This was briefly touched on previously, but I have a question regarding TFESI in fusion patients. The question isn’t regarding efficacy, which is certainly an important issue, but rather getting the needle in the right spot. I’ve done a lot of these, and the contrast usually isn’t perfect, but after checking a few views I’m usually confident it’s epidural. Today, I had a patient with L4-S1 lami/fusion with moderate canal stenosis at L3/4, no significant L4/5 NFS. All left-sided pain, sent for left L4 TFESI. I tried from 2 different starting points and both times failed (second time more inferolateral, though my first attempt was already somewhat inferolateral to the target). I kept hitting what I think was fusion mass, not a screw - couldn’t get medial enough. I couldn’t push through the fusion mass (22g needle). I wasn’t even close.
My question is - is it sometimes literally just impossible to do these in patients with fusions? Any way to determine this prior to attempting the injection other than getting a CT? Certain things to look for on an XR?