Multimodal Evaluation of Functional Nerve Regeneration in Transgender Individuals After Phalloplasty With a Free Radial Forearm Flap.

[BACKGROUND] Constructing a sensitive phallus is a key objective in sex affirmation surgery, but still there is a major lack of evidence in outcome analysis of postoperative sensibility of the newly constructed body part.

[AIM] To evaluate the innervation and sensibility of a forearm free-flap neophallus with nerve coaptation by a broad-spectrum follow-up.

[METHODS] The phallic sensibility of 20 transgender individuals who underwent phalloplasty with a free radial forearm flap was evaluated by a standardized multimodal approach, examining 5 main sensory modalities. Measurements were performed in defined areas at the phallus and at the unoperated forearm as a control area. Additionally, all patients were asked to complete a questionnaire about their subjective quality of life and ability to orgasm.

[OUTCOME] This study evaluated the following parameters: perception of pressure (Semmes-Weinstein monofilaments) and vibration (C64 Hz tuning fork), static two-point discrimination, sharp-blunt and hot-cold discrimination at the phallus and the forearm, sum score of calculated life satisfaction, and ability to orgasm.

[RESULTS] Most of the patients (n = 14) were able to perceive 2 or more sensory modalities tested at the newly constructed phallus. 2 patients did not develop any sensibility. Interestingly, the median values for vibration perception were similar for the phallus and the unoperated forearm. Pressure sensibility was present at the phallus, but less than at the forearm. Moreover, sharp-blunt sensibility was present in 11 patients. In contrast, clear cold-warm discrimination could not be achieved, although the majority of patients detected the cold stimulus. A two-point discrimination of up to 23 mm could not be detected in either body part. 15 patients experienced orgasms without difficulty after 23 months (n = 20 after 54 months).

[CLINICAL IMPLICATIONS] We observed successful recovery of sensibility at the phalli for the majority of patients, including the preservation of orgasm.

[STRENGTHS & LIMITATIONS] Our institution is one of the few centers regularly performing phalloplasties in transgender patients, especially preferring the technique of Gottlieb and Levine. This study contributes to the few studies that perform sensory testing at the phallus and is unique in its kind in that it uses a multimodal approach. A limitation of this study is the limited number of cases and the limited validity of vibratory testing.

[CONCLUSION] Confirming a promising tactile sensibility after phalloplasty with a neurovascular radial forearm flap, the next step would be to identify whether this reinnervation effectively develops due to nerve coaptation or spontaneous sprouting. Küenzlen L, Nasim S, van Neerven S, et al. Multimodal Evaluation of Functional Nerve Regeneration in Transgender Individuals After Phalloplasty With a Free Radial Forearm Flap. J Sex Med 2020;17:1012-1024.