Cappelleri G, et al. - In this study involving forty-seven consecutive American Society of Anesthesiologists physical status I-II patients, researchers determined the minimum effective volume of intraneural ropivacaine 1% for complete sensory-motor sciatic nerve block in 90% of patients, and related electrophysiologic variations. Study participants were patients who received an ultrasound-guided popliteal intraneural nerve block following the up-and-down biased coin design. Findings revealed that the minimum effective volume of ropivacaine 1% in 90% of patients for complete sensory-motor sciatic nerve block resulted in 6.6 ml with an onset time of 19 ± 12 min and 98% success rate. Overall, an effective sensory-motor block was achieved with a significantly reduced local anesthetic dose due to the use of intraneural ultrasound-guided popliteal local anesthetic injection. Moreover, this strategy decreased the risk of systemic toxicity. Persistent electrophysiologic changes suggested possible axonal damage.