I received trigger point injections into the L scalenes once at the UCLA East-West Medicine Center, and by the time I got to my car, my left arm was completely dead! The young Western doc administering the injections must have inadvertently hit the neurovascular bundle by mistake. This is why the type of imaging technique used is so important. My experience was several years ago; as I recall the doc only palpated the scalenes to locate his target. We TOSers so often have anatomical anomalies in this area, nerves running through muscles where they shouldn't, etc. The "deadness" only lasted a few hours, but it was scary at the time! Good luck with your procedures. I know you'll be careful.