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

Abstract

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.

How Sensitive Is the Neophallus? Postphalloplasty Experienced and Objective Sensitivity in Transmasculine Persons

“…Based on these patient-reported outcomes, we have (previous to this study) ceased to connect the medial antebrachial cutaneous nerve in favor of patient comfort. Possible this may also affect the tactile sensitivity outcomes, nevertheless, our patients seem to experience the same level of tactile sensitivity as reported by Selvaggi et al and Kuenzlen et al 12 , 17 …”

“…Several previous studies showed that sensory recovery of the neophallus after nerve coaptation is possible for various flap techniques, but the overall tactile sensation recovery remains suboptimal in all presented techniques. 6 , 8 , 10 , 12 , 17 , 18…”

“… 8 , 10 , 17 However, Kuenzlen et al reported that the majority of the transmasculine persons showed some degree of sensitivity in the FRFF neophallus and were able to achieve orgasm by stimulating their neophallus. 12 Holzbach et al described the use of a sensate pedicled anterolateral thigh flap (ALT) for phalloplasty, which was reported to yield some degree of sensitivity, with an ongoing reinnervation at follow-up. 18…”

“…Nerve coaptation in FRFF phalloplasty is mostly performed by coaptation of the medial and lateral antebrachial cutaneous nerves, to one of the 2 dorsal clitoral nerves and to the ilio-inguinalis nerve or genito-femoralis nerve. 12 , 17 When using this technique, patients in our center reported to experience an inconveniently sensitive neourethra. Based on these patient-reported outcomes, we have (previous to this study) ceased to connect the medial antebrachial cutaneous nerve in favor of patient comfort.…”

“… 11 Kuenzlen et al performed a short oral survey on erogenous zones and methods to achieve orgasm, but did not compare these results with objectively measured genital sensitivity. 12 …”