Randomized comparison of the single-injection volar subcutaneous block and the two-injection dorsal block for digital anesthesia

BACKGROUND: Two commonly used methods of digital nerve block with local anesthetic are the two-injection dorsal technique and the single-injection volar subcutaneous technique. The authors compared these two digital block techniques with respect to local anesthetic injection pain and recipient preference of anesthetic technique. METHODS: Twenty-seven volunteers had the long finger of each hand injected with 2% lidocaine with 1:100,000 epinephrine. The two-injection dorsal method was used on one long finger and the other long finger received the volar single-injection technique. Volunteers completed a pain scale for each block and were then asked which technique they would prefer. The area of anesthetic skin was assessed in each finger by pinprick testing, and photographs were taken. RESULTS: Although there was a lower pain score for the volar single-injection block, the difference in pain scores between the two techniques was not statistically significant. However, 22 of the 27 subjects indicated that they would select the volar over the dorsal block if a future block was required, and this preference for the volar block was statistically significant. CONCLUSIONS: Although the difference in pain scores between the two techniques was not statistically significant, volunteers who received both blocks would prefer the volar single-injection subcutaneous block if given a choice. Therefore, the single-injection volar subcutaneous block is recommended as the technique of choice for anesthesia of the digit, except in patients for whom anesthesia over the dorsum of the proximal phalanx is required. These patients may prefer a supplementary dorsal nerve block or a traditional two-injection block.