Tactile Hand Sensation Following Split Thickness Radial Forearm Free Flap Phalloplasty

Abstract

PURPOSE: Radial forearm free flap (RFFF) phalloplasty is often referred to as the gold standard for gender-affirming phalloplasty procedures.1 Forearm neuropathy, a frequently listed complication of RFFF phalloplasty, has yet to be quantified in patients who undergo this procedure with a device as precise as the Pressure Specified Sensory Device (PSSD). The purpose of this study was to determine whether there is a change in tactile hand sensation following RFFF phalloplasty, and whether these changes vary by cutaneous region of the hand. The results of this study will help counsel patients who may view potential neuropathy as a barrier to pursuing this procedure. METHODS: A total of 9 patients undergoing split thickness RFFF phalloplasty were tested preoperatively and 1-week postoperatively for tactile hand sensation. Testing was conducted using a 2-point static (2 PS) test with a Disk-Criminator and PSSD. The testing sites included the cutaneous regions of the dorsal first webspace and the first phalanx of the index finger and pollex of the RFFF donor arm. The 2 PSSD prongs were set at a distance determined by initial testing with the Disk-Criminator. The PSSD measured the threshold of pressure necessary for the patient to discriminate 2 points. Two-sided paired t tests compared the pre- and postoperative pressure values on each of the 3 hand locations. The numerical differences in pre- and postoperative pressures were then compared between each of the 3 locations to determine whether or not there was a difference in postoperative sensation based on hand region. The PSSD pressure values were standardized based on the prong distance determined by the Disk-Criminator, and percent change in standardized PSSD score differences for each cutaneous region was calculated. All tests were considered significant at P < 0.05. RESULTS: There were no significant differences between pre- and postoperative PSSD pressures for all cutaneous regions tested (P > 0.05). However, on average, patients required 8.04% more pressure applied in the dorsal first webspace in order to discriminate 2 points, 8.43% more in the first phalanx of the index finger, and 16.7% more in the first phalanx of the pollex postphalloplasty (all n.s.). Furthermore, when comparing each of the three cutaneous regions to each other, there was no difference in the change in pressures between each region (P > 0.05). In other words, each of the three regions of the hand was similarly impacted by the operation. CONCLUSIONS: The results of this study suggest that while past literature reports cases of numbness and/or tingling post-RFFF phalloplasty,1 immediate postoperative sensation is not significantly different than preoperative sensation. The fear of donor arm neuropathy is a potential barrier for patients seeking this life-changing procedure, yet this study quantifies the degree of neuronal damage and may encourage patients to undergo the procedure. These results will help guide patient-physician conversations regarding RFFF phalloplasty in order to create realistic patient expectations for postoperative outcomes. REFERENCE: 1. Kovar A, Choi S, Iorio ML. Donor site morbidity in phalloplasty reconstructions: outcomes of the radial forearm free flap. Plast Reconstr Surg Glob Open. 2019;7:e2442.