Evaluation of the lateral modified approach for continuous interscalene block after shoulder surgery

Background Continuous interscalene block is the technique of choice for postoperative pain relief treatment after shoulder surgery. The authors prospectively evaluated the modified lateral approach for the performance of the interscalene catheter block and monitored 700 patients for clinical efficacy and complications during the first 6 months after placement of the catheter. Methods: A total of 700 adults scheduled to undergo elective shoulder surgery performed with an interscalene brachial plexus block through an interscalene catheter were included in this study. The interscalene brachial plexus block procedure was standardized for all patients. Difficulties in placement of the catheter, clinical efficacy of anesthesia and analgesia, patient satisfaction, and acute and chronic complications were recorded. Patients were observed daily for 5 days for any complications and were evaluated at 1, 3, and 6 months after surgery. Persistence of neurologic complication was investigated by electroneuromyography. Results: A total of 700 adults completed the study. Easy placement of the catheter (one attempt) was achieved in 86% of the patients. Resistance to thread the catheter was encountered in 6%; no major complications were observed during injection of the initial bolus. The success rate for anesthesia was 97%. Postoperative analgesia was efficient in 99%. The concentration and the rate of infusion of ropivacaine had to be increased in 31 patients (6%). In five patients (0.7%), signs of local infection around the puncture point were noted; in one patient (0.10/6), a collection of pus was surgically drained. Patient satisfaction was 9.6 on a scale of 0-10. Minor neurologic complications (paresthesias, dysesthesias, pain not related to surgery) were observed in 2.4%, 0.3%, and 0% at 1, 3, and 6 months, respectively. At 1 month, three sulcus ulnaris syndromes, one carpal tunnel syndrome, and one complex regional pain syndrome were diagnosed. Two patients (0.2%) had sensory-motor deficit, which necessitated 19 and 28 weeks to recover. Electromyography was suggestive of partial axonotmesis. Conclusion: The lateral modified approach provides good conditions for placement of the interscalene catheter. Anesthesia and analgesia performed through the catheter are efficient. The rates of infection and neurologic complications are low, and patient satisfaction is high.