To the Editor:—
In the December 2000 issue of Anesthesiology, Benumof 1describes the devastating results of four attempted interscalene nerve blocks (ISB) performed in patients during general anesthesia or heavy sedation. Dr. Benumof concludes that the neurologic injury these patients received was caused by the direct placement of a needle and injection of local anesthetic into the substance of the spinal cord. Three of these cases involved a 22-gauge, 2-in Braun Stimuplex needle, and the fourth case used a 1.5-in, 22-gauge needle that was “walked off” the transverse process of C6 in an attempt to locate the nerve trunks of the brachial plexus. An obvious common characteristic shared by all of these cases was that the patients were rendered incapable, either by general anesthesia or by profound sedation, of responding to the inappropriate placement of a needle and injection of local anesthetic.
While I would like to thank Dr. Benumof for bringing this previously unreported complication of interscalene brachial plexus blockade to our attention, this case report deserves further comment. First, if general anesthesia is not an absolute, but as Dr. Benumof states, a relative contraindication to performing an ISB, under what circumstances would it be appropriate to attempt this procedure in an anesthetized patient? Second, Dr. Benumof recommends that the needle used for an ISB be less than 1.5 in long, but he dissuades the reader from inserting a needle greater than 1.0 or 1.25 in long. I assume he meant that the needle should usually not be inserted more than 1.0–1.25 in into the patient. However, I would like to emphasize that the length of the needle used for an ISB does not necessarily affect the inherent risk or safety of the procedure. If an individual can place a 1.5-in needle into the spinal cord in a patient with a weight of 93 kg and a height of 167 cm (case 3 of Benumof’s report), the same could probably be done with a 1-in needle in a patient with a weight of 55 kg and a height of 167 cm. Likewise, an experienced and knowledgeable practitioner of regional anesthesia can safely place an ISB with a 2-in needle if need be.
Benumof’s case report underscores the importance of a basic principle of regional anesthesia: that its safe and successful practice requires a sound fundamental knowledge of the relevant anatomy, physiology, and pharmacology, as well as the indications and contraindications of the procedure to be undertaken—knowledge gained through medical education, training, and experience. Such knowledge seems to have been lacking in those persons who attempted these nerve blocks with such catastrophic results.