I appreciate the thoughtful comments about my article titled “Nerve Puncture and Apparent Intraneural Injection during Ultrasound-guided Axillary Block Does Not Invariably Result in Neurologic Injury.”1My comments to the individual physicians are listed below.
Drs. Brull, Chan, McCartney, Perlas, and Xu report interesting results from their clinical work and pig studies. My own experience is that needle bevel type does make a great deal of difference in the incidence of neural injury during ultrasound-guided block. The B-bevel needle I commonly use is designed for nerve blocks and has a tip that is similar to the bevel on the Braun needle that Brull et al. use. In contrast, I used an ordinary 22-gauge hypodermic needle for ultrasound-guided blocks in 25 patients. The incidence of nerve injury with motor weakness lasting 3–12 months in this group was 4 out of 25. The incidence of sensory injury lasting up to 3 months was 7 out of 1,324 using a B-bevel needle with ultrasound guidance. There were no motor or long-term sensory injuries in any of the patients in whom a B-bevel needle was used with ultrasound guidance.
Drs. Baciarello, Casati, and Fanelli have misinterpreted my comments. Small injectate volumes do not imply that the perineurium has not been violated. Selander’s study suggests that nerve stimulation may be safer than a paresthesia technique, but is without power to prove it. A commercially available device designed to measure pressures during nerve block would be very useful, especially if it were built into the nerve stimulation device that many practitioners prefer to use. Data to prove that such a device would prevent nerve injuries are not available. Use of devices that are not approved by the US Food and Drug Administration has its own perils.
Dr. Al-Nasser suggests that ultrasound should be used to avoid intraneural injection. This is certainly a safe and prudent practice. My own experience is that injections that surround the nerve but are outside the epineurium do not provide rapid reliable nerve block. At the Lindsay House Surgery Center (Rochester, NY), some individual surgeons perform 20 joint surgeries in a single day. The technique that Dr. Al-Nasser uses is not fast or reliable enough to keep up with this pace in my hands.
Drs. Ganesh and Cucchiaro: All blocks were performed with the tip and shaft of the needle in line with the transducer. In some cases, the needle and or transducer had to be manipulated to ensure visualization of the entire needle.
University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania. firstname.lastname@example.org