A Randomized Trial on the Efficacy of Topical Anesthesia for Pain Reduction during Frame Placement for Gamma Knife Radiosurgery

Abstract

Background/Aims: Frame application for gamma knife radiosurgery (GKR) may be perceived as painful by patients. This study was designed to assess the efficacy of EMLA (2.5% lidocaine/2.5% prilocaine) in pain reduction. Methods: This was a prospective, randomized, and controlled trial approved by our institutional review board. Fifty-four patients undergoing outpatient GKR were divided into EMLA and placebo groups. Prior to frame placement, EMLA/placebo was applied to the patient's forehead. A visual analog scale (VAS) was used to measure pain during 4 intervals: frontal injections, occipital injections, frontal screw insertion, and overall discomfort. This study was designed to observe a difference of 1.0 on the VAS at a power of 95%. Results: VAS for EMLA versus placebo for frontal injections (5.2 ± 2.7 vs. 5.7 ± 2.0, respectively; p < 0.45), back injections, (6.5 ± 2.2 vs. 5.9 ± 2.3, respectively; p < 0.30), frontal pins (4.6 ± 2.7 vs. 4.6 ± 2.2, respectively; p < 0.99), and overall discomfort (p < 0.29) were not significantly different. A comparison between back and frontal injections for EMLA (6.54 vs. 5.19, respectively; p < 0.16) and placebo (5.89 vs. 5.68, respectively; p < 0.69) showed no significant difference between group and location (p < 0.21). Conclusion: Application of EMLA did not significantly reduce pain when used preoperatively for frame fixation. EMLA is no longer used as part of our routine for patients undergoing GKR.