Fig. 1. Correlation of the radiographic and analgesic spread in 90 patients. (A ) Correlation of right-sided spread of contrast medium with analgesic area. (B ) Correlation of left-sided spread of contrast medium with analgesic area. (C ) Correlation of mean cephalad spread of contrast medium from the catheter tip with analgesic area. (D ) Correlation of mean caudal spread of contrast medium from the catheter tip with analgesic area.