Convulsions Induced by Ropivacaine During Interscalene Brachial Plexus Block

Abstract

In Response: Borgeat and Ruetsch are no doubt correct in their claim that the IV injection of 15 mg of ropivacaine is unlikely to cause convulsions. In our case, we believe that the injection was directly into the vertebral artery. This is a well recognized complication of interscalene brachial plexus block. In such instances, a bolus of local anaesthetic is delivered directly to the brain with minimal dilution by blood, and even a small dose is likely to exceed the seizure threshold. Thus, we believe a 2-mL test dose to be of some practical use in relation to this particular regional technique. Moreover, the addition of epinephrine is unlikely to elicit more information with a direct injection into the vertebral artery. However, we agree with the authors that, in general, small test doses of ropivacaine are unlikely to produce convulsions and that the addition of a sympathomimetic drug such as epinephrine may provide valuable information when injected directly into a vein. In the case we reported, blood was not drawn for measurement of ropivacaine levels. In relation to the technique used in the block, this was performed as outlined in Cousins and Bridenbaugh [1]. We endorse the statement by Borgeat and Ruetsch that technical principles must be respected if serious complications are to be avoided. Ben Korman Richard H. Riley Department of Anesthesia; Royal Perth Hospital; Perth, WA 6001, Australia