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Hontscharuk et al. Plast Aesthet Res 2020;7:65 I http://dx.doi.org/10.20517/2347-9264.2020.124 Page 9 of 15

studied in the field of gender affirmation surgery. A suture-only epineurial nerve repair remains the
mainstay of care. An end-to-end repair is usually performed, but end-to-side and epineural sleeve repairs
[60]
have been described . When a tension-free coaptation is not possible, synthetic or biological conduits may
[61]
be used . In the field of peripheral nerve surgery, connector-assisted coaptations may decrease operative
[62]
time, improve sensory outcomes, and decrease pain . Multiple pharmacologic agents, such as Acetyl-
L-carnitine, testosterone, and various growth factors have been investigated as a means to enhance nerve
regeneration [63,64] . New approaches and techniques are under investigation, and the role of molecular, stem
[65]
cell-based or gene therapies in nerve regeneration may play an important role in the future .

The restoration of protective or tactile sensation is important in helping to avoid incidental injuries to the
neophallus, but also in facilitating retention of an erectile prosthesis [24,29,58] . In addition, consistent with
[11]
reports of penile reconstruction in cisgender men , restoration of tactile sensation contributes to the
[29]
orgasm experience in transgender men . To achieve tactile or protective sensation, the recipient flap
sensory nerve is typically coapted to the donor ilioinguinal nerve [15,22,24,25,28-30] .

There is no consistent method of reporting or assessing tactile sensation following phalloplasty procedures.
[28]
In general, tactile sensation returns ~ 1 year following surgery [15,22] , however, Fang et al. reported sensory
[29]
recovery approximately 6 months following surgery. Selvaggi et al. reported pressure thresholds over
the glans and corona of the neophallus (RFF) comparable to penile controls. Vibratory thresholds were
consistent with the restoration of tactile sensitivity. However, these thresholds were high in comparison to
[22]
penile controls, indicating that sensation was low following this procedure. Kim et al. reported outcomes
of 40 transgender men undergoing phalloplasty with a radial forearm osteocutaneous flap. In their series,
the medial antebrachial cutaneous nerve was coapted to the ilioinguinal nerve, and the lateral antebrachial
cutaneous nerve was coapted to the deep pudendal or dorsal clitoral nerve. Sensation was assessed using
the Zachary and Holmes scheme (ranging from S0 to S4). At a 12-month follow-up, all patients recovered
tactile sensation greater than S2. This indicated a minimum recovery of pain and some touch sensibility.
[24]
Monstrey et al. used identical techniques in their cohort of 287 - of mostly transgender male-patients.
After a year, all patients had regained tactile sensitivity.

A common strategy designed to provide erogenous sensation in phalloplasty procedures involves the
coaptation of a flap sensory nerve to the dorsal pudendal nerve or the dorsal clitoral nerve [15,22,24,29] .
Coaptations using the medial antebrachial cutaneous nerve or the lateral antebrachial cutaneous nerve
[15]
are the two most commonly reported techniques . It is theorized that nerve coaptations to the dorsal
clitoral nerve allow the patient to reach orgasm from direct erogenous stimulation following the clitoral
[29]
nerve pathway . Oftentimes, the ilioinguinal nerve is used as a donor nerve to achieve tactile or protective
sensibility and one branch of the dorsal clitoral nerve is used as a donor nerve to achieve erogenous
sensation [15,24,29] . This technique leaves one dorsal clitoral nerve intact and untouched. The denuded
[15]
glans clitoris is then buried at the base of the neophallus. Morrison et al. postulate that even with two
independent nerve coaptations, the sensation of the reconstructed neophallus differs from that of cisgender
men; however, no direct comparisons have been reported. Some authors advocate using only the dorsal
clitoral nerves for the restoration of both tactile and erogenous sensation [8,10,23,26,31,34,42,66] . This follows the
reconstructive concepts employed in cisgender men undergoing penile reconstruction [11,35,58,67-69] .

Despite few studies using validated measures to assess tactile sensation, reports of sensation, independent
of flap type, are reported in the majority of transgender men (83%-100%) following phalloplasty [8,26,31,34,42,66] .
Rubino et al. reported on the use of an ALT flap in one transgender man. In this case, the lateral
[34]
femoral cutaneous nerve was coapted, end-to-side, to one of the dorsal nerves of the clitoris. Six months
after the procedure, tactile sensation along the shaft of the neophallus was reported. Sensory threshold
measurements for temperature and vibration were all within the normal range, and the patient experienced