To the Editor
The case report by Wendling et al.1 describes the fracture of the tip of a 27-gauge spinal needle inserted through a 17-gauge Tuohy needle during an attempt to perform a spinal anesthetic. The stylet was taken out of the spinal needle, and with it advanced 1 cm beyond the tip of the Tuohy both needles were advanced together. The spinal needle was then pulled out and found to have lost its tip. As a result, Wendling et al.1 recommended limiting the number of needle passes made, withdrawing the 2 needles together as a unit, and not withdrawing the spinal needle through the Tuohy. Although I agree with these recommendations, Wendling et al.1 fail to mention a more important point.
As a part of a similar case report,2 we studied the exact nature of what causes needles to fracture and learned that, when a hollow needle is placed under excessive axial stress, it will bend, and eventually a crease will form somewhere along the shaft. When the needle is then restored, it will likely fracture at the crease point. However, a hollow needle with a stylet in place will not allow the crease to form. In effect, the stylet makes the needle function more like a solid metal shaft, making it more impervious to fracture. Although it is true that epidural needles are generally advanced without the stylet, reports of fractures are relatively unlikely because only larger needles (18 gauge or larger) are used.
In the case reported by Wendling et al.,1 if a stylet had been in place, there would have likely been resistance to pulling it out if the needle was severely bent. This would have been the clue to remove both needles as a unit to avoid breakage. The most important lesson of the report by Wendling et al.1 is to always advance a fine-gauge spinal needle with a stylet in place.
Steven M. Dunn, MD
Department of Anesthesiology
Baystate Medical Center/Tufts University Medical School
Dr. Wendling does not wish to respond.
1. Wendling AL, Wendling MT, Gravenstien D, Euliana TY. Fractured small gauge needle during attempted combined spinal-epidural anesthesia for cesarean delivery. Anesth Analg 2010;111:245
2. Dunn SM, Steinberg RB, O'Sullivan PS, Goolishian WT, Villa EA. A fractured epidural needle: case report and study. Anesth Analg 1992;60:292–8