In Reply:—
We appreciate the interest in our article1and the comments provided by Dr. Galiano et al. We agree that it may be possible to visualize the third occipital nerve by magnetic resonance imaging too and that ultrasound is therefore not necessarily the only available technique to visualize the third occipital nerve. However, we do not believe that the sources cited by Dr. Galiano et al. support the routine use of magnetic resonance imaging. Ultrasound is a better option for pain physicians because magnetic resonance imaging is much more expensive and still not accessible to most practitioners. The findings of our study are not the result of a subjective interpretation of ultrasound guidance. Because fluoroscopy is the current standard to perform medial branch blocks,2we compared our new method with this technique and injected the same amount of local anesthetic, i.e. , 0.9 ml to block the third occipital nerve as we do during blocks performed under fluoroscopic guidance.3Compared with fluoroscopy, our needle tip was found 82% of the time to be in the predefined target zone, and the findings corresponded with the clinical results of the block. As we stated in the article, our method is an encouraging first step: The new technique should be subject of future studies.
Whether simple cadaver or magnetic resonance imaging studies would provide stronger scientific evidence to support the use of a new method, compared with the combined radiologic and clinical control performed in our study, remains questionable.
*University of Bern, Bern, Switzerland. urs.eichenberger@insel.ch
