Severe brachial plexopathy after an ultrasound-guided single-injection nerve block for total shoulder arthroplasty in a patient with multiple sclerosis: what is the likely cause of this complication?

To the Editor:—We read with interest the case report published by Koff et al. and the editorial by Hebl. How can Dr. Hebl discuss the role that the use of an ultrasound may have played in this case? Ultrasound allows us to visualize the nerves and the spread of local anesthetic. From the authors’ description, it is clear that except for the use of 0.5% bupivacaine, the technique used to perform the interscalene block could not have led to such a catastrophic outcome. The injection of local anesthetic was not intraneural, because the authors reported that “the local anesthetic was noted to surround C5–C6” and that intraneural injections have been demonstrated to produce swelling of the nerve. In addition, how would a 22-gauge blunt needle, even in the hands of a resident under the supervision of an attending, be able to damage the three trunks? What was really surprising about the case report and the editorial is that none of the authors questioned the use of 30 ml bupivacaine, 0.5%. Bupivacaine neurotoxicity is well established. Because general anesthesia was the main anesthetic technique, why did the author choose to perform an anesthetic (0.5% bupivacaine) and not an analgesic block (0.25% bupivacaine)? More importantly, why was bupivacaine chosen rather than a less toxic drug such as ropivacaine? In the presence of a theoretical increase in the possibility of nerve injury, would it be logical to choose the local anesthetic and the concentration with the least potential for neurotoxicity? There is no doubt that considerations should be given to the role played by multiple sclerosis (MS) in the postsurgical complication. Before arguments can be presented to contraindicate the use of peripheral nerve block in the patient with MS, could we at least also consider the possibility that MS might increase the surgical risk of a nerve injury, especially when considering that shoulder surgery is associated with a risk of permanent nerve injury much more frequently than peripheral nerve block? In conclusion, from the data presented, it is impossible to determine whether the complication presented was directly related to the surgery or was the result of an MS-related increase in the surgical risk or an MS-related increase in the local anesthetic toxicity. What is certain is that the use of ultrasound had nothing to do with the outcome.