In response to Dr. Santiago-Palma’s letter, I agree with most of the points that are made, and certainly the risks of this procedure should be known by anyone who performs them, as well as by their patients. The initial version of my article included a paragraph about the risks of cervical nerve root blocks (CNRBs) that touched on many of the same issues, but it was eventually deleted for diverging from the point of the technical note, which was meant to describe a new way of performing the procedure. Although I agree that there have been a number of cases involving serious complications during CNRBs, a closer review of these cases is necessary before making any assumptions about the safety, or lack thereof, of these procedures.
To begin with, many of the complications have been due to vertebral artery injections or injury, all of which, as far as I can tell, were performed with fluoroscopic guidance. Because CT-fluoroscopy (CTF) enables the radiologist to visualize the vertebral artery both before and throughout the examination, such complications can be avoided with the proper setup and technique. Therefore, although these cases should not be ignored when discussing CTF-guided CNRBs, their importance should be minimized. The second major complication that has been seen is the occurrence of cervical cord infarction, which has occurred in cases using CT, CTF, and fluoroscopic guidance. In these cases, it has been theorized that an injection of particulate steroid material into a dominant radicular artery coursing through the neural foramen is the causative factor, though direct proof of this occurrence is not described in the case reports. Certainly, the injection of contrast before steroid injection is important to ensure there is no vascular filling, and CTF is excellent for looking for such vascular enhancement. I also use a soluble steroid (betamethasone [Celestone], Schering-Plough Corp, Kenilworth, NJ) for all cervical injections and place the needle outside the neural foramen, rather than in it. This precise placement is made possible with the anatomic detail afforded by CTF to guide the needle tip and provide an additional layer of safety. I feel, however, that safety depends not so much on which imaging technique is chosen as on the skill and knowledge of the interventionalist.
It is interesting, however, that in a review of the cases in the literature, as well as medical-legal cases, a significant number of cord infarcts have occurred in cases where there has been contrast injection that demonstrated no vascular enhancement before steroid injection. This puzzling fact suggests that the culprit in at least some of these cases may be spasm of the radicular artery rather than direct injection into the vessel itself. If this is the case, there is really no way to avoid the rare instances when this may happen and in fact the presence of contrast material might act as a causative factor for vasospasm. Fortunately, these types of serious complications are rare when compared with the volume of cases in which these injections have been performed during the past half century. Although it would be interesting to find the exact incidence, the low numbers and the current state of the malpractice environment will likely prevent any meaningful number from being calculated.
In the end, Dr. Santiago-Palma’s objection to my article seems to be my referring to CNRBs as “safe and effective.” I agree that there have been complications and deaths (including at least 2 from unpreventable idiosyncratic drug reactions) that have occurred during these procedures and these risks should be discussed with the patient during the consent process. But ultimately, CNRBs are invasive procedures and as such have a risk of serious complications, including death, just like other invasive or surgical procedures. I stand by my statement that CNRBs are “safe and effective” procedures in well-trained hands. Not 100% safe or 100% effective, but in the world of spine intervention, what is?
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