgery. For all of these patients, symptoms were mild, and none had accompanying muscle weakness.

At 1 month after surgery, 41 patients (7.9%) reported persistent symptoms. Thirty of these patients underwent electroneuromyography, and eight cases of sulcus ulnaris syndrome, two cases of carpal tunnel syndrome, and one case of complex regional pain syndrome were diagnosed. Of the patients who had a diagnosis of sulcus ulnaris syndrome, six recovered spontaneously between 1 and 3 months, and the remaining two were treated with surgical decompression of the ulnar nerve. Two patients with carpal tunnel syndrome at 1 month and two with carpal tunnel syndrome at 2 and 3 months after surgery were treated surgically and recovered. By 9 months after surgery, only one patient, who had a plexus lesion, was still symptomatic. Despite the high incidence of transient paresthesias, dysesthesias, and pain not related to surgery, ISB has a high success rate. It is important to detect sulcus ulnaris syndrome, carpal tunnel syndrome, and complex regional pain syndrome to treat these problems. As shown in this study, the remainder of the patients did not have chronic ISB-related problems.