The Effect of a Transdermal Scopolamine Patch on Postoperative Nausea and Vomiting after Retromastoid Craniectomy with Microvascular Decompression: A Preliminary Single Center, Double-Blind, Randomized Controlled Trial

Background: We performed this prospective double-blind randomized controlled trial to identify the effect of a preoperative prophylactic transdermal scopolamine (TDS) patch on postoperative nausea and vomiting (PONV) after retromastoid craniectomy with microvascular decompression (RMC-MVD). Methods: We recruited 38 patients undergoing RMC-MVD and randomized them into two groups: the TDS group (n = 19, application of the TDS patch) and placebo group (n = 19, application of a sham patch). Nausea (as a self-reported 100-mm visual analog scale (VAS) score; range, 0 (no nausea) to 10 (worst nausea)), vomiting, and the use of antiemetics were the primary endpoints. Results: There was no significant difference in terms of the incidence of PONV (73.7% in the TDS group and 78.9% in the placebo group; p = 1.00) between the groups. However, the mean nausea VAS score was significantly different at arrival to the general ward (0.93 +/- 1.71 in the TDS group vs. 2.52 +/- 2.85 in the placebo group; p = 0.046), and throughout the study period (0.03 +/- 0.07 in the TDS group vs. 0.44 +/- 0.71 in the placebo group; p = 0.029). Rescue antiemetics were more frequently used in the placebo group than in the TDS group (9 (47.4%) vs. 2 (10.5%), respectively; p = 0.029). The mean number of antiemetics used throughout the study period was significantly higher in the placebo group than in the TDS group (1.37 +/- 2.19 vs. 0.16 +/- 0.50, respectively; p = 0.029). Conclusions: The preoperative prophylactic use of a TDS patch was safe and effective in the management of PONV after RMC-MVD in terms of the severity of PONV and the use of rescue antiemetics.