Donor and Recipient Nerve Axon Counts in Gender-affirming Radial Forearm Phalloplasty: Informing Choice of Nerve Coaptations

Abstract

Background:A key component of success of a nerve transfer is the innervation density, which is directly affected by the donor nerve axonal density and donor-torecipient (D:R) axon ratio. Optimal D:R axon ratio for a nerve transfer is quoted at 0.7:1 or greater. In phalloplasty surgery, there are currently minimal data available to help inform selection of donor and recipient nerves, including unavailability of axon counts. Methods: Five transmasculine people who underwent gender-affirming radial forearm phalloplasty had nerve specimens processed with histomorphometric evaluation to determine axon counts and approximate donor-to-recipient axon ratios. Results: Mean axon counts for recipient nerves were 6957 ± 1098 [the lateral antebrachial (LABC)], 1866 ± 590 [medial antebrachial (MABC)], and 1712 ± 121 [posterior antebrachial cutaneous (PABC)]. Mean axon counts for donor nerves were 2301 ± 551 [ilioinguinal (IL)] and 5140 ± 218 [dorsal nerve of the clitoris (DNC)].

Histomorphometry of the Sural Nerve for Use as a CFNG in Facial Reanimation Procedures

“…Axon counts for the lateral and medial antebrachial cutaneous nerve have just been published looking at donor and recipient nerve axon counts in gender-affirming radial forearm phalloplasty. The mean axon counts for the lateral antebrachial cutaneous nerve were 6957 ± 1098, and for the medial antebrachial cutaneous nerve they were 1866 ± 590 [53]. From the sheer axon numbers, those nerves could also be used for autologous nerve grafting [35].…”