Fig. 4. Agreement statistics for needle placement stratified by level (point estimates [blobs ] and 95% CI [whiskers ]). The accuracy of needle placement varied significantly between the different levels both for agreement (A ) (P value for interaction <0.001) and for κ (B ) (P value for interaction = 0.034): it was significantly worse at the medial branch of C7, whereas all other levels showed very good accuracy. TON = third occipital nerve.