“…However, this is the only known case in which it was not clear to what extent the injection of contrast or lidocaine was responsible for this effect. In addition, in the above section, a case was already reported in which fluoroscopy, 2 sequences of DSA, followed by a test block with lidocaine could not prevent the occurrence of tetraplegia . A retrospective study on the use of test blocks in cervical TF injections was able to detect central nervous system symptoms (after real‐time imaging) in 4 of 532 patients (0.75%).…”